Background of the Invention
[0001] The present invention relates to compounds capable of activating nicotinic cholinergic
receptors, for example, as agonists of specific nicotinic receptor subtypes.
[0002] Nicotine has been proposed to have a number of pharmacological effects. See, for
example, Pullan et al.
N.
Engl.
J. Med.
330:811-815 (1994). Certain of those effects may be related to effects upon neurotransmitter
release. See for example, Sjak-shie et al.,
Brain Res. 624:295 (1993), where neuroprotective effects of nicotine are proposed. Release of acetylcholine
and dopamine by neurons upon administration of nicotine has been reported by Rowell
et al.,
J.
Neurochem.
43:1593 (1984); Rapier et al.,
J.
Neurochem.
50:1123 (1988); Sandor et al.,
Brain Res. 567:313 (1991) and Vizi,
Br. J. Pharmacol. 47:765 (1973). Release of norepinephrine by neurons upon administration of nicotine
has been reported by Hall et al.,
Biochem. Pharmacol. 21:1829 (1972). Release of serotonin by neurons upon administration of nicotine has
been reported by Hery et al.,
Arch.
Int.
Pharmacodyn.
Ther.
296:91 (1977). Release of glutamate by neurons upon administration of nicotine has been
reported by Toth et al.,
Neurochem Res. 17:265 (1992). In addition, nicotine reportedly potentiates the pharmacological behavior
of certain pharmaceutical compositions used for the treatment of certain disorders.
See, Sanberg et al.,
Pharmacol.
Biochem.
& Behavior 46:303 (1993); Harsing et al.,
J. Neurochem.
59:48 (1993) and Hughes.
Proceedings from Intl.
Symp.
Nic.
S40 (1994). Furthermore, various other beneficial pharmacological effects of nicotine
have been proposed.
See, Decina et al.,
Biol.
Psychiatry 28:502 (1990); Wagner et al.,
Pharmacopsychiatry 21:301 (1988); Pomerleau et al.,
Addictive Behaviors 9:265 (1984); Onaivi et al.,
Life Sci. 54(3):193 (1994); Tripathi et al.,
JPET 221: 91-96 (1982) and Hamon,
Trends in Pharmacol.
Res. 15:36.
[0003] Various nicotinic compounds have been reported as being useful for treating a wide
variety of conditions and disorders. See, for example, Williams et al.
DN&P 7(4):205-227 (1994), Arneric et al.,
CNS Drug Rev. 1(1):1-26 (1995), Americ et al.,
Exp. Opin.
Invest.
Drugs 5(1):79-100 (1996), Bencherif et al.,
JPET 279:1413 (1996), Lippiello et al.,
JPET 279:1422 (1996), Damaj et al.,
Neuroscience (1997), Holladay et al.,
J.
Med.
Chem 40(28): 4169-4194 (1997), Bannon et al.,
Science 279: 77-80 (1998), PCT WO 94/08992, PCT WO 96/31475, and U.S. Patent Nos. 5,583,140 to
Bencherif et al., 5,597,919 to Dull et al., 5,604,231 to Smith et al. and 5,616,716
to Dull et al. Nicotinic compounds are reported as being particularly useful for treating
a wide variety of Central Nervous System (CNS) disorders.
[0004] CNS disorders are a type of neurological disorder. CNS disorders can be drug induced;
can be attributed to genetic predisposition, infection or trauma; or can be of unknown
etiology. CNS disorders comprise neuropsychiatric disorders, neurological diseases
and mental illnesses; and include neurodegenerative diseases, behavioral disorders,
cognitive disorders and cognitive affective disorders. There are several CNS disorders
whose clinical manifestations have been attributed to CNS dysfunction (i.e., disorders
resulting from inappropriate levels of neurotransmitter release, inappropriate properties
of neurotransmitter receptors, and/or inappropriate interaction between neurotransmitters
and neurotransmitter receptors). Several CNS disorders can be attributed to a cholinergic
deficiency, a dopaminergic deficiency, an adrenergic deficiency and/or a serotonergic
deficiency. CNS disorders of relatively common occurrence include presenile dementia
(early onset Alzheimer's disease). senile dementia (dementia of the Alzheimer's type),
Parkinsonism including Parkinson's disease, Huntington's chorea, tardive dyskinesia,
hyperkinesia, mania, attention deficit disorder, anxiety, dyslexia, schizophrenia
and Tourette's syndrome.
[0005] It would be desirable to provide a useful method for the prevention and treatment
of a condition or disorder by administering a nicotinic compound to a patient susceptible
to or suffering from such a condition or disorder. It would be highly beneficial to
provide individuals suffering from certain disorders (e.g., CNS diseases) with interruption
of the symptoms of those disorders by the administration of a pharmaceutical composition
containing an active ingredient having nicotinic pharmacology and which has a beneficial
effect (e.g., upon the functioning of the CNS), but which does not provide any significant
associated side effects. It would be highly desirable to provide a pharmaceutical
composition incorporating a compound which interacts with nicotinic receptors, such
as those which have the potential to affect the functioning of the CNS, but which
compound when employed in an amount sufficient to affect the functioning of the CNS,
does not significantly affect those receptor subtypes which have the potential to
induce undesirable side effects (e.g., appreciable activity at skeletal muscle and
ganglia sites).
Summary of the Invention
[0006] The present invention relates to aryl substituted olefinic amine compounds. Representative
compounds are (4E)-N-methyl-5-(3-pyridyl)-4-penten-2-amine, (4E)-N-methyl-5-(5-pyrimidinyl)-4-penten-2-amine,
(4E)-N-methyl-5-(5-methoxy-3-pyridyl)-4-penten-2-amine, (4E)-N-methyl-5-(6-amino-5-methyl-3-pyridyl)-4-penten-2-amine,
(2R)-(4E)-N-methyl-5-(3-pyridyl)-4-penten-2-amine, (2R)-(4E)-N-methyl-5-(5-isopropoxy-3-pyridyl)-4-penten-2-amine,
(4E)-N-methyl-5-(5-bromo-3-pyridyl)-4-penten-2-amine, (4E)-N-methyl-5-(5-ethoxy-3-pyridyl)-4-penten-2-amine,
(2S)-(4E)-N-methyl-5-(3-pyridyl)-4-penten-2-amine, (4E)-N-methyl-5-(5-isopropoxy-3-pyridyl)-4-penten-2-amine
and (2S)-(4E)-N-methyl-5-(5-isopropoxy-3-pyridyl)-4-penten-2-amine. The present invention
also relates to methods for synthesizing certain aryl substituted olefinic amine compounds,
such as the compounds of the present invention. Of particular interest are isolated
enamiomeric compounds (i.e., compounds in a substantially pure form, as opposed to
racemic mixtures), and methods for synthesizing such enaniomeric compounds in substantially
pure form.
[0007] The present invention also relates to use of the compounds of the present invention
for the prevention or treatment of a wide variety of conditions or disorders, and
particularly those disorders characterized by dysfunction of nicotinic cholinergic
neurotransmission including disorders involving neuromodulation of neurotransmitter
release, such as dopamine release. The present invention also relates to for the prevention
or treatment of disorders, such as central nervous system (CNS) disorders, which are
characterized by an alteration in normal neurotransmitter release. The present invention
also relates to for the treatment of certain conditions (e.g., a method for alleviating
pain). The use involves administering to a subject an effective amount of a compound
of the present invention.
[0008] The present invention, in another aspect, relates to a pharmaceutical composition
comprising an effective amount of a compound of the present invention. Such a pharmaceutical
composition incorporates a compound which, when employed in effective amounts, has
the capability of interacting with relevant nicotinic receptor sites of a subject,
and hence has the capability of acting as a therapeutic agent in the prevention or
treatment of a wide variety of conditions and disorders, particularly those disorders
characterized by an alteration in normal neurotransmitter release.
[0009] The pharmaceutical compositions of the present invention are useful for the prevention
and treatment of disorders, such as CNS disorders. which are characterized by an alteration
in normal neurotransmitter release. The pharmaceutical compositions provide therapeutic
benefit to individuals suffering from such disorders and exhibiting clinical manifestations
of such disorders in that the compounds within those compositions, when employed in
effective amounts, have the potential to (i) exhibit nicotinic pharmacology and affect
relevant nicotinic receptors sites (e.g., act as a pharmacological agonist to activate
nicotinic receptors), and (ii) elicit neurotransmitter secretion, and hence prevent
and suppress the symptoms associated with those diseases. In addition, the compounds
are expected to have the potential to (i) increase the number of nicotinic cholinergic
receptors of the brain of the patient, (ii) exhibit neuroprotective effects and (iii)
when employed in effective amounts do not cause appreciable adverse side effects (e.g.,
significant increases in blood pressure and heart rate, significant negative effects
upon the gastro-intestinal tract, and significant effects upon skeletal muscle). The
pharmaceutical compositions of the present invention are believed to be safe and effective
with regards to prevention and treatment of a wide variety of conditions and disorders.
[0010] The foregoing and other aspects of the present invention are explained in detail
in the detailed description and examples set forth below.
Detailed Description of the Invention
[0011] The compounds of the present invention include compounds of the formula:

where X is independently selected from the group consisting of N, C-F, C-Cl, C-Br,
C-I, C-R', C-NR'R'', C-CF
3, C-CN, C-NO
2, C-C
2R', C-SH, C-SCH
3, C-N
3, C-SO
2CH
3, C-OR', C-SR, C-C(=O)NR'R', C-NR'C(=O)R', C-C(=O)R', C-C(=O)OR', C(CH
2)
qOR', C-OC(=O)R', COC(=O)NR'R'' and C-NR'C(=O)OR' ;
A, A' and A'' are selected from the group consisting of H, F, Cl, Br, I, R', -NR'R'',
-CF
3, -OH, -CN, -NO
2-C
2R', -SH, -SCH
3, N
3, -SO
2CH
3, -OR', -SR', -C(=O)NR'R'', -NR'C(=O)R', -C(=O)R', -C(=O)OR', -(CH
2)
qOR', -OC(=O) R', -OC(=O)NR'R'' and -NR'C(=O)OR' ;
m is 1 or 2;
n is 1;
E
I, E
II, E
III, E
IV and E
VI individually represent hydrogen;
E
V is methyl;
Z' and Z" individually are hydrogen or lower alkyl (e.g., straight chain or branched
alkyl including C
1 - C
8, preferably C
1 - C
5, such as methyl, ethyl, or isopropyl);
R' and R'' are, individually H or lower alkyl (e.g., C
1 - C
10 alkyl, preferably C
1 - C
5 alkyl, and more preferably methyl, ethyl, isopropyl or isobutyl);
R' and R'' can be straight chain or branched alkyl, or R' and R'' can form a cycloalkyl
functionality (e.g., cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, adamantyl,
and quinuclidinyl).
q is an integer from 1 to 6;
the wavy line in the structure indicates that the compound can have a cis (Z) or
trans (E) form.
[0012] A, A' and A'' usually include hydrogen, halo (e.g., F, Cl, Br, or I), alkyl (e.g.,
lower straight chain or branched C
1-8 alkyl, but preferably methyl or ethyl.
[0013] In addition, it is highly preferred that A is hydrogen, it is preferred that A' is
hydrogen, and normally A" is hydrogen. Generally, both A and A' are hydrogen; sometimes
A and A' are hydrogen, and A" is amino, methyl or ethyl; and often A, A' and A" are
all hydrogen. Depending upon the identity and positioning of each individual E
I, E
II, E
III, E
IV, E
V and E
VI, certain compounds can be optically active. Additionally, compounds of the present
invention can have chiral centers within the alkenyl side chain e.g., the compound
can have an R or S configuration depending on the selection of E
III, E
IV, E
V and E
VI, with the S configuration being preferred. Depending upon E
I, E
II, E
III, E
IV, E
V and E
VI, compounds of the present invention have chiral centers, and the present invention
relates to racemic mixtures of such compounds as well as enamiomeric compounds. Typically,
X is CH, CBr or COR.
[0014] Of particular interest are compounds of the formula:

where m, E
I, E
II, E
III, E
IV, X, Z', Z'', A, A' and A'' are as defined hereinbefore.
[0015] Representative compounds of the present invention are (3E) and (3Z)-N-methyl-4(3-pyridyl)-2-methyl-3-buten-1-amine,
(3E) and (3Z)-N-methyl-4-(3-pyridyl)-3-methyl-3 buten-1-amine, (5E) and (5Z)-N-methyl-6-(3-pyridyl)-5-hexen-3-amine,
(4E) and (4Z)-N-methyl-5-(3-pyridyl)-2-methyl-4-penten-2-amine, (4E)and(4Z)-N-methyl-5(3pyridyl)-3-methyl-4-penten-2amine,
(4E) and (4Z)-N-methyl-5-(3-pyridyl)-4-penten-2-amine, (4E) and (4Z)-N-methyl-5-(3-pyridyl)-1,1,1-trifluoro-4-penten-2-amine,
(4E) and (4Z)-N-methyl-5-(3-pyridyl)-4-methyl-4-penten-1-amine, (4E) and (4Z)-N-methyl-5-(3-pyridyl)-4-methyl-4-penten-2-amine,
(1E) and (1Z)-N-methyl-1-(3-pyridyl)-1-octen-4-amine, (1E) and (1Z)-N-methyl-1-(3-pyridyl)-5-methyl-1-hepten-4-amine,
(5E) and (5Z)-N-methyl-6-(3-pyridyl)-5-methyl-5-hexen-2-amine, (5E) and (5Z)-N-methyl-6-(3-pyridyl)-5-hexen-2-amine,(5E)
and (5Z)-N-methyl-6-(3-pyridyl)-5-methyl-5-methyl-5-hexen-3-amine, (3E) and (3Z)-4-(3-pyridyl)-2-methyl-3-buten-1-amine,
(3E) and (3Z)-4-(3-pyridyl)-3-methyl-3-buten-1-amine, (5E) and (5Z)-6-(3-pyridyl)-5-hexen-3-amine,
(4E) and (4Z)-5-(3-pyridyl)-2-methyl-4-penten-2-amine, (4E) and (4Z)-5-(3-pyridyl)-3-methyl-4-penten-2-amine,
(4E) and (4Z)-5-(3-pyridyl)-4-penten-2-amine, (4E) and (4Z)-5-(3-pyridyl)-1,1,1-trifluoro-4-penten-2-amine,
(4E) and (4Z)-5-(3-pyridyl)-4-methyl-4-penten-1-amine, (4E) and (4Z)-5-(3-pyridyl)-4-methyl-4-penten-2-amine,
(1E) and (1Z)-1-(3-pyridyl)-1-octen-4-amine, (5E) and (5Z)-6-(3-pyridyl)-5-methyl-5-hexen-2-amine,
(5E) and (5Z)-6-(3-pyridyl)-5-hexen-2-amine, and (5E) and (5Z)-6-(3-pyridyl)-5-methyl-5-hexen-3-amine.
See. U.S. Patent No. 5,616,716 to Dull et al.
[0016] The manner in which aryl substituted olefinic amine compounds of the present invention
are synthetically produced can vary. (E)-metanicotine-type compounds can be prepared
using the techniques set forth by Löffler et al.,
Chem. Ber.,
42, pp. 3431-3438 (1909) and Laforge,
J.A.C.S.,
50, p. 2477 (1928) from substituted nicotine-type compounds. Certain 6-substituted metanicotine-type
compounds can be prepared from the corresponding 6-substituted nicotine-type compounds
using the general methods of Acheson et al.,
J. Chem. Soc., Perkin Trans. 1,
2, pp. 579-585 (1980). The requisite precursors for such compounds, 6-substituted nicotine-type
compounds, can be synthesized from 6-substituted nicotinic acid esters using the general
methods disclosed by Rondahl,
Acta Pharm. Suec.,
14, pp 113-118 (1977). Preparation of certain 5-substituted metanicotine-type compounds
can be accomplished from the corresponding 5-substituted nicotine-type compounds using
the general method taught by Acheson et al.,
J. Chem. Soc., Perkin Trans. 1,
2, pp. 579-585 (1980). The 5-halo-substituted nicotine-type compounds (e.g., fluoro-
and bromo-substituted nicotine-type compounds) and the 5-amino nicotine-type compounds
can be prepared using the general procedures disclosed by Rondahl,
Act. Pharm. Suec.,
14, pp. 113-118 (1977). The 5-trifluoromethyl nicotine-type compounds can be prepared
using the techniques and materials set forth in Ashimori et al.,
Chem. Pharm. Bull.,
38(9), pp. 2446-2458 (1990) and Rondahl,
Acta Pharm. Suec.,
14, pp.113-118 (1977).
[0017] Furthermore, preparation of certain metanicotine-type compounds can be accomplished
using a palladium catalyzed coupling reaction of an aromatic halide and a terminal
olefin containing a protected amine substituent, removal of the protective group to
obtain a primary amine, and optional alkylation to provide a secondary or tertiary
amine. In particular, certain metanicotine-type compounds can be prepared by subjecting
a 3-halo-substituted, 5-substituted pyridine compound or a 5-halo-substituted pyrimidine
compound to a palladium catalyzed coupling reaction using an olefin possessing a protected
amine functionality (e.g., such an olefin provided by the reaction of a phthalimide
salt with 3-halo-1-propene, 4-halo-1-butene, 5-halo-1-pentene or 6-halo-1-hexene).
See, Frank et al.,
J. Org. Chem.,
43(15), pp. 2947-2949 (1978) and Malek et al.,
J. Org. Chem.,
47, pp. 5395-5397 (1982). Alternatively, certain metanicotine-type compounds can be
prepared by coupling an N-protected, modified amino acid residue, such as 4-(N-methyl-N-
tert-butyloxycarbonyl)aminobutyric acid methyl ester, with an aryl lithium compound, as
can be derived from a suitable aryl halide and butyl lithium. The resulting N-protected
aryl ketone is then chemically reduced to the corresponding alcohol, converted to
the alkyl halide, and subsequently dehydrohalogenated to introduce the olefin functionality.
Removal of the N-protecting group then affords the desired metanicotine-type compound.
[0018] There are a number of different methods for providing (Z)-metanicotine-type compounds.
In one method, (Z)-metanicotine-type compounds can be synthesized from nicotine-type
compounds as a mixture of E and Z isomers; and the (Z)-metanicotine-type compounds
can then be separated by chromatography using the types of techniques disclosed by
Sprouse et al., Abstracts of Papers. p. 32,
Coresta/
TCRC Joint Conference (1972). In another method, metanicotine-type compounds can be prepared by the controlled
hydrogenation of the corresponding acetylenic compound (e.g., an N-methyl-4-(3-pyridinyl)-3-butyn-1-amine
type compound). For example, certain 5-substituted (Z)-metanicotine-type compounds
and certain 6-substituted (Z)-metanicotine-type compounds can be prepared from 5-substituted-3-pyridinecarboxaldehydes
and 6-substituted-3-pyridinecarboxaldehydes, respectively. Representative synthetic
techniques for (Z)-metanicotine-type compounds are set forth in U.S. Patent No. 5,597,919
to Dull et al.
[0019] There are a number of methods by which the (Z)-olefinic isomers of aryl substituted
olefinic amine compounds can be synthetically produced. In one approach, the (Z)-isomers
of aryl substituted olefinic amine compounds can be prepared by the controlled hydrogenation
of the corresponding alkynyl compounds (e.g., a N-methyl-5-(3-pyridyl)-4-butyn-2-amine-type
compound) using commercially available Lindlar catalyst (Aldrich Chemical Company)
using the methodology set forth in H. Lindlar et al.,
Org. Syn.
46: 89 (1966). The requisite alkynyl compounds can be prepared by the palladium catalyzed
coupling of an aromatic halide, preferably a 3-bromopyridine-type or a 3-iodopyridine-type
compound with an alkynyl side chain compound (e.g., an N-methyl-4-pentyn-2-amine-type
compound). Typically the methodolgy set forth in L. Bleicher et al.,
Synlett. 1115 (1995) is used for the palladium catalyzed coupling of an aryl halide with
a monosubstituted alkyne in the presence of copper(I) iodide and triphenylphosphine
and potassium carbonate as a base. Alkynyl compounds such as N-methyl-4-pentyn-2-amine
can be prepared from commercially available 4-pentyn-2-ol (Aldrich Chemical Company)
by treatment with p-toluenesulfonyl chloride in pyridine, followed by reaction of
the resulting 4-pentyn-2-ol p-toluenesulfonate with excess methylamine either as a
40% aqueous solution or as a 2.0 M solution in tetrahydrofuran. In some instances
it may be necessary to protect the amino functionality of the N-methyl-4-pentyn-2-amine-type
compound by treatment with di-tert-butyl dicarbonate to give the tert-butoxycarbonyl
protected amine-type compound. Such protected amine compounds may undergo the palladium
catalyzed coupling with aryl halides and the subsequent controlled hydrogenation of
the resulting alkynyl compound more easily than the unprotected amine compounds. The
tert-butoxycarbonyl protecting group can be easily removed using a strong acid such
as trifluoroacetic acid to yield the (Z)-olefinic isomers of aryl substituted olefinic
amine compounds.
[0020] The methods by which aryl substituted olefinic amine compounds of the present invention
can be synthetically produced can vary. An olefinic alcohol, such as 4-penten-2-ol,
is condensed with an aromatic halide, such as 3-bromopyridine or 3-iodopyridine. Typically,
the types of procedures set forth in Frank et al.,
J. Org. Chem.,
43, pp. 2947-2949 (1978) and Malek et al.,
J. Org. Chem.,
47, pp. 5395-5397 (1982) involving a palladium-catalyzed coupling of an olefin and an
aromatic halide are used. The olefinic alcohol optionally can be protected as a t-butyldimethylsilyl
ether prior to the coupling. Desilylation then produces the olefinic alcohol. The
alcohol condensation product then is converted to an amine using the type of procedures
set forth in deCosta et al.,
J. Org. Chem.,
35, pp. 4334-4343 (1992). Typically, the alcohol condensation product is converted to
the aryl substituted olefinic amine by activation of the alcohol using methanesulfonyl
chloride or p-toluenesulfonyl chloride, followed by mesylate or tosylate displacement
using ammonia, or a primary or secondary amine. Thus, when the amine is ammonia, an
aryl substituted olefinic primary amine compound is provided; when the amine is a
primary amine such as methylamine or cyclobutylamine, an aryl substituted olefinic
secondary amine compound is provided; and when the amine is a secondary amine such
as dimethylamine or pyrrolidine. an aryl substituted olefinic tertiary amine compound
is provided. Other representative olefinic alcohols include 4-penten-1-ol, 5-hexen-2-ol,
5-hexen-3-ol, 3-methyl-3-buten-1-ol, 2-methyl-3-buten-1-ol, 4-methyl-4-penten-1-ol,
4-methyl-4-penten-2-ol, 1-octen-4-ol, 5-methyl-1-hepten-4-ol, 4-methyl-5-hexen-2-ol,
5-methyl-5-hexen-2-ol, 5-hexen-2-ol and 5-methyl-5-hexen-3-ol. Trifluormethyl-substituted
olefinic alcohols, such as 1,1,1-trifluoro-4-penten-2-ol, can be prepared from 1-ethoxy-2,2,2-trifluoro-ethanol
and allyltrimethylsilane using the procedures of Kubota et al.,
Tetrahedron Letters, Vol. 33(10), pp. 1351-1354 (1992), or from trifluoroacetic acid ethyl ester and
allyltributylstannane using the procedures of Ishihara et al.,
Tetrahedron Letters, Vol. 34(56), pp. 5777-5780 (1993). Certain olefinic alcohols are optically active,
and can be used as enantiomeric mixtures or as pure enantiomers in order to provide
the corresponding optically active forms of aryl substituted olefinic amine compounds.
When an olefinic allylic alcohol, such as methallyl alcohol, is reacted with an aromatic
halide, an aryl substituted olefinic aldehyde is produced; and the resulting aldehyde
can be converted to an aryl substituted olefinic amine compound by reductive amination
(e.g., by treatment using an alkyl amine and sodium cyanoborohydride). Preferred aromatic
halides are 3-bromopyridine-type compounds and 3-iodopyridine-type compounds. Typically,
substituent groups of such 3-halopyridine-type compounds are such that those groups
can survive contact with those chemicals (e.g., tosylchloride and methylamine) and
the reaction conditions experienced during the preparation of the aryl substituted
olefinic amine compound. Alternatively, substituents such as -OH, -NH
2 and -SH can be protected as corresponding acyl compounds, or substituents such as
-NH
2 can be protected as a phthalimide functionality.
[0021] The manner in which certain aryl substituted olefinic amine compounds possessing
a branched side chain, such as (4E)-N-methyl-5-(5-isopropoxy-3-pyridyl)-4-penten-2-amine,
are provided can vary. By using one synthetic approach, the latter compound can be
synthesized in a convergent manner, in which the side chain, N-methyl-N-(tert-butoxycarbonyl)-4-penten-2-amine
is coupled with the 3-substituted 5-halo-substituted pyridine, 5-bromo-3-isopropoxypyridine,
under Heck reaction conditions, followed by removal of the tert-butoxycarbonyl protecting
group. Typically, the types of procedures set forth in W. C. Frank et al.,
J.
Org. Chem.
43: 2947 (1978) and N. J. Malek et al.,
J. Org.
Chem.
47: 5395 (1982) involving a palladium-catalyzed coupling of an olefin and an aromatic
halide are used. The required N-methyl-N-(tert-butoxycarbonyl)-4-penten-2-amine can
be synthesized as follows: (i) Commercially available 4-penten-2-ol (Aldrich Chemical
Company, Lancaster Synthesis Inc.) can be treated with p-toluenesulfonyl chloride
in pyridine to yield 4-penten-2-ol p-toluenesulfonate, previously described by T.
Michel, et al.,
Liebigs Ann.
11: 1811 (1996). (ii) The resulting tosylate can be heated with 20 molar equivalents
of methylamine as a 40% aqueous solution to yield N-methyl-4-penten-2-amine. (iii)
The resulting amine. such as previously mentioned by A. Viola et al.,
J.
Chem. Soc.,
Chem.
Commun.
(21): 1429 (1984), can be allowed to react with 1.2 molar equivalents of di-tert-butyl
dicarbonate in dry tetrahydrofuran to yield the side chain, N-methyl-N-(tert-butoxycarbonyl)-4-penten-2-amine.
The halo-substituted pyridine, (e.g., 5-bromo-3-isopropoxypyridine) can be synthesized
by two different routes. In one preparation, 3,5-dibromopyridine is heated at 140°C
for 14 hours with 2 molar equivalents of potassium isopropoxide in dry isopropanol
in the presence of copper powder (5%, w/w of the 3,5-dibromopyridine) in a sealed
glass tube to yield 5-bromo-3-isopropoxypyridine. A second preparation of 5-bromo-3-isopropoxypyridine
from 5-bromonicotinic acid can be performed as follows: (i) 5-Bromonicotinic acid
is converted to 5-bromonicotinamide by treatment with thionyl chloride, followed by
reaction of the intermediate acid chloride with aqueous ammonia. (ii) The resulting
5-bromonicotinamide, previously described by C. V. Greco et al.,
J.
Hereocyclic Chem.
7(4): 761 (1970), is subjected to Hofmann degradation by treatment with sodium hydroxide
and a 70% solution of calcium hypochlorite. (iii) The resulting 3-amino-5-bromopyridine,
previously described by C. V. Greco et al.,
J. Heteocyclic Chem.
7(4): 761 (1970), can be converted to 5-bromo-3-isopropoxypyridine by diazotization with
isoamyl nitrite under acidic conditions, followed by treatment of the intermediate
diazonium salt with isopropanol to yield 5-bromo-3-isopropoxypyridine. The palladium-catalyzed
coupling of 5-bromo-3-isopropoxypyridine and N-methyl-N-(tert-butoxycarbonyl)-4-penten-2-amine
is carried out in acetonitrile-triethylamine (2:1, v,v) using a catalyst consisting
of 1 mole % palladium(II) acetate and 4 mole % tri-o-tolylphosphine. The reaction
can be carried out by heating the components at 80°C for 20 hours to yield (4E)-N-methyl-N-(tert-butoxycarbonyl)-5-(5-isopropoxy-3-pyridyl)-4-penten-2-amine.
Removal of the tert-butoxycarbonyl protecting group can be accomplished by treatment
with 30 molar equivalents of trifluoroacetic acid in anisole at 0°C to afford (4E)-N-methyl-5-(5-isopropoxy-3-pyridyl)-4-penten-2-amine.
[0022] The manner in which certain aryl substituted olefinic amine compounds possessing
a branched side chain are provided can vary. Using one synthetic approach, a compound
such as (4E)-N-methyl-5-(5-methoxy-3-pyridyl)-4-penten-2-amine can be synthesized
by coupling a halo-substituted pyridine, 5-bromo-3-methoxypyridine with an olefin
containing a secondary alcohol functionality, 4-penten-2-ol, under Heck reaction conditions;
and the resulting pyridyl alcohol intermediate can be converted to its p-toluenesulfonate
ester, followed by treatment with methylamine. Typically, the types of procedures
set forth in W. C. Frank et al.,
J.
Org. Chem.
43: 2947 (1978) and N. J. Malek et al.,
J.
Org. Chem.
47: 5395 (1982) involving a palladium-catalyzed coupling of an olefin and an aromatic
halide are used. The required halo-substituted pyridine, 5-bromo-3-methoxypyridine
is synthesized using methodology similar to that described by H. J. den Hertog et
al.,
Recl.
Trav.
Chim.
Pays-Bas 74:1171 (1955). namely by heating 3,5-dibromopyridine with 2.5 molar equivalents of
sodium methoxide in dry methanol in the presence of copper powder (5%, w/w of the
3,5-dibromopyridine) in a sealed glass tube at 150°C for 14 hours to produce 5-bromo-3-methoxypyridine.
The resulting 5-bromo-3-methoxypyridine, previously described by D. L. Comins, et
al.,
J.
Org.
Chem.
55: 69 (1990), can be coupled with 4-penten-2-ol in acetonitrile-triethylamine (1.1:1.
v/v) using a catalyst consisting of 1 mole % palladium(II) acetate and 4 mole % tri-o-tolylphosphine.
The reaction is carried out by heating the components in a sealed glass tube at 140°C
for 14 hours to yield (4E)-N-methyl-5-(5-methoxy-3-pyridyl)-4-penten-2-ol. The resulting
alcohol is treated with 2 molar equivalents of p-toluenesulfonyl chloride in dry pyridine
at 0°C to produce (4E)-N-methyl-5-(5-methoxy-3-pyridyl)-4-penten-2-ol p-toluensulfonate.
The tosylate intermediate is treated with 120-molar equivalents of methylamine as
a 40% aqueous solution. containing a small amount of ethanol as a co-solvent to produce
(4E)-N-methyl-5-(5-methoxy-3-pyridyl)-4-penten-2-amine.
[0023] The manner in which optically active forms of certain aryl substituted olefinic amine
compounds, such as (2S)-(4E)-N-methyl-5-(3-pyridyl)-4-penten-2-amine, are provided
can vary. In one synthetic approach. the latter type of compound is synthesized by
coupling a halo-substituted pyridine. 3-bromopyridine, with an olefin possessing a
chiral. secondary alcohol functionality, (2R)-4-penten-2-ol, under Heck reaction conditions.
The resulting chiral pyridyl alcohol intermediate, (2R)-(4E)-5-(3-pyridyl)-4-penten-2-ol
is converted to its corresponding p-toluenesulfonate ester. which is subsequently
treated with methylamine, resulting in tosylate displacement with inversion of configuration.
Typically, the types of procedures set forth in W. C. Frank et al.,
J.
Org.
Chem.
43: 2947 (1978) and N. J. Malek et al.,
J.
Org.
Chem.
47: 5395 (1982) involving a palladium-catalyzed coupling of an aromatic halide and an
olefin are used. The chiral side chain (2R)-4-penten-2-ol can be prepared by treatment
of the chiral epoxide. (R)-(+)-propylene oxide (commercially available from Fluka
Chemical Company) with vinylmagnesium bromide in tetrahydrofuran at low temperatures
(-25 to -10°C) using the general synthetic methodology of A. Kalivretenos, J. K. Stille,
and L. S. Hegedus.
J. Org. Chem. 56: 2883 (1991), to afford (2R)-4-penten-2-ol. The resulting chiral alcohol is subjected
to a Heck reaction with 3-bromopyridine in acetonitrile-triethylamine (1:1, v/v) using
a catalyst consisting of 1 mole % palladium(II) acetate and 4 mole % tri-o-tolylphosphine.
The reaction is done by heating the components at 140°C for 14 hours in a sealed glass
tube, to produce the Heck reaction product, (2R)-(4E)-5-(3-pyridyl)-4-penten-2-ol.
The resulting chiral pyridyl alcohol is treated with 3 molar equivalents of p-toluenesulfonyl
chloride in dry pyridine at 0°C, to afford the tosylate intermediate. The p-toluenesulfonate
ester is heated with 82 molar equivalents of methylamine as a 40% aqueous solution,
containing a small amount of ethanol as a co-solvent, to produce (2S)-(4E)-N-methyl-5-(3-pyridyl)-4-penten-2-amine.
In a similar manner, the corresponding aryl substituted olefinic amine enantiomer,
such as (2R)-(4E)-N-methyl-5-(3-pyridyl)-4-penten-2-amine, can be synthesized by the
Heck coupling of 3-bromopyridine and (2S)-4-penten-2-ol. The resulting intermediate,
(2S)-(4E)-5-(3-pyridyl)-4-penten-2-ol, is converted to its p-toluenesulfonate, which
is subjected to methylamine displacement. The chiral alcohol, (2S)-4-penten-2-ol.
is prepared from (S)-(-)-propylene oxide (commercially available from Aldrich Chemical
Company) using a procedure analogous to that described for the preparation of (2R)-4-penten-2-ol
from (R)-(+)-propylene oxide as reported by A. Kalivretenos, J. K. Stille, and L.
S. Hegedus.
J.
Org.
Chem.
56: 2883 (1991).
[0024] The present invention also relates to use of the compounds defined herein before
in the preparation of a medicament for providing prevention of a condition or disorder
to a subject susceptible to such a condition or disorder. and for providing treatment
to a subject suffering therefrom. For example, the use comprises administering to
a patient an amount of a compound effective for providing some degree of prevention
of the progression of a CNS disorder (i.e., provide protective effects), amelioration
of the symptoms of a CNS disorder, and amelioration of the recurrence of a CNS disorder.
The use involves administering an effective amount of a compound selected from the
general formulae which are set forth hereinbefore. The present invention relates to
a pharmaceutical composition incorporating a compound selected from the general formulae
which are set forth hereinbefore. Optically active compounds can be employed as racemic
mixtures or as enantiomers. The compounds can be employed in a free base form or in
a salt form (e.g., as pharmaceutically acceptable salts). Examples of suitable pharmaceutically
acceptable salts include inorganic acid addition salts such as hydrochloride, hydrobromide,
sulfate, phosphate, and nitrate; organic acid addition salts such as acetate, galactarate,
propionate, succinate, lactate, glycolate, malate, tartrate, citrate, maleate, fumarate,
methanesulfonate, p-toluenesulfonate, and ascorbate; salts with acidic amino acid
such as aspartate and glutamate; alkali metal salts such as sodium salt and potassium
salt; alkaline earth metal salts such as magnesium salt and calcium salt; ammonium
salt; organic basic salts such as trimethylamine salt, triethylamine salt, pyridine
salt, picoline salt, dicyclohexylamine salt, and N.N'-dibenzylethylenediamine salt;
and salts with basic amino acid such as lysine salt and arginine salt. The salts may
be in some cases hydrates or ethanol solvates. Representative salts are provided as
described in U.S. Patent Nos. 5,597,919 to Dull et al., 5,616,716 to Dull et al. and
5,663,356 to Ruecroft et al.
[0025] Compounds of the present invention are useful for treating those types of conditions
and disorders for which other types of nicotinic compounds have been proposed as therapeutics.
See, for example, Williams et al.
DN&P 7(4):205-227 (1994), Americ et al.,
CNS Drug Rev.
1(1):1-26 (1995). Americ et al.,
Exp.
Opin.
Invest.
Drugs 5(1):79-100 (1996), Bencherif et al.,
JPET 279:1413 (1996), Lippiello et al.,
JPET 279:1422 (1996), Damaj et al.,
Neuroscience (1997), Holladay et al.,
J.
Med.
Chem 40(28): 4169-4194 (1997), Bannon et al.,
Science 279: 77-80 (1998), PCT WO 94/08992, PCT WO 96/31475, and U.S. Patent Nos. 5,583,140 to
Bencherif et al., 5,597,919 to Dull et al., and 5,604,231 to Smith et al. Compounds
of the present invention can be used as analgesics, to treat ulcerative colitis, and
to treat convulsions such as those that are symptomatic of epilepsy. CNS disorders
which can be treated with the compounds of the present invention include presenile
dementia (early onset Alzheimer's disease), senile dementia (dementia of the Alzheimer's
type). Parkinsonism including Parkinson's disease. Huntington's chorea, tardive dyskinesia.
hyperkinesia, mania, attention deficit disorder, anxiety, dyslexia, schizophrenia
and Tourette's syndrome.
[0026] The pharmaceutical composition also can include various other components as additives
or adjuncts. Exemplary pharmaceutically acceptable components or adjuncts which are
employed in relevant circumstances include antioxidants, free radical scavenging agents,
peptides, growth factors, antibiotics, bacteriostatic agents, immunosuppressives,
anticoagulants, buffering agents, anti-inflammatory agents, antipyretics, time release
binders, anaesthetics, steroids and corticosteroids. Such components can provide additional
therapeutic benefit, act to affect the therapeutic action of the pharmaceutical composition,
or act towards preventing any potential side effects which may be posed as a result
of administration of the pharmaceutical composition. In certain circumstances, a compound
of the present invention can be employed as part of a pharmaceutical composition with
other compounds intended to prevent or treat a particular disorder.
[0027] The manner in which the compounds are administered can vary. The compounds can be
administered by inhalation (e.g., in the form of an aerosol either nasally or using
delivery articles of the type set forth in U.S. Patent No. 4,922,901 to Brooks et
al.); topically (e.g., in lotion form); orally (e.g., in liquid form within a solvent
such as an aqueous or non-aqueous liquid, or within a solid carrier); intravenously
(e.g., within a dextrose or saline solution); as an infusion or injection (e.g., as
a suspension or as an emulsion in a pharmaceutically acceptable liquid or mixture
of liquids); intrathecally; intracerebro ventricularly; or transdermally (e.g., using
a transdermal patch). Although it is possible to administer the compounds in the form
of a bulk active chemical, it is preferred to present each compound in the form of
a pharmaceutical composition or formulation for efficient and effective administration.
Exemplary methods for administering such compounds will be apparent to the skilled
artisan. For example, the compounds can be administered in the form of a tablet, a
hard gelatin capsule or as a time release capsule. As another example, the compounds
can be delivered transdermally using the types of patch technologies available from
Novartis and Alza Corporation. The administration of the pharmaceutical compositions
of the present invention can be intermittent, or at a gradual, continuous, constant
or controlled rate to a warm-blooded animal, (e.g., a mammal such as a mouse, rat.
cat. rabbit, dog, pig, cow. or monkey); but advantageously is preferably administered
to a human being. In addition, the time of day and the number of times per day that
the pharmaceutical formulation is administered can vary. Administration preferably
is such that the active ingredients of the pharmaceutical formulation interact with
receptor sites within the body of the subject that affect the functioning of the CNS.
More specifically, in treating a CNS disorder administration preferably is such so
as to optimize the effect upon those relevant receptor subtypes which have an effect
upon the functioning of the CNS, while minimizing the effects upon muscle-type receptor
subtypes. Other suitable methods for administering the compounds of the present invention
are described in U.S. Patent No. 5,604,231 to Smith et al., the disclosure of which
is incorporated herein by reference in its entirety.
[0028] The appropriate dose of the compound is that amount effective to prevent occurrence
of the symptoms of the disorder or to treat some symptoms of the disorder from which
the patient suffers. By "effective amount", "therapeutic amount" or "effective dose"
is meant that amount sufficient to elicit the desired pharmacological or therapeutic
effects, thus resulting in effective prevention or treatment of the disorder. Thus,
when treating a CNS disorder, an effective amount of compound is an amount sufficient
to pass across the blood-brain barrier of the subject, to bind to relevant receptor
sites in the brain of the subject, and to activate relevant nicotinic receptor subtypes
(e.g., provide neurotransmitter secretion, thus resulting in effective prevention
or treatment of the disorder). Prevention of the disorder is manifested by delaying
the onset of the symptoms of the disorder. Treatment of the disorder is manifested
by a decrease in the symptoms associated with the disorder or an amelioration of the
recurrence of the symptoms of the disorder. Relative to (E)-metanicotine, compounds
of the present invention are less extensively metabolized (i.e., fewer metabolites
are formed, and the rate of elimination from blood is slower) in mammalian systems.
As such. as compared to (E)-metanicotine, compounds of the present invention are capable
of providing higher absolute plasma concentrations, and are capable of being maintained
within a mammalian system for longer periods of time. Thus, compounds of the present
invention are capable of providing comparable therapeutic effects of (E)-metanicotine
at low doses.
[0029] The effective dose can vary, depending upon factors such as the condition of the
patient, the severity of the symptoms of the disorder, and the manner in which the
pharmaceutical composition is administered. For human patients, the effective dose
of typical compounds generally requires administering the compound in an amount sufficient
to activate relevant receptors to effect neurotransmitter (e.g., dopamine) release
but the amount should be insufficient to induce effects on skeletal muscles and ganglia
to any significant degree. The effective dose of compounds will of course differ from
patient to patient but in general includes amounts starting where CNS effects or other
desired therapeutic effects occur, but below the amount where muscular effects are
observed.
[0030] Typically, the effective dose of compounds generally requires administering the compound
in an amount of less than 5 mg/kg of patient weight. Often, the compounds of the present
invention are administered in an amount from 1 mg to less than 100
ug/kg of patient weight, frequently between about 10
ug to less than 100
ug/kg of patient weight, and preferably between about 10
ug to about 50
ug/kg of patient weight. For compounds of the present invention that do not induce
effects on muscle type nicotinic receptors at low concentrations, the effective dose
is less than 5 mg/kg of patient weight; and often such compounds are administered
in an amount from 50
ug to less than 5 mg/kg of patient weight. The foregoing effective doses typically
represent that amount administered as a single dose, or as one or more doses administered
over a 24 hour period.
[0031] For human patients, the effective dose of typical compounds generally requires administering
the compound in an amount of at least about 1, often at least about 10, and frequently
at least about 25
ug/ 24 hr./ patient. For human patients, the effective dose of typical compounds requires
administering the compound which generally does not exceed about 500, often does not
exceed about 400, and frequently does not exceed about 300
ug/ 24 hr./ patient. In addition, administration of the effective dose is such that
the concentration of the compound within the plasma of the patient normally does not
exceed 500 ng/ml, and frequently does not exceed 100 ng/ml.
[0032] The compounds according to the present invention have the ability to pass across
the blood-brain barrier of the patient. As such, such compounds have the ability to
enter the central nervous system of the patient. The log P values of typical compounds,
which are useful in carrying out the present invention are generally greater than
about 0, often are greater than about 0.5, and frequently are greater than about 1.
The log P values of such typical compounds generally are less than about 3.5, often
are less than about 3, and sometimes are less than about 2.5. Log P values provide
a measure of the ability of a compound to pass across a diffusion barrier, such as
a biological membrane. See, Hansch. et al.,
J. Med.
Chem.
11:1 (1968).
[0033] The compounds accocding to the present invention have the ability to bind to, and
in most circumstances, cause activation of nicotinic cholinergic receptors of the
brain of the patient (e.g., such as those receptors that modulate dopamine release).
As such, such compounds have the ability to express nicotinic pharmacology, and in
particular, to act as nicotinic agonists. The receptor binding constants of typical
compounds useful in carrying out the present invention generally exceed about 0.1
nM. often exceed about 1 nM, and frequently exceed about 10 nM. The receptor binding
constants of such typical compounds generally are less than about 1
uM, often are less than about 100 nM, and frequency are less than about 50 nM. Receptor
binding constants provide a measure of the ability of the compound to bind to half
of the relevant receptor sites of certain brain cells of the patient. See, Cheng,
et al.,
Biochem.
Pharmacol.
22:3099 (1973).
[0034] The compounds according to the present invention have the ability to demonstrate
a nicotinic function by effectively eliciting ion flux through, and/or neurotransmitter
secretion from, nerve ending preparations (e.g., thalamic or striatal synaptosomes).
As such. such compounds have the ability to cause relevant neurons to become activated,
and to release or secrete acetylcholine, dopamine, or other neurotransmitters. Generally,
typical compounds useful in carrying out the present invention effectively provide
for relevant receptor activation in amounts of at least about 30 percent, often at
least about 50 percent, and frequently at least about 75 percent, of that maximally
provided by (S)-(-)-nicotine. Generally, typical compounds useful in carrying out
the present invention are more potent than (S)-(-)-nicotine in eliciting relevant
receptor activation. Generally, typical compounds useful in carrying out the present
invention effectively provide for the secretion of dopamine in amounts of at least
about 50 percent, often at least about 75 percent, and frequently at least about 100
percent, of that maximally provided by (S)-(-)-nicotine. Certain compounds of the
present invention can provide secretion of dopamine in an amount which can exceed
that maximally provided by (S)-(-)-nicotine. Generally, typical compounds useful in
carrying out the present invention are less potent than (S)-(-)-nicotine in eliciting
neurotransmitter secretion, such as dopamine secretion.
[0035] The compounds of the present invention, when employed in effective amounts in accordance
with the uses of the present invention. lack the ability to elicit activation of nicotinic
receptors of human muscle to any significant degree. In that regard, the compounds
of the present invention demonstrate poor ability to cause isotopic rubidium ion flux
through nicotinic receptors in cell preparations expressing muscle-type nicotinic
acetylcholine receptors. Thus. such compounds exhibit receptor activation constants
or EC50 values (i.e., which provide a measure of the concentration of compound needed
to activate half of the relevant receptor sites of the skeletal muscle of a patient)
which are extremely high (i.e., greater than about 100
uM). Generally, typical preferred compounds useful in carrying the present invention
activate isotopic rubidium ion flux by less than 10 percent, often by less than 5
percent, of that maximally provided by S(-) nicotine.
[0036] The compounds of the present invention, when employed in effective amounts in accordance
with the uses of the present invention, are selective to certain relevant nicotinic
receptors, but do not cause significant activation of receptors associated with undesirable
side effects. By this is meant that a particular dose of compound resulting in prevention
and/or treatment of a CNS disorder, is essentially ineffective in eliciting activation
of certain ganglionic-type nicotinic receptors. This selectivity of the compounds
of the present invention against those receptors responsible for cardiovascular side
effects is demonstrated by a lack of the ability of those compounds to activate nicotinic
function of adrenal chromaffin tissue. As such, such compounds have poor ability to
cause isotopic rubidium ion flux through nicotinic receptors in cell preparations
derived from the adrenal gland. Generally, typical preferred compounds useful in carrying
out the present invention activate isotopic rubidium ion flux by less than 10 percent,
often by less than 5 percent, of that maximally provided by S(-) nicotine.
[0037] Compounds of the present invention. when employed in effective amounts in accordance
with the uses of the present invention, are effective towards providing some degree
of prevention of the progression of CNS disorders. amelioration of the symptoms of
CNS disorders, and amelioration to some degree of the recurrence of CNS disorders.
However, such effective amounts of those compounds are not sufficient to elicit any
appreciable side effects, as is demonstrated by decreased effects on preparations
believed to reflect effects on the cardiovascular system, or effects to skeletal muscle.
As such. administration of compounds of the present invention provides a therapeutic
window in which treatment of certain CNS disorders is provided, and side effects are
avoided. That is, an effective dose of a compound of the present invention is sufficient
to provide the desired effects upon the CNS, but is insufficient (i.e., is not at
a high enough level) to provide undesirable side effects. Preferably, effective administration
of a compound of the present invention resulting in treatment of CNS disorders occurs
upon administration of less 1/3, frequently less than 1/5, and often less than 1/10,
that amount sufficient to cause any side effects to a significant degree.
[0038] The following examples are provided to illustrate the present invention, and should
not be construed as limiting thereof. In these examples, all parts and percentages
are by weight, unless otherwise noted. Reaction yields are reported in mole percentages.
Several commercially available starting materials are used throughout the following
examples. 3-Bromopyridine, 3,5-dibromopyridine, 5-bromonicotinic acid, 5-bromopyrimidine,
and 4-penten-2-ol were obtained from Aldrich Chemical Company or Lancaster Synthesis
Inc. 2-Amino-5-bromo-3-methylpyridine was purchased from Maybridge Chemical Company
Ltd. (R)-(+)-propylene oxide was obtained from Fluka Chemical Company, and (S)-(-)-propylene
oxide was obtained from Aldrich Chemical Company. Column chromatography was done using
either Merck silica gel 60 (70-230 mesh) or aluminum oxide (activated, neutral, Brockmann
I, standard grade, ∼150 mesh). Pressure reactions were done in a heavy wall glass
pressure tube (185 mL capacity), with Ace-Thread, and plunger valve available from
Ace Glass Inc. Reaction mixtures were typically heated using a high-temperature silicon
oil bath, and temperatures refer to those of the oil bath. The following abbreviations
are used in the following examples: CHCl
3 for chloroform, CH
2Cl
2 for dichloromethane, CH
3OH for methanol, DMF for N,N-dimethylformamide, and EtOAc for ethyl acetate, THF for
tetrahydrofuran, and Et
3N for triethylamine.
EXAMPLE 1
Determination of Log P Value
[0039] Log P values, which have been used to assess the relative abilities of compounds
to pass across the blood-brain barrier (Hansch, et al.,
J.
Med.
Chem.
ii:1 (1968)), were calculated using the Cerius
2 software package Version 3.5 by Molecular Simulations, Inc.
EXAMPLE 2
Determination of Binding to Relevant Receptor Sites
[0040] Binding of the compounds to relevant receptor sites was determined in accordance
with the techniques described in U.S. Patent No. 5,597,919 to Dull et al. Inhibition
constants (Ki values), reported in nM, were calculated from the IC
50 values using the method of Cheng et al.,
Biochem.
Pharmacol. 22:3099 (1973).
EXAMPLE 3
Determination of Dopamine Release
[0041] Dopamine release was measured using the techniques described in U.S. Patent No. 5,597,919
to Dull et al. Release is expressed as a percentage of release obtained with a concentration
of (S)-(-)-nicotine resulting in maximal effects. Reported EC
50 values are expressed in nM, and E
max values represent the amount released relative to (S)-(-)-nicotine on a percentage
basis.
EXAMPLE 4
Determination of Rubidium Ion Release
[0042] Rubidium release was measured using the techniques described in Bencherif et al.,
JPET,
279: 1413-1421 (1996). Reported EC
50 values are expressed in nM, and E
max values represent the amount of rubidium ion released relative to 300
uM tetramethylammonium ion, on a percentage basis.
EXAMPLE 5
Determination of Interaction with Muscle Receptors
[0043] The determination of the interaction of the compounds with muscle receptors was carried
out in accordance with the techniques described in U.S. Patent No. 5,597,919 to Dull
et al. The maximal activation for individual compounds (E
max) was determined as a percentage of the maximal activation induced by (S)-(-)-nicotine.
Reported E
max values represent the amount released relative to (S)-(-)-nicotine on a percentage
basis.
EXAMPLE 6
Determination of Interaction with Ganglion Receptors
[0044] The determination of the interaction of the compounds with ganglionic receptors was
carried out in accordance with the techniques described in U.S. Patent No. 5,597,919
to Dull et al. The maximal activation for individual compounds (E
max) was determined as a percentage of the maximal activation induced by (S)-(-)-nicotine.
Reported E
max values represent the amount released relative to (S)-(-)-nicotine on a percentage
basis.
EXAMPLE 7
[0045] Sample No. 1 is (4E)-N-methyl-5-(3-pyridyl)-4-penten-2-amine hemigalactarate, which
was prepared in accordance with the following techniques:
(4E)-5-(3-Pyridyl)-4-penten-2-ol
[0046] A mixture of 3-bromopyridine (7.50 g, 47.46 mmol), 4-penten-2-ol (4.90 g, 56.96 mmol),
palladium(II) acetate (106 mg, 0.47 mmol), tri-o-tolylphosphine (575 mg, 1.89 mmol),
triethylamine (28.4 mL, 204.11 mmol) and acetonitrile (25 mL) were heated in a sealed
glass tube at 140°C for 14 h. The reaction mixture was cooled to ambient temperature,
diluted with water, and extracted with chloroform (3 x 200 mL). The combined chloroform
extracts were dried over sodium sulfate, filtered, and concentrated by rotary evaporation
to give a pale-yellow oil (7.50 g, 81.0 %).
(4E)-5-(3-Pyridyl)-4-penten-2-ol p-Toluenesulfonate
[0047] To a stirred solution of (4E)-5-(3-pyridyl)-4-penten-2-ol (5.00 g, 30.67 mmol) in
dry pyridine (30 mL) at 0°C was added p-toluenesulfonyl chloride (8.77 g, 46.01 mmol).
The reaction mixture was stirred for 24 h at ambient temperature. The pyridine was
removed by rotary evaporation. Toluene (50 mL) was added to the residue and subsequently
removed by rotary evaporation. The crude product was stirred with a saturated solution
of sodium bicarbonate (100 mL) and extracted with chloroform (3 x 100 mL). The combined
chloroform extracts were dried over sodium sulfate, filtered, and concentrated by
rotary evaporation. The crude product was purified by column chromatography over aluminum
oxide, eluting with ethyl acetate-hexane (3:7, v/v). Selected fractions were combined
and concentrated by rotary evaporation to give a viscous, brown oil (5.83 g, 60.1%).
(4E)-N-Methyl-5-(3-pyridyl)-4-penten-2-amine
[0048] A mixture of (4E)-5-(3-pyridyl)-4-penten-2-ol p-toluenesulfonate (5.60 g, 17.66 mmol),
methylamine (100 mL, 40% solution in water), and ethyl alcohol (10 mL) was stirred
at ambient temperature for 18 h. The resulting solution was extracted with chloroform
(3 x 100 mL). The combined chloroform extracts were dried over sodium sulfate, filtered,
and concentrated by rotary evaporation. The crude product was purified by column chromatography
over aluminum oxide, eluting with ethyl acetate-methanol (7:3, v/v). Selected fractions
were combined and concentrated by rotary evaporation, producing an oil. Further purification
by vacuum distillation furnished 1.60 g (51.6%) of a colorless oil, bp 110-120°C at
0.1 mm Hg.
(4E)-N-Methyl-5-(3-pyridyl)-4-penten-2-amine Hemigalactarate
[0049] (4E)-N-Methyl-5-(3-pyridyl)-4-penten-2-amine (1.60 g, 9.10 mmol) was dissolved in
ethyl alcohol (20 mL), assisted by warming to 60°C. The warm solution was treated
with galactaric acid (955 mg, 4.54 mmol) in one portion, followed by the dropwise
addition of water (0.5 mL). The solution was filtered while hot to remove some insoluble
material. The filtrate was allowed to cool to ambient temperature. The resulting crystals
were filtered. washed with anhydrous diethyl ether, and dried under vacuum at 40°C
to yield 1.20 g (47.0%) of a white, crystalline powder, mp 148-150°C.
[0050] Sample No. 1 exhibits a log P of 1.924, and such a favorable log P value indicates
that the compound has the capability of passing the blood-brain barrier. The sample
exhibits a Ki of 83 nM. The low binding constant indicates that the compound exhibits
good high affinity binding to certain CNS nicotinic receptors.
[0051] Sample No. 1 exhibits an EC
50 value of 6600 nM and an E
max value of 113% for dopamine release. Indicating that the compound induces neurotransmitter
release thereby exhibiting known nicotinic pharmacology. The sample exhibits an EC
50 value of 3100 nM and an E
max value of 35% in the rubidium ion flux assay, indicating that the compound effectively
induces activation of CNS nicotinic receptors.
[0052] Sample No. 1 exhibits an E
max of 13% (at a concentration of 100
uM) at muscle-type receptors indicating that the compound does not induce activation
of muscle-type receptors. The sample exhibits an E
max of 62% (at a concentration of 100
uM) at ganglionic-type receptors. At certain levels the compound shows CNS effects
to a significant degree but show neither undesirable muscle nor ganglion effects to
any significant degree. The compound begins to cause muscle and ganglion effects only
when employed in amounts of several times those required to activate rubidium ion
flux and dopamine release, thus indicating a lack of certain undesirable side effects
in subjects receiving administration of that compound.
EXAMPLE 8
[0053] Sample No. 2 is (2R)-(4E)-N-methyl-5-(3-pyridyl)-4-penten-2-amine hemigalactarate,
which was prepared in accordance with the following techniques:
(2S)-4-Penten-2-ol
[0054] (2S)-4-Penten-2-ol was prepared from (S)-(-)-propylene oxide using a procedure similar
to that described for the preparation of (2R)-4-penten-2-ol from (R)-(+)-propylene
oxide as detailed in A. Kalivretenos. J. K. Stille, and L. S. Hegedus,
J.
Org.
Chem.
56: 2883 (1991). Thus, a 1.0M solution of vinylmagnesium bromide in THF (129 mL, 129.0
mmol) was slowly added to a suspension ofcopper(I) iodide (2.46 g, 12.92 mmol) in
dry THF (40 mL, distilled from sodium and benzophenone) at -25°C. After stirring 5
min, a solution of (S)-(-)-propylene oxide (5.00 g, 86.1 mmol) in dry THF (5 mL) was
added. The mixture was allowed to warm to -10°C and placed in a freezer at 0°C for
12 h. The mixture was stirred for an additional 1 h at 0°C and poured into a mixture
of saturated ammonium chloride solution (100 mL) and ice (100 g). The mixture was
stirred for 4 h and extracted with ether (3 x 100 mL). The combined ether extracts
were dried (K
2CO
3), filtered, and concentrated under reduced pressure by rotary evaporation at 0°C.
The resulting brown oil was vacuum distilled to yield 5.86 g (79.1%) of a colorless
distillate, bp 37-39°C at 9 mm Hg.
(2S)-(4E)-S-(3-Pyridyl)-4-penten-2-ol
[0055] A mixture of 3-bromopyridine (11.22 g, 70.58 mmol), (2S)-4-penten-2-ol (5.00 g, 58.05
mmol), palladium(II) acetate (527 mg, 2.35 mmol), tri-o-tolylphosphine (1.79 g, 5.88
mmol), triethylamine (30 mL, 216 mmol) and acetonitrile (30mL) were heated in a sealed
glass tube at 130-140°C for 8 h. The reaction mixture was cooled to ambient temperature.
The solvent was removed under reduced pressure on a rotary evaporator. Water (20 mL)
was added and the mixture was extracted with chloroform (4 x 50 mL). The combined
chloroform extracts were dried (K
2CO
3), filtered, and concentrated by rotary evaporation, producing a pale-yellow oil (6.00
g). The crude product was purified by column chromatography over silica gel, eluting
with chloroform-acetone (95:5, v/v). Selected fractions were combined and concentrated
by rotary evaporation, affording 3.95 g (41.7%) of a pale-yellow oil.
(2S)-(4E)-5-(3-Pyridyl)-4-penten-2-ol p-Toluenesufonate
[0056] Under a nitrogen atmosphere, p-toluenesufonyl chloride (7.01 g, 36.77 mmol) was added
to a stirring solution of (2S)-(4E)-5-(3-pyridyl)-4-penten-2-ol (3.00 g, 18.38 mmol)
in dry triethylamine (20 mL) at 0°C. After stirring and warming to ambient temperature
over 18 h, the mixture was stirred with cold, saturated NaHCO
3 solution (50 mL) for 1 hour and extracted with chloroform (3 x 50 mL). The combined
chloroform extracts were dried (K
2CO
3), filtered, and concentrated by rotary evaporation to afford a thick. dark-brown
mass (-7 g). The crude product was purified by column chromatography on silica gel,
eluting with chloroform-acetone (98:2, v/v) to afford 4.00 g (68.6%) of a light-brown
syrup.
(2R)-(4E)-N-Methyl-5-(3-pyridyl)-4-penten-2-amine
[0057] A mixture of (2S)-(4E)-5-(3-pyridyl)-4-penten-2-ol p-toluenesulfonate (3.80 g, 11.97
mmol) and methylamine (20 mL, 2.0M solution in THF) was heated at 100-110°C for 8
h in a sealed glass tube. The mixture was cooled to ambient temperature and concentrated
under reduced pressure on a rotary evaporator. The resulting brown syrup was diluted
with saturated NaHCO
3 solution (25 mL) and extracted with chloroform (4 x 25 mL). The combined chloroform
extracts were dried (K
2CO
3), filtered, and concentrated by rotary evaporation to afford a thick, brown syrup
(2.00 g). The crude product was purified by column chromatography on silica gel, eluting
with chloroform-methanol (95:5, v/v). Selected fractions were combined, concentrated
by rotary evaporation affording a 800 mg (37.9%) of a pale-yellow oil.
(2R)-(4E)-N-Methyl-5-(3-pyridyl)-4-penten-2-amine Hemigalactarate
[0058] Galactaric acid (328.0 mg, 1.56 mmol) and (2R)-(4E)-N-methyl-5-(3-pyridyl)-4-penten-2-amine
(600.0 mg, 3.40 mmol) were dissolved in 2-propanol (5 mL) and water (0.2 mL), assisted
by heating and sonication. The hot solution was filtered to remove some insoluble
material. The solvent was removed on a rotary evaporator, and the residue was dried
under high vacuum, producing a cream-colored syrup. The syrup was dissolved in dry
2-propanol (5 mL) and cooled at 4°C. The resulting precipitate was filtered and dried
under high vacuum to yield 700 mg (79.7%) of an off-white, crystalline powder, mp
131-134°C.
[0059] Sample No. 2 exhibits a log P of 1.924, and such a favorable log P value indicates
that the compound has the capability of passing the blood-brain barrier. The sample
exhibits a Ki of 520 nM, indicating that the compound exhibits binding to certain
CNS nicotinic receptors.
[0060] Sample No. 2 exhibits an EC
50 value of 27400 nM and an E
max value of 76% for dopamine release, indicating that the compound induces neurotransmitter
release thereby exhibiting known nicotinic pharmacology. The sample exhibits an EC
50 value of 4390 nM and an E
max value of 32% in the rubidium ion flux assay, indicating that the compound induces
activation of CNS nicotinic receptors.
[0061] Sample No. 2 exhibits an E
max of 0% (at a concentration of 100
uM) at muscle-type receptors, indicating that the compound does not induce activation
of muscle-type receptors. Sample No. I exhibits an E
max of 36% (at a concentration of 100
uM) at ganglionic-type receptors. The compound has the capability to activate human
CNS receptors without activating muscle-type and ganglionic-type nicotinic acetylcholine
receptors to any significant degree. Thus. there is provided a therapeutic window
for utilization in the treatment of CNS disorders. That is, at certain levels the
compound shows CNS effects to a significant degree but does not show undesirable muscle
and ganglion effects to any significant degree.
EXAMPLE 9
[0062] Sample No. 3 (2S)-(4E)-N-methyl-5-(3-pyridyl)-4-penten-2-amine hemigalactarate, which
was prepared in accordance with the following techniques:
(2R)-4-Penten-2-ol
[0063] (2R)-4-Penten-2-ol was prepared in 82.5% yield from (R)-(+)-propylene oxide according
to procedures set forth in A. Kalivretenos, J. K. Stille, and L. S. Hegedus,
J.
Org.
Chem.
56: 2883 (1991).
(2R)-(4E)-5-(3-Pyridyl)-4-penten-2-ol
[0064] A mixture of 3-bromopyridine (9.17 g, 58.04 mmol), (2R)-4-penten-2-ol (6.00 g, 69.65
mmol), palladium(II) acetate (130 mg, 0.58 mmol), tri-o-tolylphosphine (710 mg, 2.32
mmol), triethylamine (34.7 mL, 249.5 mmol), and acetonitrile (35 mL) were heated in
a sealed glass tube at 140°C for 14 h. The reaction mixture was cooled to ambient
temperature, diluted with water, and extracted with chloroform (3 x 200 mL). The combined
chloroform extracts were dried over sodium sulfate, filtered, and concentrated by
rotary evaporation to give 6.17 g (65.2%) of a pale-yellow oil.
(2R)-(4E)-5-(3-Pyridyl)-4-penten-2-ol p-Toluenesulfonate
[0065] To a stirring solution of (2R)-(4E)-5-(3-pyridyl)-4-penten-2-ol (6.00 g, 36.81 mmol)
in dry pyridine (30 mL) at 0°C was added p-toluenesulfonyl chloride (21.05 g, 110.43
mmol). The reaction mixture was stirred for 24 h at ambient temperature. The pyridine
was removed by rotary evaporation. Toluene (50 mL) was added to the residue and subsequently
removed by rotary evaporation. The crude product was stirred with a saturated solution
of sodium bicarbonate (100 mL) and extracted with chloroform (3 x 100 mL). The combined
chloroform extracts were dried over sodium sulfate, filtered, and concentrated by
rotary evaporation to give 11.67 g (84.0%) of a dark-brown, viscous oil.
(2S)-(4E)-N-Methyl-5-(3-pyridyl)-4-penten-2-amine
[0066] A mixture of (2R)-(4E)-5-(3-pyridyl)-4-penten-2-ol p-toluenesulfonate (9.00 g, 28.35
mmol), methylamine (200 mL, 40% solution in water), and ethyl alcohol (10 mL) was
stirred at ambient temperature for 18 h. The resulting solution was extracted with
chloroform (3 x 100 mL). The combined chloroform extracts were dried over sodium sulfate,
filtered, and concentrated by rotary evaporation. The crude product was purified by
column chromatography over aluminum oxide, eluting with ethyl acetate-methanol (7:3,
v/v). Selected fractions were combined and concentrated by rotary evaporation, producing
an oil. Further purification by vacuum distillation furnished 1.20 g (24.0 %) of a
colorless oil. bp 90-100°C at 0.5 mm Hg.
(2S)-(4E)-N-Methyl-5-(3-pyridyl)-4-penten-2-amine Hemigalactarate
[0067] (2S)-(4E)-N-Methyl-5-(3-pyridyl)-4-penten-2-amine (800 mg, 4.54 mmol) was dissolved
in ethyl alcohol (20 mL), assisted by warming to 60°C. The warm solution was treated
with galactaric acid (477 mg, 2.27 mmol) in one portion, followed by the dropwise
addition of water (0.5 mL). The solution was filtered while hot to remove some insoluble
material. The filtrate was allowed to cool to ambient temperature. The resulting crystals
were filtered, washed with anhydrous diethyl ether, and dried under vacuum at 40°C
to yield 830 mg (65.4%) of an off-white, crystalline powder, mp 141-143°C.
[0068] Sample No. 3 exhibits a log P of 1.924, and such a favorable log P value indicates
that the compound has the capability of passing the blood-brain barrier. The sample
exhibits a Ki of 34 nM. The low binding constant indicates that the compound exhibits
good high affinity binding to certain CNS nicotinic receptors.
[0069] Sample No. 3 exhibits an EC
50 value of 2600 nM and an E
max value of 162% for dopamine release, indicating that the compound effectively induces
neurotransmitter release thereby exhibiting known nicotinic pharmacology. The sample
exhibits an EC
50 value of 45 nM and an E
max value of 33% in the rubidium ion flux assay, indicating that the compound effectively
induces activation of CNS nicotinic receptors.
[0070] Sample No. 3 exhibits an E
max of 0% (at a concentration of 100
uM) at muscle-type receptors, indicating that the compound does not induce activation
of muscle-type receptors. The sample exhibits an E
max of 18% (at a concentration of 100
uM) at ganglionic-type receptors. The compound has the capability to activate human
CNS receptors without activating muscle-type and ganglionic-type nicotinic acetylcholine
receptors to any significant degree. Thus, there is provided a therapeutic window
for utilization in the treatment of CNS disorders. That is, at certain levels the
compound shows CNS effects to a significant degree but does not show undesirable muscle
or ganglion effects to any significant degree.
EXAMPLE 10
[0071] Sample No. 4 is (4E)-N-methyl-5-(5-isopropoxy-3-pyridyl)-4-penten-2-amine hemigalactarate,
which was prepared in accordance with the following techniques:
4-Penten-2-ol p-Toluenesulfonate
[0072] Under a nitrogen atmosphere, p-toluenesulfonyl chloride (16.92 g, 88.75 mmol) was
added to a cold (2°C), stirring solution of 4-penten-2-ol (7.28 g, 84.52 mmol) in
pyridine (60 mL). The solution was stirred at 2-5°C for 2 h and allowed to warm to
ambient temperature over several hours. The mixture, containing white solids, was
poured into cold 3M HCl solution (250 mL) and extracted with CHCl
3 (4 x 75 mL). The combined CHCl
3 extracts were washed with 3M HCl solution (4 x 100 mL), saturated NaCl solution (2
x 50 mL), dried (Na
2SO
4), filtered, concentrated on a rotary evaporator, and further dried under high vacuum
to afford 17.38 g (85.6%) of a light-amber oil.
N-Methyl-4-penten-2-amine
[0073] A glass pressure tube was charged with 4-penten-2-ol p-toluenesulfonate (17.30 g,
71.99 mmol) followed by a 40% solution of aqueous methylamine (111.85 g, 1.44 mol).
The tube was sealed, and the mixture was stirred and heated at 122°C for 16 h and
allowed to cool to ambient temperature. After further cooling to 0-5°C, the light-yellow
solution was saturated with solid NaCl and extracted with diethyl ether (6 x 40 mL,
inhibitor-free). The combined light-yellow ether extracts were dried (Na
2SO
4) and filtered. The ether was removed by distillation at atmospheric pressure using
a 6-inch Vigreaux column and a short-path distillation apparatus. The residual light-yellow
oil was distilled at atmospheric pressure collecting 3.72 g (52.1%) of a colorless
oil, bp 75-105°C.
N-Methyl-N-(tert-butoxycarbonyl)-4-penten-2-amine
[0074] Di-tert-butyl dicarbonate (6.84 g, 31.35 mmol) was quickly added in several portions
to a cold (0-5°C), stirring solution of N-methyl-4-penten-2-amine (3.66 g, 25.68 mmol)
in dry THF (25 mL, freshly distilled from sodium and benzophenone). The resulting
light-yellow solution was stirred and allowed to warm to ambient temperature over
several hours. The solution was concentrated on a rotary evaporator. The resulting
oil was vacuum distilled using a short-path distillation apparatus, collecting 5.22
g (88.4%) of an almost colorless oil, bp 85-86°C at 5.5 mm Hg.
[0075] 5-Bromo-3-isopropoxypyridine can be prepared by two different methods (Method A and
Method B) as described below.
5-Bromo-3-isopropoxypyridine (Method A)
[0076] Potassium metal (6.59 g, 168.84 mmol) was dissolved in dry 2-propanol (60.0 mL) under
nitrogen. The resulting potassium isopropoxide was heated with 3,5-dibromopyridine
(20.00 g, 84.42 mmol ) and copper powder (1 g, 5% by weight of 3,5-dibromopyridine)
at 140°C in a sealed glass tube for 14 h. The reaction mixture was cooled to ambient
temperature and extracted with diethyl ether (4 x 200 mL). The combined ether extracts
were dried over sodium sulfate, filtered, and concentrated by rotary evaporation.
The crude product obtained was purified by column chromatography over aluminum oxide,
eluting with ethyl acetate-hexane (1:9, v/v). Selected fractions were combined and
concentrated by rotary evaporation, producing a pale-yellow oil (12.99 g, 71.2%).
5-Bromo-3-isopropoxypyridine (Method B)
5-Bromonicotinamide
[0077] Under a nitrogen atmosphere, 5-bromonicotinic acid (10.10 g, 50.00 mmol) was dissolved
in thionyl chloride (65.24 g, 0.55 mol), and the resulting solution was stirred 45
min at ambient temperature. Excess thionyl chloride was removed by distillation, and
the residue was dried under high vacuum. The resulting solid was ground to a powder
with a mortar and pestle under a nitrogen atmosphere and quickly added to a 28% solution
of aqueous ammonia at 0°C. The mixture was stirred briefly at 0°C and then at ambient
temperature for 3 h. The crude product was filtered, dried, and recrystallized from
toluene-ethanol (1:1, v/v) to give 6.92 g (68.9%) of 5-bromonicotinamide, mp 210-213°C
(lit. mp 219-219.5°C, see C. V. Greco et al.,
J.
Heteocyclic Chem.
7(4): 761 (1970)).
3-Amino-5-bromopyridine
[0078] Sodium hydroxide (2.50 g, 62.50 mmol) was added to a cold (0°C), stirring suspension
of calcium hypochlorite solution (1.53 g, 7.50 mmol of 70% solution) in water (35
mL). The mixture was stirred 15 min at 0°C and filtered. The clarified filtrate was
cooled and stirred in an ice-salt bath while 5-bromonicotinamide (3.03 g, 15.1 mmol)
was added in one portion. The suspension was stirred 2 h at 0°C, warmed to ambient
temperature, and heated on a steam bath for 1 h. After cooling, the mixture was extracted
with CHCl
3 (2 x 50 mL). The combined CHCl
3 extracts were dried (Na
2SO
4), filtered, and concentrated on a rotary evaporator producing 1.42 g of a light-yellow
solid. The aqueous layer was adjusted to pH 8 with 6M HCl solution and extracted with
CHCl
3 (2 x 50 mL). The combined CHCl
3 extracts were dried (Na
2SO
4), filtered, and concentrated on a rotary evaporator, affording 0.98 g of a brown
solid. Based upon TLC analysis (toluene-ethanol (3:1, v/v)), both crude products were
combined to give 2.40 g which was dissolved in ethanol (10 mL) and filtered to remove
a small amount of a light-yellow solid (80 mg, mp 225-227°C). The filtrate was concentrated
on a rotary evaporator, and the residue was dissolved in 2-propanol (6 mL), filtered,
and cooled to 5°C. The resulting precipitate was filtered and dried to give a small
amount of a tan solid (65 mg, mp 63-64°C). The filtrate was concentrated on a rotary
evaporator, and the residue was dissolved in toluene (5 mL), assisted by heating,
and cooled to 5°C. The resulting precipitate was filtered and dried under vacuum to
give 1.80 g of a brown, crystalline solid, mp 65-67°C. By concentrating the filtrate
and cooling, a second crop of 0.27 g of a brown solid, mp 64-66°C (lit. mp 69-69.5°C,
see C. V. Greco et al.,
J.
Heteocyclic Chem.
7(4): 761 (1970)) was obtained, bringing the total yield to 2.07 g (79.3%).
5-Bromo-3-isopropoxypyridine
[0079] A slurry of 5-amino-3-bromopyridine (1.29 g, 7.46 mmol) in 6M HCl solution (5 mL)
was stirred 30 min at ambient temperature. The mixture was concentrated under high
vacuum, and the residue was vacuum dried for 15 h at 50°C, affording a tan solid.
The solid was slurried in 2-propanol (25 mL), and treated with isoamyl nitrite (1.70
g, 15.00 mmol). The mixture was stirred and heated under reflux for 1.5 h. The solution
was concentrated by rotary evaporation, and the residue was partitioned between diethyl
ether and 1M NaOH solution. The aqueous layer was separated and extracted with ether.
The combined ether extracts were dried (Na
2SO
4), filtered, and concentrated by rotary evaporation producing an orange oil (2.03
g). The oil was purified by vacuum distillation, collecting the fraction with bp 105-115°C
at 9 mm Hg. The distilled product was further purified by column chromatography on
silica gel, eluting with 10→20% (v/v) diethyl ether in hexane. Selected fractions,
based upon TLC analysis (R
f 0.40 in hexane-ether, (4:1, v/v)) were combined and concentrated by rotary evaporation
to give 566.0 mg (35.2%) of a clear, colorless oil. (4E)-N-Methyl-N-(tert-butoxycarbonyl)-5-(5-isopropoxy-3-pyridyl)-4-penten-2-amine
[0080] Under a nitrogen atmosphere, a mixture of 5-bromo-3-isopropoxypyridine (847.0 mg,
3.92 mmol), N-methyl-N-(tert-butoxycarbonyl)-4-penten-2-amine (784.7 mg, 3.94 mmol),
palladium(II) acetate (9.0 mg, 0.04 mmol), tri-o-tolylphosphine (50.0 mg, 0.16 mmol),
triethylamine (0.73 g, 7.21 mmol), and anhydrous acetonitrile (2 mL) was stirred and
heated under reflux at 80°C for 20 h. The mixture, containing solids was cooled, diluted
with water (10 mL), and extracted with CHCl
3 (3 x 10 mL). The combined CHCl
3 extracts were dried (Na
2SO
4), filtered, and concentrated by rotary evaporation to give an oily residue (1.56
g). The crude product was purified by column chromatography on silica gel, eluting
with 25→40% (v/v) ethyl acetate in hexane. Selected fractions containing the product
were combined and concentrated to give 1.15 g (87.8%) of a light-amber oil.
(4E)-N-Methyl-5-(5-isopropoxy-3-pyridyl)-4-penten-2-amine
[0081] Under a nitrogen atmosphere, a cold (0-5°C), stirring solution of (4E)-N-methyl-N-(tert-butoxycarbonyl)-5-(5-isopropoxy-3-pyridyl)-4-penten-2-amine
(150.0 mg, 0.45 mmol) in anisole (2.25 mL) was treated with trifluoroacetic acid (1.49
g, 13.79 mmol) in one portion. The resulting solution was stirred for 15 min at 0-5°C.
TLC analysis on silica gel (EtOAc-hexane (3:1, v/v) and CH
3OH-Et
3N (97.5:2.5, v/v)) indicated almost complete reaction. After stirring for an additional
15 min, the solution was concentrated on a rotary evaporator, followed by further
drying under vacuum at 0.5 mm Hg to give 278 mg of a dark-yellow oil. The oil was
cooled (0-5°C), basified with 10% NaOH solution (2 mL) to pH 12, and saturated NaCl
solution (5 mL) was added. The mixture was extracted with CHCl
3 (5 x 3 mL). The combined CHCl
3 extracts were washed with saturated NaCl solution (5 mL), dried (Na
2SO
4), filtered, concentrated by rotary evaporation, followed by further drying at 0.5
mm Hg to give 104.7 mg of a light-yellow, slightly orange oil. The crude product was
purified by column chromatography on silica gel (20 g), eluting with CH
3OH-Et
3N (100:2, v/v). Selected fractions containing the product (R; 0.37) were combined
and concentrated on a rotary evaporator to afford 72.3 mg of a yellow oil. The oil
was dissolved in CHCl
3 (25 mL), and the CHCl
3 solution was dried (Na
2SO
4), filtered, concentrated by rotary evaporation, and vacuum dried to give 69.3 mg
(66.2%) of a yellow oil.
(4E)-N-Methyl-5-(5-isopropoxy-3-pyridyl)-4-penten-2-amine Hemigalactarate
[0082] (4E)-N-Methyl-5-(5-isopropoxy-3-pyridyl)-4-penten-2-amine (69.3 mg, 0.23 mmol) was
dissolved in CH
3OH (1.5 mL), assisted by heating. The warm solution was treated with galactaric acid
(24.3 mg, 0.12 mmol), followed by water (0.3 mL). The resulting solution was warmed
and filtered through glass wool to remove a few insoluble particles, washing the filter
plug with 0.4 mL of a CH
3OH-H
2O (4:1, v/v) solution. The filtrate was diluted with CH
3OH (1.5 mL), and the light-yellow solution was stored at 5°C for 15 h. No precipitate
had formed; therefore, the solution was concentrated on a rotary evaporator. The resulting
solids were triturated with anhydrous diethyl ether (3 x 6 mL). The product was dried
under a stream of nitrogen, dried under high vacuum, followed by further vacuum drying
at 45°C for 15 h to afford 73.0 mg (93.1 %) of an off-white powder, mp 144-146.5°C.
[0083] Sample No. 4 exhibits a log P of 2.957, and such a favorable log P value indicates
that the compound has the capability of passing the blood-brain barrier. The sample
exhibits a Ki of 10 nM. The low binding constant indicates that the compound exhibits
good high affinity binding to certain CNS nicotinic receptors.
[0084] Sample No. 4 exhibits an EC
50 value of 100 nM and an E
max value of 57% for dopamine release, indicating that the compound effectively induces
neurotransmitter release thereby exhibiting known nicotinic pharmacology. The sample
exhibits an EC
50 value of 100 nM and an E
max value of 60% in the rubidium ion flux assay, indicating that the compound effectively
induces activation of CNS nicotinic receptors.
[0085] Sample No. 4 exhibits an E
max of 15% (at a concentration of 100
uM) at muscle-type receptors. indicating that the compound does not significantly induce
activation of muscle-type receptors. The sample exhibits an E
max of 36% (at a concentration of 100
uM) at ganglionic-type receptors. The compound has the capability to activate human
CNS receptors without activating muscle-type and ganglionic-type nicotinic acetylcholine
receptors to any significant degree. Thus. there is provided a therapeutic window
for utilization in the treatment of CNS disorders. That is, at certain levels the
compound shows CNS effects to a significant degree but does not show undesirable muscle
and ganglion effects to any significant degree. The compound begins to cause muscle
effects and ganglion effects only when employed in amounts greater than those required
to activate rubidium ion flux and dopamine release, thus indicating a lack of undesirable
side effects in subjects receiving administration of this compound.
EXAMPLE 11
[0086] Sample No. 5 is (2R)-(4E)-N-methyl-5-(5-isopropoxy-3-pyridyl)-4-penten-2-amine hemigalactarate,
which was prepared in accordance with the following techniques:
(2S)-4-Penten-2-ol
[0087] (2S)-4-Penten-2-ol was prepared from (S)-(-)-propylene oxide using a procedure similar
to that described for the preparation of (2R)-4-penten-2-ol from (R)-(+)-propylene
oxide as detailed in A. Kalivretenos, J. K. Stille, and L. S. Hegedus,
J.
Org.
Chem.
56: 2883 (1991). Thus, a 1.0M solution of vinylmagnesium bromide in THF (129 mL, 129.0
mmol) was slowly added to a suspension of copper(I) iodide (2.46 g, 12.92 mmol) in
dry THF (40 mL, distilled from sodium and benzophenone) at -25°C. After stirring 5
min, a solution of (S)-(-)-propylene oxide (5.00 g, 86.1 mmol) in dry THF (5 mL) was
added. The mixture was allowed to warm to -10°C and placed in a freezer at 0°C for
12 h. The mixture was stirred for an additional 1 h at 0°C and poured into a mixture
of saturated ammonium chloride solution (100 mL) and ice (100 g). The mixture was
stirred for 4 h and extracted with ether (3 x 100 mL). The combined ether extracts
were dried (K
2CO
3), filtered, and concentrated under reduced pressure by rotary evaporation at 0°C.
The resulting brown oil was vacuum distilled to yield 5.86 g (79.1%) of a colorless
distillate, bp 37-39°C at 9 mm Hg.
(2S)-(4E)-5-(5-Isopropoxy-3-pyridyl)-4-penten-2-ol
[0088] A mixture of 5-bromo-3-isopropoxypyridine (12.56 g, 58.13 mmol), (2S)-4-penten-2-ol
(5.00 g, 58.05 mmol), palladium(II) acetate (130 mg, 0.58 mmol), tri-o-tolylphosphine
(706 mg, 2.32 mmol), triethylamine (35 mL, 252 mmol) and acetonitrile (35mL) were
heated in a sealed glass tube at 130-140°C for 8 h. The reaction mixture was cooled
to ambient temperature. The solvent was removed under reduced pressure on a rotary
evaporator. Water (50 mL) was added and the mixture was extracted with chloroform
(3 x 50 mL). The combined chloroform extracts were dried (K
2CO
3), filtered, and concentrated by rotary evaporation. The crude product was purified
by column chromatography over silica gel, eluting with chloroform-acetone (95:5, v/v).
Selected fractions were combined and concentrated by rotary evaporation, producing
7.80 g (60.7%) of a pale-yellow oil.
(2S)-(4E)-5-(5-Isopropoxy-3-pyridyl)-4-penten-2-ol p-Toluenesulfonate
[0089] Under a nitrogen atmosphere, p-toluenesufonyl chloride (11.45 g, 60.06 mmol) was
added to a stirring solution of (2S)-(4E)-5-(5-isopropoxy-3-pyridyl)-4-penten-2-ol
(7.00 g, 31.63 mmol) in dry triethylamine (30 mL) at 0°C. After stirring and warming
to ambient temperature over 18 h, the mixture was concentrated on a rotary evaporator.
The crude product was stirred with saturated NaHCO
3 solution (100 mL) for 1 hour and extracted with chloroform (3 x 50 mL). The combined
chloroform extracts were dried (K
2CO
3), filtered, and concentrated by rotary evaporation to afford 10.00 g (84.2%) as a
dark-brown oil, which was used without further purification.
(2R)-(4E)-N-Methyl-5-(5-isopropoxy-3-pyridyl)-4-penten-2-amine
[0090] A mixture of (2S)-(4E)-5-(5-isopropoxy-3-pyridyl)-4-penten-2-ol p-toluenesulfonate
(10.00 g, 26.63 mmol) and methylamine (50 mL, 2.0M solution in THF) was heated at
100°C for 10 h in a sealed glass tube. The mixture was cooled to ambient temperature
and concentrated under reduced pressure on a rotary evaporator. The crude product
was treated with saturated NaHCO
3 solution (50 mL) and extracted with chloroform (4 x 50 mL). The combined chloroform
extracts were dried (K
2CO
3), filtered, and concentrated by rotary evaporation to afford a dark-brown oil (3.50
g). The crude product was purified by repeated (twice) column chromatography on silica
gel, eluting with chloroform-methanol (95:5, v/v). Selected fractions were combined,
concentrated by rotary evaporation affording a light-brown oil (2.50 g). The oil was
further purified by vacuum distillation using a short-path distillation apparatus,
collecting 2.05 g (32.9%) of a colorless oil, bp 98-100°C at 0.04 mm Hg.
(2R)-(4E)-N-Methyl-5-(5-isopropoxy-3-pyridyl)-4-penten-2-amine Hemigalactarate
[0091] Galactaric acid (314.0 mg, 1.49 mmol) was dissolved in 2-propanol (10 mL) and water
(∼1 mL), assisted by heating and sonicating over a period of 10 min. A solution of
(2R)-(4E)-N-methyl-5-(5-isopropoxy-3-pyridyl)-4-penten-2-amine (700.3 mg, 2.99 mmol)
in 2-propanol (10 mL) was then added, followed by additional sonicating and heating
at 60°C for 10 min. The hot solution was filtered to remove some insoluble material.
The solvent was removed on a rotary evaporator; the resulting light-brown syrup was
dissolved in dry 2-propanol (5 mL) and cooled at 4°C. The resulting precipitate was
filtered and dried under high vacuum to yield 657 mg (64.8%) of an off-white, crystalline
powder, mp 150-153°C.
[0092] Sample No. 5 exhibits a log P of 2.957, and such a favorable log P value indicates
that the compound has the capability of passing the blood-brain barrier. The sample
exhibits a Ki of 62 nM. The low binding constant indicates that the compound exhibits
good high affinity binding to certain CNS nicotinic receptors.
[0093] Sample No. 5 exhibits an EC
50 value of 634 nM and an E
max value of 38% for dopamine release, indicating that the compound effectively induces
neurotransmitter release thereby exhibiting known nicotinic pharmacology. The sample
exhibits an EC
50 value of 88 nM and an E
max value of 14% in the rubidium ion flux assay, indicating that the compound induces
activation of CNS nicotinic receptors.
[0094] Sample No. 5 exhibits an E
max of 0% (at a concentration of 100
uM) at muscle-type receptors, indicating that the compound does not induce activation
of muscle-type receptors. The sample exhibits an E
max of 14% (at a concentration of 100
uM) at ganglionic-type receptors. The compound has the capability to activate human
CNS receptors without activating muscle-type and ganglionic-type nicotinic acetylcholine
receptors to any significant degree. Thus, there is provided a therapeutic window
for utilization in the treatment of CNS disorders. That is, at certain levels the
compound shows CNS effects to a significant degree but does not show undesirable muscle
and ganglia effects to any significant degree.
EXAMPLE 12
[0095] Sample No. 6 is (2S)-(4E)-N-methyl-5-(5-isopropoxy-3-pyridyl)-4-penten-2-amine hemigalactarate,
which was prepared in accordance with the following techniques:
(2R)-4-Penten-2-ol
[0096] (2R)-4-Penten-2-ol was prepared in 82.5% yield from (R)-(+)-propylene oxide according
to procedures set forth in A. Kalivretenos, J. K. Stille, and L. S. Hegedus,
J.
Org. Chem.
56: 2883 (1991).
(2R)-(4E)-5-(5-Isopropoxy-3-pyridyl)-4-penten-2-ol
[0097] A mixture of 5-bromo-3-isopropoxypyridine (10.26 g, 47.50 mmol), (2R)-4-penten-2-ol
(4.91 g, 57.00 mmol), palladium(II) acetate (106 mg, 0.47 mmol), tri-o-tolylphosphine
(578 mg, 1.90 mmol), triethylamine (28.46 mL, 204.25 mmol), and acetonitrile (30 mL)
were heated in a sealed glass tube at 140°C for 14 h. The reaction mixture was cooled
to ambient temperature, diluted with water, and extracted with chloroform (3 x 200
mL). The combined chloroform extracts were dried over sodium sulfate, filtered, and
concentrated by rotary evaporation to give a pale-yellow oil (8.92 g, 85.0%).
(2R)-(4E)-5-(5-Isopropoxy-3-pyridyl)-4-penten-2-ol p-Toluenesulfonate
[0098] To a stirred solution of (2R)-(4E)-5-(5-isopropoxy-3-pyridyl)-4-penten-2-ol (8.50
g, 38.46 mmol) in dry pyridine (30 mL) at 0°C was added p-toluenesulfonyl chloride
(14.67 g, 76.92 mmol). The reaction mixture was stirred for 24 h at ambient temperature.
The pyridine was removed by rotary evaporation. Toluene (50 mL) was added to the residue
and removed by rotary evaporation. The crude product was stirred with a saturated
solution of sodium bicarbonate (100 mL) and extracted with chloroform (3 x 100 mL).
The combined chloroform extracts were dried over sodium sulfate, filtered, and concentrated
by rotary evaporation to yield a dark-brown, viscous oil (11.75 g, 81.5%).
(2S)-(4E)-N-Methyl-5-(5-isopropoxy-3-pyridyl)-4-penten-2-amine
[0099] A mixture of (2R)-(4E)-5-(5-isopropoxy-3-pyridyl)-4-penten-2-ol p-toluenesulfonate
(11.00 g, 29.33 mmol), methylamine (200 mL, 40% solution in water), and ethyl alcohol
(10 mL) was stirred at ambient temperature for 18 h. The resulting solution was extracted
with chloroform (3 x 100 mL). The combined chloroform extracts were dried over sodium
sulfate, filtered, and concentrated by rotary evaporation. The crude product was purified
by column chromatography over aluminum oxide, eluting with ethyl acetate-methanol
(7:3, v/v). Selected fractions were combined and concentrated by rotary evaporation,
producing an oil. Further purification by vacuum distillation furnished 2.10 g (31.0%)
of a colorless oil, bp 90-100°C at 0.5 mm Hg.
(2S)-(4E)-N-Methyl-5-(5-isopropoxy-3-pyridyl)-4-penten-2-amine Hemigalactarate
[0100] (2S)-(4E)-N-Methyl-5-(5-isopropoxy-3-pyridyl)-4-penten-2-amine (2.00 g, 8.55 mmol)
was dissolved in ethyl alcohol (20 mL), assisted by warming to 70°C. The warm solution
was treated with galactaric acid (900 mg, 4.27 mmol) in one portion, followed by the
dropwise addition of water (0.5 mL). The solution was filtered while hot to remove
some insoluble material. The filtrate was allowed to cool to ambient temperature.
The resulting crystals were filtered, washed with anhydrous diethyl ether, and dried
under vacuum at 40°C to yield a white, crystalline powder (750 mg, 26.0%), mp 140-143°C.
[0101] Sample No. 6 exhibits a log P of 2.957, and such a favorable log P value indicates
that the compound has the capability of passing the blood-brain barrier. The sample
exhibits a Ki of 11 nM. The low binding constant indicates that the compound exhibits
good high affinity binding to certain CNS nicotinic receptors.
[0102] Sample No. 6 exhibits an EC
50 value of 106 nM and an E
max value of 85% for dopamine release, indicating that the compound effectively induces
neurotransmitter release thereby exhibiting known nicotinic pharmacology. The sample
exhibits an EC
50 value of 220 nM and an E
max value of 58% in the rubidium ion flux assay, indicating that the compound effectively
induces activation of CNS nicotinic receptors.
[0103] Sample No. 6 exhibits an E
max of 0% (at a concentration of 100
uM) at muscle-type receptors, indicating that the compound does not induce activation
of muscle-type receptors. The sample exhibits an E
max of 0% (at a concentration of 100
uM) at ganglionic-type receptors. The compound has the capability to activate human
CNS receptors without activating muscle-type and ganglionic-type nicotinic acetylcholine
receptors to any significant degree. Thus, there is provided a therapeutic window
for utilization in the treatment of CNS disorders. That is, at certain levels the
compound shows CNS effects to a significant degree but does not show undesirable muscle
or ganglia effects to any significant degree.
EXAMPLE 13
[0104] Sample No. 7 is (4E)-N-methyl-5-(5-bromo-3-pyridyl)-4-penten-2-amine, which was prepared
in accordance with the following techniques:
(4E)-5-(5-Bromo-3-pyridyl)-4-penten-2-ol
[0105] A mixture of 3,5-dibromopyridine (23.60 g, 100.0 mmol), 4-penten-2-ol (10.8 g, 125.0
mmol), palladium(II) acetate (230 mg, 1.02 mmol), tri-o-tolylphosphine (1.20 g, 3.94
mmol), triethylamine (29.7 mL, 213.45 mmol), and acetonitrile (40 mL) were heated
in a sealed glass tube at 140°C for 14 h. The reaction mixture was cooled to ambient
temperature, diluted with water, and extracted with chloroform (3 x 200 mL). The combined
chloroform extracts were dried over sodium sulfate and filtered. Removal of solvent
by rotary evaporation, followed by column chromatography over silica gel eluting with
acetone-chloroform (1:9, v/v) furnished 8.10 g (34.0%) of a pale-yellow oil.
(4E)-N-Methyl-5-(5-bromo-3-pyridyl)-4-penten-2-amine
[0106] To a stirring solution of (4E)-5-(5-bromo-3-pyridyl)-4-penten-2-ol (3.14 g, 13.0
mmol) in dry pyridine (30 mL) at 0°C was added p-toluenesulfonyl chloride (3.71 g,
19.5 mmol). The reaction mixture was stirred for 24 h at ambient temperature. The
pyridine was removed by rotary evaporation. Toluene (50 mL) was added to the residue
and subsequently removed by rotary evaporation. The crude product was stirred with
a saturated solution of sodium bicarbonate (100 mL) and extracted with chloroform
(3 x 100 mL). The combined chloroform extracts were dried over sodium sulfate, filtered,
and concentrated by rotary evaporation to give (4E)-5-(5-bromo-3-pyridyl)-4-penten-2-ol
p-toluenesulfonate. The resulting tosylate was treated with excess methylamine (40%
solution in water), ethyl alcohol (10 mL), and stirred at ambient temperature for
18 h. The resulting solution was extracted with chloroform (3 x 100 mL). The combined
chloroform extracts were dried over sodium sulfate and filtered. Removal of solvent
by rotary evaporation followed by column chromatography over silica gel eluting with
chloroform-methanol (95:5, v/v) produced 1.50 g (45.0%) of a pale-yellow oil.
[0107] Sample No. 7 exhibits a log P of 2.026, and such a favorable log P value indicates
that the compound has the capability of passing the blood-brain barrier. The sample
exhibits a Ki of 284 nM, indicating that the compound exhibits binding to certain
CNS nicotinic receptors.
[0108] Sample No. 7 exhibits an EC
50 value of 202 nM and an E
max value of 18% for dopamine release, indicating that the compound induces neurotransmitter
release thereby exhibiting known nicotinic pharmacology. The sample exhibits an E
max value of 0% in the rubidium ion flux assay, indicating that the compound exhibits
selective effects at certain CNS nicotinic receptors.
[0109] Sample No. 7 exhibits an E
max of 6% (at a concentration of 100
uM) at muscle-type receptors, indicating that the compound does not induce activation
of muscle-type receptors. The sample exhibits an E
max of 8% (at a concentration of 100
uM) at ganglionic-type receptors. The compound has the capability to activate human
CNS receptors without activating muscle-type and ganglionic-type nicotinic acetylcholine
receptors to any significant degree. Thus, there is provided a therapeutic window
for utilization in the treatment of CNS disorders. That is, at certain levels the
compound shows CNS effects to a significant degree but does not show undesirable muscle
or ganglia effects to any significant degree.
EXAMPLE 14
[0110] Sample No. 8 is (4E)-N-methyl-5-(5-methoxy-3-pyridyl)-4-penten-2-amine hemigalactarate,
which was prepared in accordance with the following techniques:
5-Bromo-3-methoxypyridine
[0111] A mixture of 3,5-dibromopyridine (20.00 g, 84.42 mmol), sodium methoxide (11.40 g,
211.06 mmol), and copper powder (1 g, 5% by weight of 3,5-dibromopyridine) in dry
methanol was heated in a sealed glass tube at 150°C for 14 h. The reaction mixture
was cooled to ambient temperature and extracted with diethyl ether (4 x 200 mL). The
combined ether extracts were dried over sodium sulfate, filtered, and concentrated
by rotary evaporation. The crude product was purified by column chromatography over
aluminum oxide, eluting with ethyl acetate-hexane (1:9, v/v). Selected fractions were
combined and concentrated by rotary evaporation, producing 9.40 g (59.5%) of a colorless
oil, which tended to crystallize upon cooling.
(4E)-5-(5-Methoxy-3-pyridyl)-4-penten-2-ol
[0112] A mixture of 5-bromo-3-methoxypyridine (4.11 g, 21.86 mmol), 4-penten-2-ol (2.25
g, 26.23 mmol), palladium(II) acetate (49 mg, 0.22 mmol), tri-o-tolylphosphine (266
mg, 0.87 mmol), triethylamine (13.71 mL, 98.37 mmol), and acetonitrile (15 mL) were
heated in a sealed glass tube at 140°C for 14 h. The reaction mixture was cooled to
ambient temperature, diluted with water, and extracted with chloroform (3 x 200 mL).
The combined chloroform extracts were dried over sodium sulfate. filtered, and concentrated
by rotary evaporation to give 3.53 g (70.3%) of a pale-yellow oil.
(4E)-5-(5-Methoxy-3-pyridyl)-4-penten-2-ol p-Toluenesulfonate
[0113] To a stirred solution of (4E)-5-(5-methoxy-3-pyridyl)-4-penten-2-ol (3.50 g, 18.13
mmol) in dry pyridine (15 mL) at 0°C was added p-toluenesulfonyl chloride (6.91 g,
36.27 mmol). The reaction mixture was stirred for 24 h at ambient temperature. The
pyridine was removed by rotary evaporation. Toluene (50 mL) was added to the residue
and subsequently removed by rotary evaporation. The crude product was stirred with
a saturated solution of sodium bicarbonate (100 mL) and extracted with chloroform
(3 x 100 mL). The combined chloroform extracts were dried over sodium sulfate, filtered,
and concentrated by rotary evaporation to give 5.25 g (83.5%) of a dark-brown, viscous
oil.
(4E)-N-Methyl-5-(5-methoxy-3-pyridyl)-4-penten-2-amine
[0114] A mixture of (4E)-5-(5-methoxy-3-pyridyl)-4-penten-2-ol p-toluenesulfonate (5.00
g, 14.41 mmol), methylamine (150 mL, 40% solution in water), and ethyl alcohol (10
mL) was stirred at ambient temperature for 18 h. The resulting solution was extracted
with chloroform (3 x 100 mL). The combined chloroform extracts were dried over sodium
sulfate, filtered, and concentrated by rotary evaporation. The crude product was purified
by column chromatography over aluminum oxide, eluting with ethyl acetate-methanol
(7:3, v/v). Selected fractions were combined and concentrated by rotary evaporation,
producing an oil. Further purification by vacuum distillation furnished 1.25 g (41.8%)
of a colorless oil, bp 90-100°C at 0.5 mm Hg.
(4E)-N-Methyl-5-(5-methoxy-3-pyridyl)-4-penten-2-amine Hemigalactarate
[0115] (4E)-N-Methyl-5-(5-methoxy-3-pyridyl)-4-penten-2-amine (1.20 g, 5.83 mmol) was dissolved
in ethyl alcohol (20 mL), assisted by warming to 60°C. The warm solution was treated
with galactaric acid (610 mg, 2.91 mmol) in one portion, followed by dropwise addition
of water (0.5 mL). The solution was filtered while hot to remove some insoluble material.
The filtrate was allowed to cool to ambient temperature. The resulting crystals were
filtered, washed with anhydrous diethyl ether, and dried under vacuum at 40°C to yield
1.05 g (58.0%) of a white, crystalline powder, mp 143-145°C.
[0116] Sample No. 8 exhibits a log P of 2.025, and such a favorable log P value indicates
that the compound has the capability of passing the blood-brain barrier. The sample
exhibits a Ki of 22 nM. The low binding constant indicates that the compound exhibits
good high affinity binding to certain CNS nicotinic receptors.
[0117] Sample No. 8 exhibits an EC
50 value of 5000 nM and an E
max value of 110% for dopamine release, indicating that the compound effectively induces
neurotransmitter release thereby exhibiting known nicotinic pharmacology.
[0118] Sample No. 8 exhibits an E
max of 10% (at a concentration of 100
uM) at muscle-type receptors. indicating that the compound does not induce activation
of muscle-type receptors. The sample exhibits an E
max of 2% (at a concentration of 100
uM) at ganglionic-type receptors. The compound has the capability to activate human
CNS receptors without activating muscle-type and ganglionic-type nicotinic acetylcholine
receptors to any significant degree. Thus, there is provided a therapeutic window
for utilization in the treatment of CNS disorders. That is, at certain levels the
compound shows CNS effects to a significant degree but do not show undesirable muscle
or ganglion effects to any significant degree.
EXAMPLE 15
[0119] Sample No. 9 is (4E)-N-methyl-5-(5-ethoxy-3-pyridyl)-4-penten-2-amine hemigalactarate,
which was prepared in accordance with the following techniques:
5-Bromo-3-ethoxypyridine
[0120] Under a nitrogen atmosphere, sodium (4.60 g, 200.0 mmol) was added to absolute ethanol
(100 mL) at 0-5°C, and the stirring mixture was allowed to warm to ambient temperature
over 18 h. To the resulting solution was added 3,5-dibromopyridine (31.50 g, 133.0
mmol), followed by DMF (100 mL). The mixture was heated at 70°C for 48 h. The brown
mixture was cooled, poured into water (600 mL), and extracted with ether (3 x 500
mL). The combined ether extracts were dried (Na
2SO
4), filtered, and concentrated by rotary evaporation, producing 46.70 g of an oil.
Purification by vacuum distillation afforded 22.85 g (85.0%) of an oil, bp 89-90°C
at 2.8 mm Hg, (lit. bp 111°C at 5 mm Hg, see K. Clarke et al.,
J.
Chem.
Soc. 1885 (1960)).
(4E)-N-Methyl-N-(tert-butoxycarbonyl)-5-(5-ethoxy-3-pyridyl)-4-penten-2-amine
[0121] Under a nitrogen atmosphere, a mixture of 5-bromo-3-ethoxypyridine (1.20 g, 5.94
mmol), N-methyl-N-(tert-butoxycarbonyl)-4-penten-2-amine (1.18 g, 5.94 mmol). palladium(II)
acetate (13.5 mg, 0.06 mmol), tri-o-tolylphosphine (73.1 mg, 0.24 mmol), triethylamine
(1.5 mL, 10.8 mmol), and anhydrous acetonitrile (3 mL) was stirred and heated under
reflux at 80-85°C for 28 h. The resulting mixture, containing beige solids, was cooled
to ambient temperature. diluted with water (20 mL), and extracted with CHCl
3 (3 x 20 mL). The combined light-yellow CHCl
3 extracts were dried (Na
2SO
4), filtered, concentrated by rotary evaporation, and vacuum dried producing a yellow
oil (1.69 g). The crude product was purified by column chromatography on silica gel
(100 g), eluting with ethyl acetate-hexane (1:1, v/v). Selected fractions containing
the product (R
f 0.20) were combined, concentrated by rotary evaporation, and the residue was vacuum
dried to give 0.67 g (35.2%) of a light-yellow oil.
(4E)-N-Methyl-5-(5-ethoxy-3-pyridyl)-4-penten-2-amine
[0122] Under a nitrogen atmosphere, a cold (0-5°C), stirring solution of (4E)-N-methyl-N-(tert-butoxycarbonyl)-5-(5-ethoxy-3-pyridyl)-4-penten-2-amine
(0.67 g, 2.09 mmol) in anisole (10 mL) was treated dropwise over 30 min with trifluoroacetic
acid (10.40 g, 91.17 mmol). The resulting solution was stirred for 45 min at 0-5°C
and was then concentrated by rotary evaporation. The light-yellow oil was further
dried under high vacuum at 0.5 mm Hg. The resulting oil was cooled (0-5°C), basified
with 10% NaOH solution (10 mL), treated with saturated NaCl solution (7.5 mL), and
extracted with CHCl
3 (4 x 10 mL). The combined light-yellow CHCl
3 extracts were washed with saturated NaCl solution (20 mL), dried (Na
2SO
4), filtered, concentrated by rotary evaporation, followed by further drying at 0.5
mm Hg producing a brown oil (0.46 g). The crude product was purified by column chromatography
on silica gel (56 g), eluting with CH
3OH-Et
3N (98:2, v/v). Selected fractions containing the product (R
f 0.35) were combined and concentrated on a rotary evaporator. The residue was dissolved
in CHCl
3, and the CHCl
3 solution was dried (Na
2SO
4), filtered. concentrated by rotary evaporation, and vacuum dried to give 327.5 mg
(71.0%) of a light-yellow oil.
(4E)-N-Methyl-5-(5-ethoxy-3-pyridyl)-4-penten-2-amine Hemigalactarate
[0123] To a solution of (4E)-N-methyl-5-(5-ethoxy-3-pyridyl)-4-penten-2-amine (151.4 mg,
0.68 mmol) in absolute ethanol (2.3 mL) was added galactaric acid (72.2 mg, 0.34 mmol).
Water (0.5 mL) was added dropwise while gently warming the light-brown solution. The
solution was filtered through glass wool to remove a few insoluble particles, washing
the filter plug with ethanol-water (4:1, v/v) (1 mL). The filtrate was diluted with
ethanol (3.4 mL), cooled to ambient temperature, and further cooled at 5°C for 18
h. Because no precipitate had formed, the solution was concentrated on a rotary evaporator.
The resulting solids were dried under high vacuum and recrystallized from 2-propanol-water.
After cooling at 5°C for 48 h the product was filtered, washed with cold 2-propanol,
and vacuum dried at 45°C for 6 h. Further vacuum drying at ambient temperature for
18 h afforded 168 mg (76.1%) of a white to off-white powder, mp 141-143.5°C.
[0124] Sample No. 9 exhibits a log P of 2.556, and such a favorable log P value indicates
that the compound has the capability of passing the blood-brain barrier. The sample
exhibits a Ki of 15 nM. The low binding constant indicates that the compound exhibits
good high affinity binding to certain CNS nicotinic receptors.
[0125] Sample No. 9 exhibits an EC
50 value of 520 nM and an E
max value of 85% for dopamine release, indicating that the compound effectively induces
neurotransmitter release thereby exhibiting known nicotinic pharmacology. The sample
exhibits an E
max value of 0% in the rubidium ion flux assay, indicating that the compound exhibits
selective effects at certain CNS nicotinic receptors.
[0126] Sample No. 9 exhibits an E
max of 21 % (at a concentration of 100
uM) at muscle-type receptors, indicating that the compound does not induce activation
of muscle-type receptors. The sample exhibits an E
max of 9% (at a concentration of 100
uM) at ganglionic-type receptors. The compound has the capability to activate human
CNS receptors without activating muscle-type and ganglionic-type nicotinic acetylcholine
receptors to any significant degree. Thus, there is provided a therapeutic window
for utilization in the treatment of CNS disorders. That is, at certain levels the
compound shows CNS effects to a significant degree but does not show undesirable muscle
or ganglia effects to any significant degree.
EXAMPLE 16
[0127] Sample No. 10 is (4E)-N-methyl-5-(6-amino-5-methyl-3-pyridyl)-4-penten-2-amine, which
was prepared in accordance with the following techniques:
(4E)-N-Methyl-N-(tert-butosycarbonyl)-5-(6-amino-5-methyl-3-pyridyl)-4-penten-2-amine
[0128] A mixture of 2-amino-5-bromo-3-methylpyridine (1.41 g, 7.53 mmol), N-methyl-N-(tert-butoxycarbonyl)-4-penten-2-amine
(1.50 g, 7.53 mmol), palladium(II) acetate (33.8 mg, 0.15 mmol), tri-o-tolylphosphine
(183.2 mg, 0.60 mmol), triethylamine (4.50 mL, 32.3 mmol), and anhydrous acetonitrile
(8 mL) was stirred and heated at 130-132°C in a sealed glass tube for 18 h. The mixture
was further heated at 140°C for 84 h. The resulting dark-brown solution was cooled
to ambient temperature and concentrated by rotary evaporation. The residue was diluted
with water (25 mL) and extracted with CH
2Cl
2 (3 x 25 mL). The combined CH
2Cl
2 extracts were dried (Na
2SO
4), filtered, concentrated by rotary evaporation, and vacuum dried producing a dark-brown
oil (2.84 g). The crude product was purified by column chromatography on silica gel
(135 g), eluting with ethyl acetate-hexane (3:1, v/v) to remove impurities, followed
by elution with CH
3OH-Et
3N (98:2, v/v) to collect the product. Fractions containing the product (R
f 0.70) were combined and dissolved in CHCl
3. The CHCl
3 solution was dried (Na
2SO
4), filtered, concentrated by rotary evaporation, and vacuum dried to give 1.11 g (48.4%)
of an amber-brown oil.
(4E)-N-Methyl-5-(6-amino-5-methyl-3-pyridyl)-4-penten-2-amine
[0129] Under a nitrogen atmosphere. trifluoroacetic acid (17.76 g, 155.76 mmol) was added
dropwise, via addition funnel, over 30 min to a cold (0-5°C), stirring solution of
(4E)-N-methyl-N-(tert-butoxycarbonyl)-5-(6-amino-5-methyl-3-pyridyl)-4-penten-2-amine
(1.11 g, 3.47 mmol) in anisole (15 mL). The resulting solution was stirred for 45
min at 0-5°C and was then concentrated by rotary evaporation. The viscous, brown oil
was further dried under high vacuum for 18 h. The crude product was cooled (0-5°C),
basified with 10% NaOH solution (10 mL), treated with saturated NaCl solution (10
mL), and extracted with CHCl
3 (5 x 10 mL). The combined CHCl
3 extracts were dried (Na
2SO
4), filtered, concentrated by rotary evaporation, followed by further drying under
high vacuum yielding a dark-brown oil. The crude product was purified by column chromatography
on silica gel (50 g), eluting with CHCl
3-CH
3OH-Et
3N (4:1:1, v/v/v). Selected fractions containing the product (R
f 0.13) were combined and concentrated by rotary evaporation, and the residue was re-chromatographed
on silica gel (50 g) eluting with CHCl
3-CH
3OH (7:3, v/v). Fractions containing the product (R
f 0.12) were combined and concentrated by rotary evaporation. The residue was dissolved
in CHCl
3, and the CHCl
3 solution was dried (Na
2SO
4), filtered, concentrated by rotary evaporation, and vacuum dried affording a yellow
oil (0.087 g) which tended to crystallize. The semi-crystalline material was dissolved
in a warm solution of hexane containing a small amount of ethyl acetate. The warm
solution was decanted from an insoluble gum. The solution was allowed to cool to ambient
temperature and was further cooled at 5°C for 18 h. The resulting crystalline solids
were collected, washed with hexane, and vacuum dried at 40°C for 16 h. The yield was
30.8 mg (4.3%) of a light-yellow powder, mp 78-81 °C.
[0130] Sample No. 10 exhibits a log P of 1.333, and such a favorable log P value indicates
that the compound has the capability of passing the blood-brain barrier. The sample
exhibits a Ki of 720 nM. The binding constant indicates that the compound exhibits
high affinity binding to certain CNS nicotinic receptors.
[0131] Sample No. 10 exhibits an EC
50 value of 100000 nM and an E
max value of 200% for dopamine release, indicating that the compound induces neurotransmitter
release thereby exhibiting known nicotinic pharmacology.
[0132] Sample No. 10 exhibits an E
max of 0% (at a concentration of 100
uM) at muscle-type receptors, indicating that the compound does not induce activation
of muscle-type receptors. The sample exhibits an E
max of 0% (at a concentration of 100
uM) at ganglionic-type receptors. The compound has the capability to activate human
CNS receptors without activating muscle-type and ganglionic-type nicotinic acetylcholine
receptors to any significant degree. Thus, there is provided a therapeutic window
for utilization in the treatment of CNS disorders.
EXAMPLE 17
[0133] Sample No. 11 is (4E)-N-methyl-5-(5-pyrimidinyl)-4-penten-2-amine hemigalactarate,
which was prepared in accordance with the following techniques:
(4E)-N-Methyl-N-(tert-butoxycarbonyl)-5-(5-pyrimidinyl)-4-penten-2-ol
[0134] A glass pressure tube was charged with a mixture of 5-bromopyrimidine (1.28 g, 8.05
mmol), N-methyl-N-(tert-butoxycarbonyl)-4-penten-2-amine (1.60 g, 8.05 mmol), palladium(II)
acetate (18.1 mg, 0.08 mmol), tri-o-tolylphosphine (98.6 mg, 0.32 mmol), triethylamine
(3.00 mL, 21.5 mmol), and anhydrous acetonitrile (6 mL). The tube was flushed with
nitrogen and sealed. The mixture was stirred and heated at 90°C for 64 h, followed
by further heating at 110°C for 24 h. The resulting brown mixture was cooled to ambient
temperature and concentrated by rotary evaporation. The brown residue was diluted
with water (25 mL) and extracted with CH
2Cl
2 (3 x 25 mL). The combined CH
2Cl
2 extracts were dried (Na
2SO
4), filtered, concentrated by rotary evaporation, and vacuum dried producing a dark-brown
oil (2.24 g). The crude product was purified by column chromatography on silica gel
(120 g), eluting with ethyl acetate-hexane (3:1, v/v). Fractions containing the product
(R
f 0.21) were combined, concentrated by rotary evaporation, and vacuum dried to give
1.05 g (46.9%) of a light-yellow oil.
(4E)-N-Methyl-5-(5-pyrimidinyl)-4-penten-2-ol
[0135] Under a nitrogen atmosphere, a stirring solution of (4E)-N-methyl-N-(tert-butoxycarbonyl)-5-(5-pyrimidinyl)-4-penten-2-ol
(881.2 mg, 3.18 mmol) in CHCl
3 (55 mL) was treated dropwise at ambient temperature with iodotrimethylsilane (1.41
g, 7.03 mmol). The resulting solution was stirred for 30 min. Methanol (55 mL) was
added, and the solution was stirred for an additional 1 h and was concentrated by
rotary evaporation. With ice-bath cooling, the residue was basified with 10% NaOH
solution (10 mL), treated with saturated NaCl solution (10 mL), and extracted with
CHCl
3 (8 x 10 mL). The combined CHCl
3 extracts were dried (Na
2SO
4), filtered, concentrated by rotary evaporation, followed by further drying under
high vacuum producing a light-brown oil (0.50 g). The crude product was purified by
column chromatography on silica gel (50 g), eluting with CH
3OH-NH
4OH (20:1, v/v). Fractions containing the product (R
f 0.43) were combined, concentrated by rotary evaporation, and the residue was dissolved
in CHCl
3. The CHCl
3 solution was dried (Na
2SO
4), filtered, concentrated by rotary evaporation, and vacuum dried affording 306.4
mg (54.4%) of a light-amber oil.
(4E)-N-Methyl-5-(5-pyrimidinyl)-4-penten-2-amine Hemigalactarate
[0136] To a warm solution of (4E)-N-methyl-5-(5-pyrimidinyl)-4-penten-2-amine (258.6 mg,
1.46 mmol) in absolute ethanol (2.3 mL) was added galactaric acid (153.3 mg, 0.73
mmol). Water (0.8 mL) was added, and the solution was heated to near reflux until
most of the solids dissolved. The solution was filtered through glass wool to remove
a few white, insoluble particles, washing the filter plug with a warm solution of
ethanol-water (4:1, v/v) (1.1 mL). The filtrate was diluted with ethanol (6.5 mL),
cooled to ambient temperature, and further cooled at 5°C for 48 h. The white precipitate
was filtered, washed with cold ethanol, and vacuum dried at 40°C for 18 h. The yield
was 390.6 mg (94.8%) of a fluffy, white, crystalline powder, mp 164-167°C.
[0137] Sample No. 11 is determined to exhibit a log P of 0.571, and such a favorable log
P value indicates that the compound has the capability of passing the blood-brain
barrier. The sample exhibits a Ki of 179 nM. The low binding constant indicates that
the compound exhibits good high affinity binding to certain CNS nicotinic receptors.
[0138] Sample No. 11 exhibits an EC
50 value of 1500 nM and an E
max value of 80% for dopamine release, indicating that the compound effectively induces
neurotransmitter release thereby exhibiting known nicotinic pharmacology. The sample
exhibits an EC
50 value of 100000 nM and an E
max value of 0% in the rubidium ion flux assay, indicating that the compound exhibits
selective effects at certain CNS nicotinic receptors.
[0139] Sample No. 11 exhibits an E
max of 0% (at a concentration of 100
uM) at muscle-type receptors, indicating that the compound does not induce activation
of muscle-type receptors. The sample exhibits an E
max of 13% (at a concentration of 100
uM) at ganglionic-type receptors. The compound has the capability to activate human
CNS receptors without activating muscle-type and ganglionic-type nicotinic acetylcholine
receptors to any significant degree. Thus, there is provided a therapeutic window
for utilization in the treatment of CNS disorders.
[0140] The foregoing is illustrative of the present invention and is not to be construed
as limiting thereof.