[0001] This invention relates to new, therapeutically useful imidazole derivatives, to a
process for their production and to pharmaceutical compositions containing them.
[0002] The new imidazole derivatives of the present invention are the compounds of the general
formula I hereinafter depicted, wherein the symbols R¹ are the same or different and
each represents a halogen atom or an alkyl or alkoxy group containing from 1 to 3
carbon atoms, the symbols n are the same or different and each represents 0 or an
integer from 1 to 5, the symbols R² are the same or different and each represents
a hydrogen atom or an alkyl group containing from 1 to 3 carbon atoms, and the symbols
R³ are the same or different and each represents a hydrogen atom or an alkyl group
containing from 1 to 3 carbon atoms optionally substituted by one or more halogen
atoms, by a hydroxy or acyloxy group, by an alkoxy group containing from 1 to 3 carbon
atoms which itself is optionally substituted by a hydroxy or acyloxy group, or by
a phenyl group which itself is optionally substituted by one or more substituents
selected from halogen atoms and alkyl and alkoxy groups each containing up to 3 carbon
atoms, or together the symbols R³ and the carbon atom to which they are both attached
form a cycloalkane or cycloalkene group containing from 5 to 7 carbon atoms, and pharmaceutically
acceptable salts thereof.
[0003] In the above definition of R³ the term "acyloxy" preferably means an alkanoyloxy
group containing up to 6 carbon atoms or a benzoyloxy group.
[0004] By the term "pharmaceutically acceptable salts" as used in this specification is
meant acid addition salts the anions of which are relatively innocuous to the animal
organism when used in therapeutic doses so that the beneficial pharmaceutical properties
of the parent compounds of formula I are not vitiated by side-effects ascribable to
those anions.
[0005] Suitable acid addition salts for use in pharmaceuticals may be selected from salts
derived from inorganic acids, for example hydrochlorides, hydrobromides, phosphates,
sulphates and nitrates, and organic acids, for example oxalates, lactates, tartrates,
acetates, salicylates, citrates, propionates, succinates, fumarates, maleates, methylene-bis-β-hydroxynaphthoates,
gentisates and di-
p-toluoyltartrates.
[0006] In this specification reference to compounds of formula I is intended to include
reference to their pharmaceutically acceptable salts, where the context so permits.
[0007] As will be apparent to those skilled in the art, some of the compounds of formula
I exhibit optical and/or geometric isomerism. All such forms, and their mixtures,
are embraced by the invention.
[0008] Preferably the groups R¹ are identical.
[0009] Preferably the symbols n are identical.
[0010] Preferably n is 0 or 1, and when n is 1 the corresponding group R¹ is preferably
in the para-position of the phenyl group to which it is attached.
[0011] Preferably the groups (R¹)
n on each phenyl ring, including their patterns of substitution on the phenyl rings
in relation to the points of attachment of the phenyl rings to the rest of the molecule,
are identical.
[0012] Preferably at least one of each geminal pair of symbols R² represents a hydrogen
atom, and preferably symbols R² which do not represent hydrogen atoms are identical.
[0013] Compounds in which R¹ is halogen or alkyl and R² and R³ are hydrogen or alkyl are
also preferred.
[0014] Especially important compounds of the present invention include those wherein at
least one of the symbols has a value selected from the following:-
(i) n represents 0 or 1;
(ii) R¹ represents a methyl or methoxy group;
(iii) R² represents a hydrogen atom or a methyl group;
(iv) R³ represents a hydrogen atom or an alkyl group containing 1 or 2 carbon atoms
optionally substituted by a hydroxy, acyloxy, e.g. acetoxy, methoxy or phenyl group,
or together the symbols R³ and the carbon atom to which they are both attached form
a cyclohexane or cyclohexene group;
the other symbols being as hereinbefore defined, and pharmaceutically acceptable
salts thereof.
[0015] Particularly important compounds according to the invention include the following:-
A 2-(1,3-dioxan-2-yl)-4,5-diphenylimidazole;
B 2-(5,5-dimethyl-1,3-dioxan-2-yl)-4,5-diphenylimidazole;
C (±)-cis/trans-2-(4,6-dimethyl-1,3-dioxan-2-yl)-4,5-diphenylimidazole;
D r-2-(4,5-diphenylimidazol-2-yl)-c-5-hydroxymethyl-5-methyl-1,3-dioxane;
E r-2-(4,5-diphenylimidazol-2-yl)-t-5-hydroxymethyl-5-methyl-1,3-dioxane;
F r-2-(4,5-diphenylimidazol-2-yl)-5-ethyl-c-5-hydroxymethyl-1,3-dioxane;
G r-2-(4,5-diphenylimidazol-2-yl)-t-5-methoxymethyl-5-methyl-1,3-dioxane;
H r-2-(4,5-diphenylimidazol-2-yl)-c-5-methoxymethyl-5-methyl-1,3-dioxane;
I r-2-(4,5-diphenylimidazol-2-yl)-5-ethyl-c-5-methoxymethyl-1,3-dioxane;
J cis-5-benzyl-2-(4,5-diphenylimidazol-2-yl)]-1,3-dioxane;
K trans-5-benzyl-2-(4,5-diphenylimidazol-2-yl)]-1,3-dioxane;
L 2-(4,5-diphenylimidazol-2-yl)-1,3-dioxane-5-spiro-cyclohexane;
M 2-(4,5-diphenylimidazol-2-yl)-1,3-dioxane-5-spiro-cyclohex-3′-ene;
N 5,5-bis(ethoxymethyl)-2-(4,5-diphenylimidazol-2-yl)-1,3-dioxane;
O 2-(4,5-diphenylimidazol-2-yl)-5,5-diethyl-1,3-dioxane;
P 2-[4,5-bis(4-methoxyphenyl)imidazol-2-yl]-5,5-dimethyl-1,3-dioxane;
Q 2-[4,5-bis(4-methylphenyl)imidazol-2-yl]-5,5-dimethyl-1,3-dioxane;
R t-5-acetoxymethyl-r-2-(4,5-diphenylimidazol-2-yl)-5-methyl-1,3-dioxane; and
S 2-(4,5-diphenylimidazol-2-yl)-5,5-bis(hydroxymethyl)-1,3-dioxane.
[0016] The letters A to S are allocated for easy reference later in this specification.
[0017] The compounds according to the invention are inhibitors of acyl coenzyme-A:cholesterol-O-acyl
transferase (ACAT;EC 2.3.1.26). They are therefore of value as anti-atherosclerotic
agents and have utility in the treatment or prevention of conditions such as atherosclerosis,
hyperlipidaemia, cholesterol ester storage disease and atheroma in vein grafts.
[0018] In assays performed
in vitro microsomes, prepared from the livers of rats fed a diet supplemented with 0.5%w/w
cholesterol and 0.25%w/w cholic acid for 7 days, were incubated with radiolabelled
oleoyl-CoA in the presence of compounds according to the invention at a concentration
of 1µg/ml. The degree of ACAT inhibition produced is shown in Table 1.
[0019] In
in vivo tests, using rats fed on a similar diet to that above and further supplemented by
0.03%w/w of test compound, compounds according to the invention inhibited increases
in plasma cholesterol level, measured after 3 days, relative to control animals fed
on the cholesterol supplemented diet without the drug, as shown in Table 1. Values
of 100% or more indicate plasma cholesterol concentrations that were similar to those
of control rats fed on a normal (non-supplemented) diet.
Table 1
Compound |
In-vitro |
In-vivo |
|
% Inhibition |
% Reduction |
A |
94 |
86 |
B |
95 |
105 |
C |
74 |
|
[0020] Compounds of formula I can be prepared by the application or adaptation of known
methods, by which is meant methods used heretofore or described in the literature.
[0021] According to a feature of the present invention, compounds of general formula I are
prepared by the replacement by hydrogen of the group R⁴ of a compound of the general
formula II hereinafter depicted, wherein R¹, R², R³ and n are as hereinbefore defined
and R⁴ represents a protecting group, for example a benzyl group, by the application
or adaptation of known methods. For example, when R⁴ is a benzyl group it is replaced
by a hydrogen atom preferably by treatment with sodium in liquid ammonia.
[0022] Compounds of formula II may be prepared by the reaction of compounds of the general
formula III hereinafter depicted with compounds of the general formula:-
HOC(R²)₂C(R³)₂C(R²)₂OH IV
wherein R² and R³ are as hereinbefore defined. The reaction is generally carried out
in an inert organic solvent in the presence of an acidic catalyst. Conveniently, the
reaction is carried out in toluene as the solvent, with pyridinium 4-toluenesulphonate
as the acidic catalyst, and at the reflux temperature, with azeotropic removal of
water.
[0023] Alternatively, compounds of formula II wherein R³ represents an alkyl group substituted
by an alkoxy group can be prepared by the alkylation of corresponding compounds of
formula II wherein one or both of the symbols R³ represents an alkyl group substituted
by a hydroxy group, the other symbols being as hereinbefore defined, by the application
or adaptation of known methods, for example by reaction with sodium hydride followed
by reaction with the appropriate alkyl halide.
[0024] Compounds of formula II wherein one or, more especially, both of the groups R³ contain
one or more moieties of the formula -CH₂OH, the other symbols being as hereinbefore
defined, are preferably prepared by the reduction of corresponding compounds containing
a group of the formula -COOR⁵ (wherein R⁵ represents an alkyl group of up to three
carbon atoms, preferably ethyl or methyl) in place of the or each of the said moieties.
The reduction may be carried out by the application or adaptation of known methods,
for example by means of lithium aluminium hydride.
[0025] The compounds obtained by the abovementioned processes, including the intermediates,
can be purified by the usual physical methods, in particular crystallisation and chromatography,
especially to resolve mixtures of enantiomers, for example using a chiral column.
[0026] According to a further feature of the present invention, compounds of general formula
I are prepared by the interconversion of other compounds of general formula I. For
example, compounds containing acyloxy groups can be prepared by the acylation of compounds
containing hydroxy groups by the application or adaptation of known methods, for example
by reaction with the appropriate acid anhydride, optionally in an inert solvent, e.g.
dichloromethane, and optionally in the presence of a catalyst, such as 4-dimethylaminopyridine.
[0027] According to a further feature of the invention, acid addition salts of compounds
of formula I are prepared by reaction of the parent compounds of formula I with the
appropriate acid, for example in an ethereal medium, e.g. tetrahydrofuran, diethyl
ether or a mixture thereof.
[0028] As well as being useful in themselves as active compounds, acid addition salts of
compounds of formula I are useful for the purposes of purification of the parent compounds
of formula I, for example by exploitation of the solubility differences between the
salts and the parent compounds, by techniques well known to those skilled in art.
The parent compounds of formula I can be regenerated from their acid addition salts
by known methods, for example by treatment with an alkali, e.g. aqueous sodium bicarbonate
solution or aqueous ammonia solution.
[0029] N-Benzylimidazoles of formula (III) may be prepared according to the method of H.J.M.
Dou and J. Metzger, Bull. Soc. Chim. Fr.,
1976, 1861.
![](https://data.epo.org/publication-server/image?imagePath=1991/17/DOC/EPNWA1/EP90402636NWA1/imgb0001)
[0030] The following Examples illustrate the preparation of the compounds according to the
invention and the Reference Examples illustrate the preparation of the intermediates.
[0031] In the nuclear magnetic resonance spectra (NMR) the chemical shifts are expressed
in ppm relative to tetramethylsilane. Abbreviations have the following significances:-
s = singlet; d = doublet; t = triplet; q = quartet; m = multiplet; dd = doublet of
doublets; dt = doublet of triplets. Infra-red spectra (IR) were obtained using the
potassium bromide disc method.
EXAMPLE 1
Compound A
[0032] Liquid ammonia (100ml) was condensed into a solution of 1-benzyl-2-(1,3-dioxan-2-yl)-4,5-diphenylimidazole
(5.5g; prepared as described in Reference Example 2) in anhydrous tetrahydrofuran
(100ml). Small pieces of sodium were added portionwise to this mixture until TLC analysis
(ethyl acetate) showed that reaction was complete.
[0033] The mixture was treated with solid ammonium chloride (5g). After the ammonia had
evaporated the mixture was partitioned between saturated aqueous ammonium chloride
solution (100ml) and ethyl acetate (100ml). The layers were separated and the organic
layer was dried over magnesium sulphate and evaporated. Crystallisation of the residue
from a mixture of toluene and cyclohexane (1:1v/v) gave 2-(1,3-dioxan-2-yl)-4,5-diphenylimidazole
(3.0g) in the form of cream-coloured crystals, m.p. 203-205°C. [Elemental analysis:-
C,74.9;H,5.9;N,9.1%; calculated:- C,74.5;H,5.9;N,9.2%; NMR (CDCl₃):- 1.44 and 2.06-2.36
(2H,2m), 3.98 (2H,dt,J=14Hz and 3Hz), 4.23 (2H,dd,J=12Hz and 6Hz), 5.72 (1H,s), 7.30
& 7.50 (10H,m); IR (KBr):- 696, 1109, 1360 and 3433cm⁻¹].
EXAMPLE 2
Compound B
[0034] By proceeding in a manner similar to that described in Example 1, but replacing the
1-benzyl-2-(1,3-dioxan-2-yl)-4,5-diphenylimidazole by the appropriate quantity of
1-benzyl-2-(5,5-dimethyl-1,3-dioxan-2-yl)-4,5-diphenylimidazole, prepared as described
in Reference Example 2, there was prepared 2-(5,5-dimethyl-1,3-dioxan-2-yl)-4,5-diphenylimidazole,
m.p.. 166-167°C. [Elemental analysis:- C,75.9;H,6.8;N,8.5%; calculated:- C,75.4;H,6.6;N,8.4%;
NMR (CDCl₃):- 1.79 & 2.29 (6H,2s), 3.73 (4H,q,J=12Hz), 5.64 (1H,s), 7.2-7.6 (10H,m);
IR (KBr):- 695, 764, 1018, 1106, 1469, 2847 and 2952cm⁻¹].
EXAMPLE 3
Compound C
[0035] By proceeding in a manner similar to that described in Example 1, but replacing the
1-benzyl-2-(1,3-dioxan-2-yl)-4,5-diphenylimidazole by the appropriate quantity of
(±)-cis/trans-1-benzyl-2-(4,6-dimethyl-1,3-dioxan-2-yl)-4,5-diphenylimidazole, prepared
as described in Reference Example 2, there was prepared (±)-cis/trans-2-(4,6-dimethyl-1,3-dioxan-2-yl)-4,5-diphenylimidazole,
m.p. 205-206°C. [Elemental analysis:- C,75.5;H,6.6;N,8.3%; calculated:- C,75.4;H,6.6;N,8.4%;
NMR (CDCl₃):- 1.32 and 1.35 (6H,2s), 1.25-2.10 (2H,m), 3.94-4.48 (2H,m), 5.78 and
6.18 (1H,2s), 7.20-7.60 (10H,m); IR (KBr):- 697, 765, 1120, 1448, 2971 and 3499cm⁻¹].
EXAMPLE 4
Compounds D, E, F, G, H, I, J, K, L, M, N, O, P and Q
[0036] Liquid ammonia (ca.400ml) was condensed into a solution of r-2-(1-benzyl-4,5-diphenylimidazol-2-yl)-c-5-hydroxymethyl-5-methyl-1,3-dioxane
(4.9g) in anhydrous tetrahydrofuran (50ml). The mixture was carefully treated with
small pieces of sodium until TLC analysis (ethyl acetate) showed that reaction was
complete. The mixture was then treated with solid ammonium chloride (10g). After the
ammonia had evaporated the mixture was treated with saturated aqueous ammonium chloride
solution (100ml) and the mixture was extracted with ethyl acetate (3x100ml). The combined
extracts were washed with water (3x100ml), dried over magnesium sulphate and evaporated.
Crystallisation of the residue from cyclohexane gave r-2-(4,5-diphenylimidazol-2-yl)-c-5-hydroxymethyl-5-methyl-1,3-dioxane
(2,9g) in the form of a colourless solid, m.p. 207-209°C. [Elemental analysis:- C,71.5;H,6.4;N,7.8;H₂O,0.9%;
C₂₁H₂₂N₂O₃:0.2H₂O requires:- C,71.2;H,6.61;N,7.9;H₂O,1.0%; NMR (d6-DMSO):- 0.72 (3H,s),
3.60 (2H,d,J=12Hz), 3.73 (2H,d,J=6Hz), 3.97 (2H,d,J=12Hz), 4.21 (1H,t,J=6Hz), 5.57
(1H,s), 7.2-7.5 (10H,m).
[0037] By proceeding in a similar manner,but replacing the r-2-(1-benzyl-4,5-diphenylimidazol-2-yl)-c-5-hydroxyethyl-5-methyl-1,3-dioxane
by the appropriate quantities of the corresponding substituted 1-benzyl-2-(4,5-diphenylimidazol-2-yl)-1,3-dioxanes,
there were prepared:-
r-2-(4,5-diphenylimidazol-2-yl)-t-5-hydroxymethyl-5-methyl-1,3-dioxane, m.p. 208-210°C.;
r-2-(4,5-diphenylimidazol-2-yl)-5-ethyl-c-5-hydroxymethyl-1,3-dioxane, m.p. 198-200°C.;
r-2-(4,5-diphenylimidazol-2-yl)-t-5-methoxymethyl-5-methyl-1,3-dioxane, m.p. 190-192°C.;
r-2-(4,5-diphenylimidazol-2-yl)-c-5-methoxymethyl-5- methyl-1,3-dioxane, m.p. 138-140°C.;
r-2-(4,5-diphenylimidazol-2-yl)-5-ethyl-c-5-methoxymethyl-1,3-dioxane, m.p.197-199°C.;
cis-5-benzyl-2-(4,5-diphenylimidazol-2-yl)]-1,3-dioxane, m.p. 209-210°C.;
trans-5-benzyl-2-(4,5-diphenylimidazol-2-yl)]-1,3-dioxane, m.p. 160-161°C.;
2-(4,5-diphenylimidazol-2-yl)-1,3-dioxane-5-spirocyclohexane, m.p.212-214°C.;
2-(4,5-diphenylimidazol-2-yl)-1,3-dioxane-5-spirocyclohex-3′-ene, m.p. 221-223°C.;
5,5-bis(ethoxymethyl)-2-(4,5-diphenylimidazol-2-yl)-1,3-dioxane, m.p.128-129°C.;
2-(4,5-diphenylimidazol-2-yl)-5,5-diethyl-1,3-dioxane, m.p. 210-212°C.;
2-[4,5-bis(4-methoxyphenyl)imidazol-2-yl]-5,5-dimethyl-1,3-dioxane, m.p. 216-218°C.;
and
2-[4,5-bis(4-methylphenyl)imidazol-2-yl]-5,5-dimethyl-1,3-dioxane, m.p. 206-209°C..
EXAMPLE 5
Hydrochlorides of Compounds D, B and E
[0038] A solution of r-2-(4,5-diphenylimidazol-2-yl)-c-5-hydroxymethyl-5-methyl-1,3-dioxane
(1.7g) in anhydrous tetrahydrofuran (30ml) was treated slowly dropwise with saturated
ethereal hydrogen chloride solution (60ml). The resulting mixture was allowed to stand
at room temperature for 20 minutes, and then the white precipitate was filtered off
and washed with a small quantity of anhydrous diethyl ether, to give r-2-(4,5-diphenylimidazol-2-yl)-c-5-hydroxymethyl-5-methyl-1,3-dioxane
hydrochloride (1.58g), m.p. 275-277°C. (with decomposition). [Elemental analysis:-
C,62.7;H,5.9;N,7.1;Cl,12.8%; C₂₁H₂₂N₂O₃:HCl requires:- C,62.8;H,5.9;N,7.0;Cl,12.4%;
NMR (d6-DMSO):- 0.73 (3H,s), 3.66 (2H,s), 3.73 (2H,d,J=12Hz), 4.04 (2H,d,J=12Hz),
6.08 (1H,s), 7.44 (10H,s)].
[0039] By proceeding in a similar manner, but using 2-(5,5-dimethyl-1,3-dioxan-2-yl)-4,5-diphenylimidazole
and r-2-(4,5-diphenylimidazol-2-yl)-t-5-hydroxymethyl-5-methyl-1,3-dioxane, respectively,
there were prepared 2-(5,5-dimethyl-1,3-dioxan-2-yl)-4,5-diphenylimidazole hydrochloride,
m.p. 225-227°C., and r-2-(4,5-diphenylimidazol-2-yl)-t-5-hydroxymethyl-5-methyl-1,3-dioxane
hydrochloride, m.p. 262-264°C.
EXAMPLE 6
Compound R
[0040] A stirred solution of r-2-(4,5-diphenylimidazol-2-yl)-t-5-hydroxymethyl-5-methyl-1,3-dioxane
(2.7g) in dichloromethane at 0°C. was treated with acetic anhydride (5ml) dropwise
during a period of 15 minutes. The mixture was then treated with 4-dimethylaminopyridine
(50mg) and stirred at room temperature for one hour. It was then washed with water
(3x100ml), dried over magnesium sulphate, and concentrated to dryness. The resulting
residue was recrystallised from ethyl acetate and washed with cyclohexane, to give
to give t-5-acetoxymethyl-r-2-(4,5-diphenylimidazol-2-yl)-5-methyl-1,3-dioxane (2.4g),
in the form of a white solid, m.p. 191-193°C.
EXAMPLE 7
Compound S
[0041] By proceeding in a manner similar to that described hereinbefore in Example 4, but
using 2-(1-benzyl-4,5-diphenylimidazol-2-yl)-5,5-bis(hydroxymethyl)-1,3-dioxane (prepared
as described in Reference Example 6) as starting material, there was prepared 2-(4,5-diphenylimidazol-2-yl)-5,5-bis(hydroxymethyl)-1,3-dioxane,
m.p. 228-230°C.
REFERENCE EXAMPLE 1
[0042] A solution of 1-benzyl-4,5-diphenylimidazole (2.0g) in anhydrous tetrahydrofuran
(25ml) was flushed with argon and cooled in a bath of solid carbon dioxide and acetone
(internal temperature below -70°C). Butyllithium (2.5M solution in hexane; 3.2ml)
was added dropwise over 5 minutes, maintaining the internal temperature at less than
-60°C. The resulting black solution was stirred in the cooling bath for 10 minutes,
then 1-formylmorpholine (1.5g) was added dropwise during 1-2 minutes, again keeping
the internal temperature at less than -60°C. The cooling bath was removed and the
now almost colourless solution was allowed to warm to room temperature during a period
of one hour. The solution was poured into hydrochloric acid (25ml; 2M) and extracted
with ethyl acetate (50ml). The layers were separated and the ethyl acetate layer was
washed with aqueous sodium bicarbonate solution (25ml; 5%w/v), dried over magnesium
sulphate and evaporated. Crystallisation of the light yellow residue from acetone
gave 1-benzyl-2-formyl-4,5-diphenylimidazole (1.0g) in the form of off-white microcrystals,
m.p. 146-147°C.
REFERENCE EXAMPLE 2
[0043] A mixture of 1-benzyl-2-formyl-4,5-diphenylimidazole (6.8g), propane-1,3-diol (7.6g)
and polymer-bound pyridinium 4-toluenesulphonate (1.0g) in toluene (250ml) was stirred
at reflux under a Dean & Stark water trap for 8 hours. TLC analysis (using a 1:1v/v
mixture of ethyl acetate and hexane) showed about 20% unreacted aldehyde. A further
quantity of polymer-bound pyridinium 4-toluenesulphonate (250mg) and propane-1,3-diol
(3.5g) were added and the mixture was heated at reflux continued for a further period
of 6 hours. After cooling to room temperature the mixture was decanted from the catalyst
and washed with water (3x100ml). The organic solution was dried over magnesium sulphate
and evaporated, to give 1-benzyl-2-(1,3-dioxan-2-yl)-4,5-diphenylimidazole (7.2g),
in the form of a pale pink solid.
[0044] By proceeding in a similar manner, but replacing the propane-1,3-diol by the appropriate
quantities of 2,2-dimethylpropane-1,3-diol and (2-R,S, 4-R,S)-pentane-2,4-diol respectively,
there were prepared 1-benzyl-2-(5,5-dimethyl-1,3-dioxan-2-yl)-4,5-diphenylimidazole
and (±)-cis/trans-1-benzyl-2-(4,6-dimethyl-1,3-dioxan-2-yl)-4,5-diphenylimidazole.
REFERENCE EXAMPLE 3
[0045] A mixture of 1-benzyl-2-formyl-4,5-diphenylimidazole (13.5g), 1,1,1-trishydroxymethylethane
(24g) and pyridinium 4-toluenesulphonate (1.0g) in toluene (400ml) was stirred at
reflux under a Dean & Stark water trap for 7 hours. After cooling to room temperature
the mixture was washed with water (3x200ml), and the organic layer was dried over
magnesium sulphate and evaporated, to give a pale yellow residue (14g) which was subjected
to flash chromatography on silica gel, eluting with a mixture of ethyl acetate and
cyclohexane (1:1v/v) to give, in order of elution:-
recovered 1-benzyl-2-formyl-4,5-diphenylimidazole (1.2g);
r-[1-benzyl-2-(4,5-diphenylimidazol-2-yl)]-c-5-hydroxymethyl-5-methyl-1,3-dioxane
(5.8g); and
r-[1-benzyl-2-(4,5-diphenylimidazol-2-yl)]-t-5-hydroxymethyl-5-methyl-1,3-dioxane
(4.0g).
REFERENCE EXAMPLE 4
[0046] A solution of 2-(1-benzyl-4,5-diphenylimidazol-2-yl)-c-5-hydroxymethyl-5-methyl-1,3-dioxane
(5.0g) in anhydrous dimethylformamide (40ml) was cooled to 5°C. and treated with sodium
hydride (0.65g of an 80% dispersion in oil). The mixture was stirred at room temperature
for 1 hour and then it was treated with methyl iodide (1.7ml). The mixture was stirred
at room temperature for a further 2 hours and then it was partitioned between ethyl
acetate (50ml) and water (50ml). The layers were separated and the aqueous layer was
extracted with ethyl acetate (50ml). The combined organic phases were dried over magnesium
sulphate and evaporated to dryness. Crystallisation of the residue from cyclohexane
gave 2-(1-benzyl-4,5-diphenylimidazol-2-yl)-c-5-methoxymethyl-5-methyl-1,3-dioxane
(2.4g), m.p. 138-140°C.
REFERENCE EXAMPLE 5
[0047] By proceeding in a manner similar to that described hereinbefore in Reference Example
2, but replacing the propane-1,3-diol used as a starting material by the appropriate
quantity of diethyl bis(hydroxymethyl)malonate, there was prepared 2-(1-benzyl-4,5-diphenylimidazol-2-yl)-5,5-diethoxy-1,3-dioxane.
REFERENCE EXAMPLE 6
[0048] A stirred solution of 2-(1-benzyl-4,5-diphenylimidazol-2-yl)-5,5-diethoxy-1,3-dioxane
(6.0g) in dry tetrahydrofuran (200ml) under nitrogen was treated with a solution of
lithium aluminium hydride in tetrahydrofuran (15.7ml; 1.0M) dropwise, during 20 minutes,
and keeping the temperature below 35°C. The mixture was stirred at room temperature
for 2 hours, and then it was treated with aqueous sodium hydroxide solution (8ml;
3%w/v), filtered and evaporated. The resulting residue was recrystallised from ethyl
acetate, to give 2-(1-benzyl-4,5-diphenylimidazol-2-yl)-5,5-bis(hydroxymethyl)-1,3-dioxane
(3.45g) in the form of a colourless crystalline solid, m.p. 186-188°C.
[0049] The present invention also includes within its scope pharmaceutical formulations
which comprise at least one of the compounds of formula I or a pharmaceutically acceptable
salt thereof in association with a pharmaceutically acceptable carrier or coating.
In clinical practice the compounds of the present invention may be administered parenterally,
rectally or orally.
[0050] Solid compositions for oral administration include compressed tablets, pills, powders
and granules. In such solid compositions, one or more of the active compounds is,
or are, admixed with at least one inert diluent such as starch, sucrose or lactose.
The compositions may also comprise, as is normal practice, additional substances other
than inert diluents, e.g. lubricating agents, such as magnesium stearate.
[0051] Liquid compositions for oral administration include pharmaceutically acceptable emulsions,
solutions, suspensions, syrups and elixirs containing inert diluents commonly used
in the art such as water and liquid paraffin. Besides inert diluents such compositions
may comprise adjuvants, such as wetting and suspending agents, and sweetening, flavouring,
perfuming and preserving agents. The compositions according to the invention for oral
administration also include capsules of absorbable material such as gelatin, containing
one or more of the active substances with or without the addition of diluents or excipients.
[0052] Preparations according to the invention for parenteral administration include sterile
aqueous, aqueous-organic, and organic solutions, suspensions and emulsions. Examples
of organic solvents or suspending media are propylene glycol, polyethylene glycol,
vegetable oils such as olive oil and injectable organic esters such as ethyl oleate.
The compositions may also contain adjuvants such as stabilising, preserving, wetting,
emulsifying and dispersing agents. They may be sterilised, for example, by filtration
through a bacteria-retaining filter, by incorporation in the compositions of sterilising
agents, by irradiation or by heating. They may also be manufactured in the form of
sterile solid compositions, which can be dissolved in sterile water or some other
sterile injectable medium immediately before use.
[0053] Solid compositions for rectal administration include suppositories formulated in
accordance with known methods and containing at least one compound of formula (I).
[0054] The percentage of active ingredient in the compositions of the invention may be varied,
it being necessary that it should constitute a proportion such that a suitable dosage
shall be obtained. Obviously, several unit dosage forms may be administered at about
the same time. The dose employed will be determined by the physician, and depends
upon the desired therapeutic effect, the route of administration and the duration
of the treatment, and the condition of the patient. In the adult, the doses are generally
from 0.5 to 70, preferably 1 to 10, mg/kg body weight per day by oral administration.
[0055] The following Composition Example illustrates pharmaceutical compositions according
to the present invention.
COMPOSITION EXAMPLE 1 |
No. 2 size gelatin capsules each containing:- |
2-(5,5-dimethyl-1,3-dioxan-2yl)-4,5-diphenylimidazole |
20 mg |
lactose |
100 mg |
starch |
60 mg |
dectrin |
40 mg |
magnesium stearate |
1 mg |
were prepared in accordance with the usual procedure.