The present invention relates to a method for preparing a compound of formula D-9. The compound of formula D-9 may be useful for making novel opioid receptor modulators of Formula (I).
The opioid receptors were identified in the mid-1970's, and were quickly categorized into three sub-sets of receptors (mu, delta and kappa). More recently the original three types of receptors have been further divided into subtypes. Also known is that the family of opioid receptors are members of the G-protein coupled receptor (GPCR) super-family. More physiologically pertinent are the well established facts that opioid receptors are found throughout the central and peripheral nervous system of many mammalian species, including humans, and that modulation of the respective receptors can elicit numerous, albeit different, biological effects, both desirable and undesirable (
A couple biological effects identified for opioid modulators have led to many useful medicinal agents. Most significant are the many centrally acting mu opioid agonist modulators marketed as analgesic agents to attenuate pain (e.g., morphine), as well as peripherally acting mu agonists to regulate motility (e.g., loperamide). Currently, clinical studies are continuing to evaluate medicinal utility of selective delta, mu, and kappa modulators, as well as compounds possessing combined sub-type modulation. It is envisioned such explorations may lead to agents with new utilities, or agents with minimized adverse side effects relative to currently available agents (examples of side effects for morphine includes constipation, respiratory depression, and addiction potential). Some new GI areas where selective or mixed opioid modulators are currently being evaluated includes potential treatment for various diarrheic syndromes, motility disorders (post-operative ileus, constipation), and visceral pain (post operative pain, irritable bowel syndrome, and inflammatory bowel disorders) (
Around the same time the opioid receptors were identified, the enkephalins were identified as a set of endogenous opioid ligands (
More recently, a series of opioid pseudopeptides containing heteroaromatic or heteroaliphatic nuclei were disclosed, however this series is reported showing a different functional profile than that described in the Schiller works. (
Most recently, works around morphine related structures were reported by Wentland, et al, where carboxamido morphine derivatives and it's analogs were prepared (
It is an object of the present invention to provide a process for making certain instant compounds that may be useful as intermediates in preparing new opioid receptor modulators.
The present invention is directed to a process for producing a compound of formula D-9 from a compound of formula D-1, comprising the steps of:
Also disclosed are compounds of Formula (I)
- R1
- is selected from the group consisting of hydrogen, C1-6alkyl, cycloalkyl, heterocyclyl, aryl(C1-6)alkyl, and heteroaryl(C1-6)alkyl; wherein aryl of aryl(C1-6)alkyl is optionally fused to a heterocyclyl or cycloalkyl; and wherein the cycloalkyl and heterocyclyl of R1 are optionally substituted with C1-6alkyl, hydroxy(C1-6)alkyl, C1-6alkoxy, hydroxy, cyano, amino, C16alkylamino, (C1-6alkyl)2amino, halogen, carboxy, aryl(C16)alkoxycarbonyl, C1-6alkoxycarbonyl, aminocarbonyl, C1-6alkylaminocarbonyl, (C1-6alkyl)2aminocarbonyl, or aminosulfonyl;
and, wherein C1-6alkyl of R1 is optionally substituted with one to three substituents independently selected from the group consisting of C16alkoxy, aryl, cycloalkyl, heterocyclyl, hydroxy, cyano, amino, C16alkylamino, (C1-6alkyl)2amino, halogen, and carboxy;
and wherein the aryl and heteroaryl portion of aryl(C1-6)alkyl and heteroaryl(C1-6)alkyl are optionally substituted with one to three R11 substituents independently selected from the group consisting of C16alkyl; hydroxy(C1-6)alkyl; C1-6alkoxy; aryl(C1-6)alkyl; aryl(C1-6)alkoxy; aryl; heteroaryl optionally substituted with C1-4alkyl; cycloalkyl; heterocyclyl; aryloxy; heteroaryloxy; cycloalkyloxy; heterocyclyloxy; amino; C16alkylamino; (C1-6alkyl)2amino; C3-6cycloalkylaminocarbonyl; hydroxy(C16)alkylaminocarbonyl; arylaminocarbonyl wherein aryl is optionally substituted with carboxy or C1-4alkoxycarbonyl; heterocyclylcarbonyl; carboxy; C1-6alkoxycarbonyl; C1-6alkylcarbonyl; C1-6alkylcarbonylamino; aminocarbonyl; C1-6alkylaminocarbonyl; (C1-6alkyl)2aminocarbonyl; cyano; halogen; trifluoromethyl; trifluoromethoxy; or hydroxy; - R2
- is selected from the group consisting of hydrogen, C1-8alkyl, hydroxy(C18)alkyl, aryl(C1-6)alkoxy(C1-6)alkyl, or aryl(C1-8)alkyl;
wherein the aryl portion of the aryl-containing substituents of R2 are optionally substituted with one to two substituents independently selected from the group consisting of C1-6alkyl, C1-6alkoxy, hydroxy, amino, C1-6alkylamino, (C1-6alkyl)2amino, aminocarbonyl, C16alkylaminocarbonyl, (C1-6alkyl)2aminocarbonyl, cyano, fluoro, chloro, bromo, trifluoromethyl, and trifluoromethoxy; and wherein alkyl and alkoxy substituents of aryl are optionally substituted with hydroxy, amino, C1-6alkylamino, (C1-6alkyl)2amino, or aryl; - A
- is selected from the group consisting of aryl, ring system a-1, a-2, a-3, and a-4, optionally substituted with R3 and R5;
A-B is selected from the group consisting of N-C, C-N, N-N and C-C;
D-E is selected from the group consisting of O-C, S-C, and O-N; - R3
- is one to two substituents independently selected from the group consisting of C1-6alkyl, aryl, aryl(C1-6)alkyl, aryl(C2-6)alkenyl, aryl(C2-6)alkynyl, heteroaryl, heteroaryl(C1-6)alkyl, heteroaryl(C2-6)alkenyl, heteroaryl(C26)alkynyl, amino, C1-6alkylamino, (C1-6alkyl)2amino, arylamino, heteroarylamino, aryloxy, heteroaryloxy, and halogen; wherein the aryl and heteroaryl portion of R3 are optionally substituted with one to five substituents independently selected from the group consisting of C16alkyl, hydroxy(C1-6)alkyl, C1-6alkoxy, aryl(C1-6)alkyl, aryl(C1-6)alkoxy, aryl, aryloxy, heteroaryl(C1-6)alkyl, heteroaryl(C1-6)alkoxy, heteroaryl, heteroaryloxy, arylamino, heteroarylamino, amino, C1-6alkylamino, (C16alkyl)2amino, carboxy(C1-6)alkylamino, carboxy, C1-6alkylcarbonyl, C16alkoxycarbonyl, C1-6alkylcarbonylamino, aminocarbonyl, C16alkylaminocarbonyl, (C1-6alkyl)2aminocarbonyl, carboxy(C16)alkylaminocarbonyl, cyano, halogen, trifluoromethyl, trifluoromethoxy, hydroxy, C1-6alkylsulfonyl, C1-6alkylsulfonylamino, -C(O)-NH-CH(-Rc)-C(O)-NH2, and C1-6alkyl;
wherein C1-6alkyl of R3 is optionally substituted with a substituent selected from the group consisting of hydroxy, carboxy, C1-4alkoxycarbonyl, amino, C16alkylamino, (C1-6alkyl)2amino, aminocarbonyl, (C1-4)alkylaminocarbonyl, di(C1-4)alkylaminocarbonyl, aryl, heteroaryl, arylamino, heteroarylamino, aryloxy, heteroaryloxy, aryl(C1-4)alkoxy, and heteroaryl(C1-4)alkoxy; - Rc
- is selected from the group consisting of hydrogen, C1-6alkyl, C16alkylcarbonyl, C1-6alkoxycarbonyl, C1-6alkylcarbonylamino, aryl(C1-6)alkyl, heteroaryl(C1-6)alkyl, aryl, and heteroaryl;
- R4
- is aryl or heteroaryl; wherein R4 is optionally substituted with one to five substituents independently selected from the group R41; wherein R41 is (C16)alkyl, (C1-6)alkoxy, aryl(C1-6)alkoxy, aryl(C1-6)alkylcarbonyloxy, heteroaryl(C1-6)alkylcarbonyloxy, heteroaryl, hydroxy, halogen, aminosulfonyl, formylamino, aminocarbonyl, C1-6alkylaminocarbonyl, (C16alkyl)2aminocarbonyl, heterocyclylcarbonyl, carboxy, or cyano; and wherein C1-6alkyl is optionally substituted with amino, C1-6alkylamino, or (C16alkyl)2amino; and wherein the aryl portion of aryl(C1-6)alkylcarbonyloxy is optionally substituted with one to four substituents independently selected from the group consisting of (C1-6)alkyl, (C1-6)alkoxy, halogen, cyano, amino, and hydroxy;
- R5
- is a substituent on a nitrogen atom contained in ring A selected from the group consisting of hydrogen, C1-4alkyl, and aryl;
- R6
- is selected from the group consisting of hydrogen and C1-6alkyl;
- R7
- is selected from the group consisting of hydrogen and C1-6alkyl;
- Ra and Rb
- are substituents independently selected from the group consisting of hydrogen and C1-6alkyl; or, when Ra and Rb are other than hydrogen, Ra and Rb are optionally taken together with the nitrogen to which they are both attached to form a five to eight membered monocyclic ring;
- L
- is selected from the group consisting of O, S, and N(Rd); wherein Rd is hydrogen, C1-6alkyl, or aryl;
Also disclosed are compounds of Formula (I)
- R1
- is selected from the group consisting of hydrogen, C1-6alkyl, cycloalkyl, heterocyclyl, aryl(C1-6)alkyl, and heteroaryl(C1-6)alkyl; wherein when R1 is phenyl(C1-6)alkyl, phenyl is optionally fused to a heterocyclyl or cycloalkyl;
wherein when R1 is C1-2alkyl, said C1-2alkyl is optionally substituted with one to two substituents independently selected from the group consisting of C1-6alkoxy, aryl, cycloalkyl, heterocyclyl, hydroxy, cyano, amino, C16alkylamino, (C1-6alkyl)2amino, trifluoromethyl, and carboxy;
and further, wherein when R1 is C3-6alkyl, said C3-6alkyl is optionally substituted with one to three substituents independently selected from the group consisting of C1-6alkoxy, aryl, cycloalkyl, heterocyclyl, hydroxy, cyano, amino, C1-6alkylamino, (C1-6alkyl)2amino, trifluoromethyl, and carboxy;
wherein the cycloalkyl and heterocyclyl of C1-2alkyl and C3-6alkyl are optionally substituted with one to two substituents independently selected from the group consisting of C1-6alkyl, hydroxy(C1-6)alkyl, C16alkoxy, hydroxy, cyano, amino, C1-6alkylamino, (C1-6alkyl)2amino, trifluoromethyl, carboxy, aryl(C1-6)alkoxycarbonyl, C1-6alkoxycarbonyl, aminocarbonyl, C1-6alkylaminocarbonyl, (C1-6alkyl)2aminocarbonyl, and aminosulfonyl;
furthermore, wherein the cycloalkyl and heterocyclyl of R1 are optionally substituted with one to two substituents independently selected from the group consisting of C1-6alkyl, hydroxy(C1-6)alkyl, C1-6alkoxy, hydroxy, cyano, amino, C1-6alkylamino, (C1-6alkyl)2amino, trifluoromethyl, carboxy, aryl(C1-6)alkoxycarbonyl, C1-6alkoxycarbonyl, aminocarbonyl, C1-6alkylaminocarbonyl, (C1-6alkyl)2aminocarbonyl, and aminosulfonyl;
furthermore, wherein the aryl and heteroaryl portion of the R1 substituents aryl(C1-6)alkyl and heteroaryl(C1-6)alkyl, are optionally substituted with one to three R11 substituents independently selected from the group consisting of C1-6alkyl; hydroxy(C1-6)alkyl; C1-6alkoxy; C6-10aryl(C1-6)alkyl; C6-10aryl(C1-6)alkoxy; C6-10aryl; heteroaryl optionally substituted with one to two substituents independently selected from the group consisting of C1-4alkyl, C1-4alkoxy, and carboxy; cycloalkyl; heterocyclyl; C6-10aryloxy; heteroaryloxy; cycloalkyloxy; heterocyclyloxy; amino; C1-6alkylamino; (C1-6alkyl)2amino; C3-6cycloalkylaminocarbonyl; hydroxy(C16)alkylaminocarbonyl; C6-10arylaminorarbonyl wherein C6-10aryl is optionally substituted with carboxy or C1-4alkoxycarbonyl; heterocyclylcarbonyl; carboxy; C1-6alkylcarbonyloxy; C1-6alkoxycarbonyl; C1-6alkylcarbonyl; C1-6alkylcarbonylamino; aminocarbonyl; C16alkylaminocarbonyl; (C1-6alkyl)2aminocarbonyl; cyano; halogen; trifluoromethyl; trifluoromethoxy; and hydroxy;
provided that no more than one R11 substituent is selected from the group consisting of C6-10aryl(C1-6)alkyl; C6-10aryl(C1-6)alkoxy; C6-10aryl; heteroaryl optionally substituted with one to two substituents independently selected from the group consisting of C1-4alkyl, C14alkoxy, and carboxy; cycloalkyl; heterocyclyl; C6-10aryloxy; heteroaryloxy; cycloalkyloxy; C6-10arylaminocarbonyl, heterocyclylcarbonyl; and heterocyclyloxy; - R2
- is hydrogen, C1-8alkyl, hydroxy(C1-8)alkyl, C6-10aryl(C1-6)alkoxy(C1-6)alkyl, or C6-10aryl(C1-8)alkyl;
wherein the C6-10aryl group in the C6-10aryl-containing substituents of R2 are optionally substituted with one to two substituents independently selected from the group consisting of C1-6alkyl, C1-6alkoxy, hydroxy, amino, C1-6alkylamino, (C1-6alkyl)2amino, aminocarbonyl, C16alkylaminocarbonyl, (C1-6alkyl)2aminocarbonyl, cyano, fluoro, chloro, bromo, trifluoromethyl, and trifluoromethoxy; and, wherein the C1-6alkyl and C1-6alkoxy substituents of aryl are optionally substituted with hydroxy, amino, C1-6alkylamino, (C1-6alkyl)2amino, orC1-6 aryl; - A
- is selected from the group consisting of aryl, ring system a-1, a-2, a-3, and a-4, optionally substituted with R3 and R5;
A-B is selected from the group consisting of N-C, C-N, N-N and C-C;
D-E is selected from the group consisting of O-C, S-C, and O-N;
F-G is selected from the group consisting of N-O and C-O; - R3
- is one to two substituents independently selected from the group consisting of C1-6alkyl, aryl, aryl(C1-6)alkyl, aryl(C2-6)alkenyl, aryl(C2-6)alkynyl, heteroaryl, heteroaryl(C1-6)alkyl, heteroaryl(C2-6)alkenyl, heteroaryl(C26)alkynyl, amino, C1-6alkylamino, (C1-6alkyl)2amino, arylamino, heteroarylamino, aryloxy, heteroaryloxy, trifluoromethyl, and halogen;
wherein the aryl,heteroaryl and the aryl and heteroaryl of aryl(C1-6)alkyl, aryl(C2-6)alkenyl, aryl(C2-6)alkynyl, heteroaryl(C1-6)alkyl, heteroaryl(C26)alkenyl, heteroaryl(C2-6)alkynyl, arylamino, heteroarylamino, aryloxy, and heteroaryloxy, are optionally substituted with one to five fluoro substituents or one to three substituents independently selected from the group consisting of C1-6alkyl, hydroxy(C1-6)alkyl, C1-6alkoxy, C6-10aryl(C16)alkyl, C6-10aryl(C1-6)alkoxy, C6-10aryl, C6-10aryloxy, heteroaryl(C1-6)alkyl, heteroaryl(C1-6)alkoxy, heteroaryl, heteroaryloxy, C6-10arylamino, heteroarylamino, amino, C1-6alkylamino, (C1-6alkyl)2amino, carboxy(C16)alkylamino, carboxy, C1-6alkylcarbonyl, C1-6alkoxycarbonyl, C16alkylcarbonylamino, aminocarbonyl, C1-6alkylaminocarbonyl, (C16alkyl)2aminocarbonyl, carboxy(C1-6)alkylaminocarbonyl, cyano, halogen, trifluoromethyl, trifluoromethoxy, hydroxy, C1-6alkylsulfonyl, and C16alkylsulfonylamino; provided that no more than one such substituent on the aryl or heteroaryl portion of R3 is selected from the group consisting of C6-10aryl(C1-6)alkyl, C6-10aryl(C1-6)alkoxy, C6-10aryl, C6-10aryloxy, heteroaryl(C1-6)alkyl, heteroaryl(C1-6)alkoxy, heteroaryl, heteroaryloxy, C6-10arylamino, and heteroarylamino;
and wherein C1-6alkyl, and C1-6alkyl of aryl(C1-6)alkyl and heteroaryl(C16)alkyl, is optionally substituted with a substituent selected from the group consisting of hydroxy, carboxy, C1-4alkoxycarbonyl, amino, C16alkylamino, (C1-6alkyl)2amino, aminocarbonyl, (C1-4)alkylaminocarbonyl, di(C1-4)alkylaminocarbonyl, aryl, heteroaryl, arylamino, heteroarylamino, aryloxy, heteroaryloxy, aryl(C1-4)alkoxy, and heteroaryl(C1-4)alkoxy; - R4
- is C6-10aryl or a heteroaryl selected from the group consisting of furyl, thienyl, pyrrolyl, oxazolyl, thiazolyl, imidazolyl, pyrazolyl, pyridinyl, pyrimidinyl, pyrazinyl, indolyl, isoindolyl, indolinyl, benzofuryl, benzothienyl, benzimidazolyl, benzthiazolyl, benzoxazolyl, quinolizinyl, quinolinyl, isoquinolinyl and quinazolinyl;
wherein R4 is optionally substituted with one to three R41 substituents independently selected from the group consisting of (C1-6)alkyl optionally substituted with amino, C1-6alkylamino, or (C1-6alkyl)2amino; (C1-6)alkoxy; phenyl(C1-6)alkoxy; phenyl(C1-6)alkylcarbonyloxy wherein the C1-6 alkyl is optionally substituted with amino; a non fused 5-membered-heteroaryl(C1-6)alkylcarbonyloxy; a non fused 5-membered-heteroaryl; hydroxy; halogen; aminosulfonyl; formylamino; aminocarbonyl; C16alkylaminocarbonyl wherein C1-6alkyl is optionally substituted with amino, C1-6alkylamino, or (C1-6alkyl)2amino; (C1-6alkyl)2aminocarbonyl wherein each C1-6alkyl is optionally substituted with amino, C16alkylamino, or (C1-6alkyl)2amino; heterocyclylcarbonyl wherein heterocyclyl is a 5-7 membered nitrogen-containing ring and said heterocyclyl is attached to the carbonyl carbon via a nitrogen atom; carboxy; or cyano; and wherein the phenyl portion of phenyl(C16)alkylcarbonyloxy is optionally substituted with (C1-6)alkyl (C1-6)alkoxy, halogen, cyano, amino, or hydroxy;
provided that no more than one R41 is (C1-6)alkyl substituted with C16alkylamino or (C1-6alkyl)2amino; aminosulfonyl; formylamino; aminocarbonyl; C1-6alkylaminocarbonyl; (C1-6alkyl)2aminocarbonyl; heterocyclylcarbonyl; hydroxy; carboxy; or a phenyl- or heteroaryl-containing substituent; - R5
- is a substituent on a nitrogen atom of ring A selected from the group consisting of hydrogen and C1-4alkyl;
- R6
- is hydrogen or C1-6alkyl;
- R7
- is hydrogen or C1-6alkyl;
- Ra and Rb
- are independently selected from the group consisting of hydrogen, C1-6alkyl, and C1-6alkoxycarbonyl; alternatively, when Ra and Rb are each other than hydrogen, Ra and Rb are optionally taken together with the nitrogen atom to which they are both attached to form a five to eight membered monocyclic ring;
- L
- is selected from the group consisting of O, S, and N(Rd) wherein Rd is hydrogen or C1-6alkyl;
Figure 1 shows a schematic of the protocol to determine visceral hyperalgesia in rats.Figure 2 andFigure 3 each show the effect in rat of Cpd 18 on the hyperalgesic response to colorectal balloon distention following zymosan.
Disclosed are those compounds wherein R4 is C6-10aryl optionally substituted with one to three R41 substituents independently selected from the group consisting of (C1-3)alkyl, (C1-6)alkoxy, phenyl(C1-6)alkoxy; hydroxy; halogen; formylamino; aminocarbonyl; C1-6alkylaminocarbonyl; (C16alkyl)2aminocarbonyl; heterocyclylcarbonyl wherein heterocyclyl is a 5-7 membered nitrogen-containing ring and said heterocyclyl is attached to the carbonyl carbon via a nitrogen atom; carboxy; and cyano; provided that no more than one R41 substituent is formylamino, aminocarbonyl, C1-6alkylaminocarbonyl, (C1-6alkyl)2aminocarbonyl, heterocyclylcarbonyl, hydroxy, carboxy, or a phenyl-containing substituent.
Disclosed are those compounds wherein R4 is phenyl substituted with one to three R41 substituents independently selected from the group consisting of (C1-3)alkyl, (C1-3)alkoxy, phenyl(C1-3)alkoxy, hydroxy, C1-6alkylaminocarbonyl, and aminocarbonyl; provided that no more than one R41 substitutent is aminocarbonyl, C1-6alkylaminocarbonyl, hydroxy, or a phenyl-containing substituent.
Disclosed are those compounds wherein R4 is phenyl substituted at the 4-position with hydroxy, C1-3alkylaminocarbonyl, or aminocarbonyl, and optionally substituted with one to two substituents independently selected from the group consisting of methyl, methoxy, and benzyloxy.
Disclosed are those compounds wherein R4 is phenyl substituted at the 4-position with hydroxy, C1-3alkylaminocarbonyl, or aminocarbonyl, and optionally substituted with one to two methyl substituents.
Disclosed are those compounds wherein R4 is phenyl substituted at the 4-position with hydroxy, C1-3alkylaminocarbonyl, or aminocarbonyl, and substituted at the 2- and 6- positions with methyl substituents.
Disclosed are those compounds wherein R6 is hydrogen or methyl.
Disclosed are those compounds wherein R6 is hydrogen.
Disclosed are those compounds wherein Ra and Rb are independently selected from the group consisting of hydrogen and C1-3alkyl; or, when Ra and Rb are each other than hydrogen or C1-6 alkoxycarbonyl, Ra and Rb are optionally taken together with the nitrogen atom to which they are both attached to form a five to seven membered monocyclic ring.
Disclosed are those compounds wherein Ra and Rb are independently hydrogen or methyl.
Disclosed are those compounds wherein Ra and Rb are each hydrogen.
Disclosed are those compounds wherein L is O.
Disclosed are those compounds that are present in their RR, SS, RS, or SR configuration.
Disclosed are those compounds that are present in their S,S configuration.
Also disclosed are compounds of Formula (Ia):
- R1
- is selected from the group consisting of hydrogen, C1-6alkyl, aryl(C1-4)alkyl, and heteroaryl(C1-4)alkyl;
wherein the aryl and heteroaryl portion of aryl(C1-4)alkyl and heteroaryl(C14)alkyl are optionally substituted with one to three R11 substituents independently selected from the group consisting of C1-6alkoxy; heteroaryl optionally substituted with one to two substituents independently selected from the group consisting of C1-4alkyl, C1-4alkoxy, and carboxy; carboxy; C14alkoxycarbonyloxy; C1-4alkoxycarbonyl; aminocarbonyl; C14alkylaminocarbonyl; C3-6cycloalkylaminocarbonyl; hydroxy(C16)alkylaminocarbonyl; C6-10arylaminocarbonyl wherein C6-10aryl is optionally substituted with carboxy or C1-4alkoxycarbonyl; heterocyclylcarbonyl; cyano; halogen; trifluoromethoxy; and hydroxy; provided that no more than one R11 is heteroaryl (optionally substituted with one to two C1-4alkyl substituents); C6-10arylaminocarbonyl wherein C6-10aryl is optionally substituted with carboxy or C1-4alkoxycarbonyl; or heterocyclylcarbonyl; - R2
- is selected from the group consisting of hydrogen, C1-4alkyl, hydroxy(C14)alkyl, and phenyl(C1-6)alkoxy(C1-4)alkyl;
wherein said phenyl is optionally substituted with one to two substituents independently selected from the group consisting of C1-3alkyl, C1-3alkoxy, hydroxy, cyano, fluorine, chlorine, bromine, trifluoromethyl, and trifluoromethoxy; - R3
- is one to two substituents independently selected from the group consisting of C1-6alkyl, halogen, and aryl; wherein aryl is optionally substituted with one to three substituents independently selected from the group consisting of halogen, carboxy, aminocarbonyl, C1-3alkylsulfonylamino, cyano, hydroxy, amino, C1-3alkylamino, and (C1-3alkyl)2amino;
- R4
- is C6-10aryl optionally substituted with one to three R41 substituents independently selected from the group consisting of (C1-3)alkyl, (C16)alkoxy, phenyl(C1-6)alkoxy; hydroxy; halogen; formylamino; aminocarbonyl; C1-6alkylaminocarbonyl; (C1-6alkyl)2aminocarbonyl; heterocyclylcarbonyl wherein heterocyclyl is a 5-7 membered nitrogen-containing ring and said heterocyclyl is attached to the carbonyl carbon via a nitrogen atom; carboxy; and cyano;
provided that no more than one R41 substituent is formylamino, aminocarbonyl, C1-6alkylaminocarbonyl, (C1-6alkyl)2aminocarbonyl, heterocyclylcarbonyl, hydroxy, carboxy, or a phenyl-containing substituent. - R5
- is hydrogen or methyl;
- Ra and Rb
- are independently hydrogen or C1-3alkyl; or, when Ra and Rb are each other than hydrogen, Ra and Rb are optionally taken together with the nitrogen atom to which they are both attached to form a five to seven membered monocyclic ring;
Also disclosed is a compound of Formula (Ia) wherein:
- R1
- is selected from the group consisting of C6-10aryl(C1-4)alkyl, pyridinyl(C14)alkyl, and furanyl(C1-4)alkyl; wherein C6-10aryl, pyridinyl, and furanyl are optionally substituted with one to three R11 substituents independently selected from the group consisting of C1-3alkoxy; tetrazolyl; carboxy; C13alkoxycarbonyl; aminocarbonyl; C1-4alkylaminocarbonyl; C13alkylaminocarbonyl; C3-6cycloalkylaminocarbonyl; hydroxy(C14)alkylaminocarbonyl; C6-10arylaminocarbonyl wherein C6-10aryl is optionally substituted with carboxy or C1-4alkoxycarbonyl; morpholin-4-ylcarbonyl; cyano; halogen; and trifluoromethoxy; provided that no more than one R11 is C6-10arylaminocarbonyl;
- R2
- is hydrogen or C1-4alkyl;
- R3
- is one to two substituents independently selected from the group consisting of C1-3alkyl, bromo, and phenyl; wherein phenyl is optionally substituted with one to three substituents independently selected from the group consisting of chloro, fluoro, carboxy, aminocarbonyl, and cyano;
- R4
- is phenyl substituted with one to three R41 substituents independently selected from the group consisting of (C1-3)alkyl, (C1-3)alkoxy, phenyl(C13)alkoxy, hydroxy, C1-6alkylaminocarbonyl, and aminocarbonyl; provided that no more than one R41 is aminocarbonyl, C1-6alkylaminocarbonyl, hydroxy, or a phenyl-containing substituent;
- R5
- is hydrogen;
- Ra and Rb
- are independently hydrogen or methyl;
salts thereof.
Disclosed is a compound of Formula (Ia) wherein:
- R1
- is selected from the group consisting of phenyl(C1-3)alkyl, pyridinyl(C1-3)alkyl, and furanyl(C1-3)alkyl; wherein phenyl, pyridinyl, and furanyl are optionally substituted with one to three R11 substituents independently selected from the group consisting of C1-3alkoxy; tetrazolyl, C3-6cycloalkylaminocarbonyl; hydroxy(C1-4)alkylaminocarbonyl; C6-10arylaminocarbonyl wherein C6-10aryl is optionally substituted with carboxy or C1-4alkoxycarbonyl; morpholin-4-ylcarbonyl; chloro; fluoro; trifluoromethoxy; and carboxy;
- R2
- is hydrogen or methyl;
- R3
- is one to two substituents independently selected from the group consisting of methyl and phenyl; wherein phenyl is optionally substituted with one to three substituents independently selected from the group consisting of chloro and carboxy;
- R4
- is phenyl substituted at the 4-position with hydroxy, C1-3alkylaminocarbonyl, or aminocarbonyl, and optionally substituted with one to two substituents independently selected from the group consisting of methyl, methoxy, and benzyloxy;
- R5
- is hydrogen;
- Ra and Rb
- are each hydrogen;
salts thereof.
Disclosed are compounds of Formula (Ib):
Exemplified compounds of the present disclosure include compounds of Formula (Ic):
Also disclosed are compositions comprised of a compound of Formula (Id):
Exemplified compounds of the present disclosure include compounds of Formula (Ie):
Also disclosed are the representative compounds shown in Table V:
Where the compounds according to this disclosure have at least one chiral center, they may accordingly exist as enantiomers. Where the compounds possess two or more chiral centers, they may additionally exist as diastereomers. Where the processes for the preparation of the compounds according to the disclosure give rise to mixtures of stereoisomers, these isomers may be separated by conventional techniques such as preparative chromatography. The compounds may be prepared in racemic form or as individual enantiomers or diasteromers by either stereospecific synthesis or by resolution. The compounds may, for example, be resolved into their component enantiomers or diasteromers by standard techniques, such as the formation of stereoisomeric pairs by salt formation with an optically active acid, such as (-)-di-p-toluoyl-D-tartaric acid and/or (+)-di-p-toluoyl-L-tartaric acid followed by fractional crystallization and regeneration of the free base. The compounds may also be resolved by formation of stereoisomeric esters or amides, followed by chromatographic separation and removal of the chiral auxiliary. Alternatively, the compounds may be resolved using a chiral HPLC column. It is to be understood that all stereoisomers, racemic mixtures, diastereomers and enantiomers thereof are encompassed within the scope of the present disclosure.
During any of the processes for preparation of the compounds of the present disclosure, it may be necessary and/or desirable to protect sensitive or reactive groups on any of the molecules concerned. This may be achieved by means of conventional protecting groups, such as those described in
In general, under standard nomenclature rules used throughout this disclosure, the terminal portion of the designated side chain is described first followed by the adjacent functionality toward the point of attachment. Thus, for example, a "phenylC1-C6 alkylamidoC1-C6alkyl" substituent refers to a group of the formula:
It is intended that the definition of any substituent or variable at a particular location in a molecule be independent of its definitions elsewhere in that molecule. It is understood that substituents and substitution patterns on the compounds of this disclosure can be selected by one of ordinary skill in the art to provide compounds that are chemically stable and that can be readily synthesized by techniques known in the art as well as those methods set forth herein.
An "independently" selected substituent refers to a group of substituents, wherein the substituents may be different. Therefore, designated numbers of carbon atoms (e.g. C1-8) shall refer independently to the number of carbon atoms in an alkyl or cycloalkyl moiety or to the alkyl portion of a larger substituent in which alkyl appears as its prefix root.
As used herein, unless otherwise noted, "alkyl" whether used alone or as part of a substituent group refers to straight and branched carbon chains having 1 to 8 carbon atoms or any number within this range. The term "alkoxy" refers to an -Oalkyl substituent group, wherein alkyl is as defined supra. Similarly, the terms "alkenyl" and "alkynyl" refer to straight and branched carbon chains having 2 to 8 carbon atoms or any number within this range, wherein an alkenyl chain has at least one double bond in the chain and an alkynyl chain has at least one triple bond in the chain. An alkyl and alkoxy chain may be substituted on a carbon atom. In substituent groups with multiple alkyl groups such as (C1-6alkyl)2amino- the C1-6alkyl groups of the dialkylamino may be the same or different.
The term "cycloalkyl" refers to saturated or partially unsaturated, moncyclic or polycyclic hydrocarbon rings of from 3 to 14 carbon atom members. Examples of such rings include, and are not limited to cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl and adamantyl. Alternatively, the cycloalkyl ring may be fused to a benzene ring (benzo fused cycloalkyl), a 5 or 6 membered heteroaryl ring (containing one of O, S or N and, optionally, one additional nitrogen) to form a heteroaryl fused cycloalkyl.
The term "heterocyclyl" refers to a nonaromatic cyclic ring of 5 to 7 members in which 1 to 2 members are nitrogen, or a nonaromatic cyclic ring of 5 to 7 members in which zero, one or two members are nitrogen and up to two members are oxygen or sulfur, wherein, optionally, the ring contains zero to one unsaturated bonds, and, optionally, when the ring is of 6 or 7 members, it contains up to two unsaturated bonds. The term "heterocyclyl" includes a 5 to 7 membered monocyclic heterocyclic ring fused to a benzene ring (benzo fused heterocyclyl), a 5 or 6 membered heteroaryl ring (containing one of O, S or N and, optionally, one additional nitrogen), a 5 to 7 membered cycloalkyl or cycloalkenyl ring, a 5 to 7 membered heterocyclyl ring (of the same definition as above but absent the option of a further fused ring) or fused with the carbon of attachment of a cycloalkyl, cycloalkenyl or heterocyclyl ring to form a spiro moiety. For instant compounds of the disclosure, the carbon atom ring members that form the heterocyclyl ring are fully saturated. Other compounds of the disclosure may have a partially saturated heterocyclyl ring. The term "heterocyclyl" also includes a 5 to 7 membered monocyclic heterocycle bridged to form bicyclic rings. Such compounds are not considered to be fully aromatic and are not referred to as heteroaryl compounds. Examples of heterocyclyl groups include, and are not limited to, pyrrolinyl (including 2H-pyrrole, 2-pyrrolinyl or 3-pyrrolinyl), pyrrolidinyl, 2-imidazolinyl, imidazolidinyl, 2-pyrazolinyl, pyrazolidinyl, piperidinyl, morpholinyl, thiomorpholinyl and piperazinyl.
The term "aryl" refers to an unsaturated, aromatic monocyclic ring of 6 carbon members or to an unsaturated, aromatic polycyclic ring of from 10 to 14 carbon members. Examples of such aryl rings include, and are not limited to, phenyl, naphthalenyl or anthracenyl. Preferred aryl groups for the practice of this disclosure are phenyl and naphthalenyl.
The term "heteroaryl" refers to an aromatic ring of 5 or 6 members wherein the ring consists of carbon atoms and has at least one heteroatom member. Suitable heteroatoms include nitrogen, oxygen or sulfur. In the case of 5 membered rings, the heteroaryl ring contains one member of nitrogen, oxygen or sulfur and, in addition, may contain up to three additional nitrogens. In the case of 6 membered rings, the heteroaryl ring may contain from one to three nitrogen atoms. For the case wherein the 6 membered ring has three nitrogens, at most two nitrogen atoms are adjacent. Optionally, the heteroaryl ring is fused to a benzene ring (benzo fused heteroaryl), a 5 or 6 membered heteroaryl ring (containing one of O, S or N and, optionally, one additional nitrogen), a 5 to 7 membered cycloalkyl ring or a 5 to 7 membered heterocyclo ring (as defined supra but absent the option of a further fused ring). Examples of heteroaryl groups include, and are not limited to, furyl, thienyl, pyrrolyl, oxazolyl, thiazolyl, imidazolyl, pyrazolyl, isoxazolyl, isothiazolyl, oxadiazolyl, triazolyl, thiadiazolyl, pyridinyl, pyridazinyl, pyrimidinyl or pyrazinyl; fused heteroaryl groups include indolyl, isoindolyl, indolinyl, benzofuryl, benzothienyl, indazolyl, benzimidazolyl, benzthiazolyl, benzoxazolyl, benzisoxazolyl, benzothiadiazolyl, benzotriazolyl, quinolizinyl, quinolinyl, isoquinolinyl or quinazolinyl.
The term "arylalkyl" means an alkyl group substituted with an aryl group (e.g., benzyl, phenethyl). Similarly, the term "arylalkoxy" indicates an alkoxy group substituted with an aryl group (e.g., benzyloxy).
The term "halogen" refers to fluorine, chlorine, bromine and iodine. Substituents that are substituted with multiple halogens are substituted in a manner that provides compounds, which are stable.
Whenever the term "alkyl" or "aryl" or either of their prefix roots appear in a name of a substituent (e.g., arylalkyl, alkylamino) it shall be interpreted as including those limitations given above for "alkyl" and "aryl." Designated numbers of carbon atoms (e.g., C1-C6) shall refer independently to the number of carbon atoms in an alkyl moiety or to the alkyl portion of a larger substituent in which alkyl appears as its prefix root. For alkyl, and alkoxy substituents the designated number of carbon atoms includes all of the independent member included in the range specified individually and all the combination of ranges within in the range specified. For example C1-6 alkyl would include methyl, ethyl, propyl, butyl, pentyl and hexyl individually as well as sub-combinations thereof (e.g. C1-2, C1-3, C1-4, C1-5, C2-6, C3-6, C4-6, C5-6, C2-5, etc.).
Representative IUPAC names for the compounds of the present disclosure were derived using the AutoNom version 2.1 nomenclature software program provided by Beilstein Informationssysteme.
Abbreviations used in the instant specification, particularly the Schemes and Examples, are as follows:
Representative compounds of the present disclosure can be synthesized in accordance with the general synthetic methods described below and are illustrated more particularly in the schemes that follow. Since the schemes are an illustration, the invention should not be construed as being limited by the chemical reactions and conditions expressed. The preparation of the various starting materials used in the schemes is well within the skill of persons versed in the art.
The following schemes describe general synthetic methods whereby intermediate and target compounds of the present disclosure may be prepared. Additional representative compounds and stereoisomers, racemic mixtures, diasteromers and enantiomers thereof can be synthesized using the intermediates prepared in accordance to the general schemes and other materials, compounds and reagents known to those skilled in the art. All such compounds, stereoisomers, racemic mixtures, diasteromers and enantiomers thereof are intended to be encompassed within the scope of the present disclosure.
Certain intermediates and compounds of the present disclosure may be prepared according to the process outlined in Scheme A below.
A carboxylic acid of the formula A-1, available either commercially or prepared by reported protocols in the scientific literature, may be coupled to an α-aminoketone using standard peptide coupling conditions with a coupling agent such as EDCI and an additive such as HOBt to provide a compound of formula A-2. Compound A-2 may be condensed with an amine of the formula H2N-R5 or ammonium acetate and cyclized upon heating in acetic acid to a compound of formula A-4.
The protecting group of compound A-4 may be removed using conditions known to those skilled in the art that are appropriate for the particular protecting group to afford a compound of the formula A-6. For instance, hydrogenation in the presence of a palladium catalyst is one method for the removal of a CBZ protecting group, whereas treatment with an acid such as TFA is effective for a BOC group deprotection.
A compound of formula A-6 may be substituted using reductive amination with an appropriately substituted aldehyde or ketone in the presence of a hydride source, such as sodium borohydride or sodium triacetoxyborohydride, provide compounds of formula A-10.
Alternatively, a compound of formula A-3 may be condensed with a dicarbonyl compound of the formula R3(C=O)2R3 and an amine of the formula H2N-R5 upon heating in acetic acid to afford a compound of the formula A-4. When compound A-3 is protected with a BOC group, a by-product of formula A-5 may be produced. Compounds of formula A-4 or A-5 may be treated with a hydride source such as lithium aluminum hydride to give certain compounds of formula A-10.
Similarly, a compound of formula A-7 may be coupled to an α-aminoketone as described above for compounds of formula A-1 to yield the corresponding compounds of formula A-8. A compound of formula A-8 may then be cyclized in the presence of an amine of formula H2N-R5 or ammonium acetate and subsequently deprotected as described above to arrive at compounds of formula A-10.
Certain compounds of the present disclosure may be prepared according to the process outlined in Scheme B below.
More specifically, a compound of formula B-1 (wherein the imidazole nitrogen is substituted with R5, as defined herein, or R5a, a nitrogen protecting group such as SEM, MOM, or the like) may be deprotonated with an organometallic base such as n-butyllithium and then treated with a suitably substituted amide to yield a compound of formula B-2.
Compound B-2 may be brominated to yield a mixture of regioisomers of formula B-3. A compound of formula B-3 may be further elaborated via a reductive amination with an amine of the formula H2N-R1 in the presence of a hydride source as described in Scheme A to afford a compound of formula B-4.
The amine of a compound of formula B-4 may be coupled with a suitable carboxylic acid under standard peptide coupling conditions with a coupling agent such as EDCI and an additive such as HOBt to yield compounds of formula B-5.
Certain R3 substituents of the present disclosure in which a carbon atom is the point of attachment may be introduced into a compound of formula B-5 through a transition metal-catalyzed cross coupling reaction to afford compounds of formula B-6. Suitable palladium catalysts include palladium tetrakis triphenylphosphine and the like. Suitable Lewis acids for the reaction include boronic acids and the like. Compounds protected with R5a may be deprotected under acidic conditions to yield compounds of formula B-7.
In a similar manner, an intermediate B-2 when optionally protected with R5a may be reductively alkylated using methods described above to give a compound of formula B-8, followed by removal of protecting group R5a using conditions described herein to yield a compound of formula B-9.
One skilled in the art will recognize that substituent L (depicted as O in the formulae of Scheme B) may be further elaborated to S or N(Rd) of the present disclosure using conventional, known chemical methods.
Certain compounds of the present disclosure may be prepared according to the process outlined in Scheme C below.
More specifically, a compound of formula A-10, B-8, or B-9 may be elaborated to a compound of formula C-2 through coupling with a suitable carboxylic acid under standard peptide coupling conditions as described above. One skilled in the art will recognize that substituent L in a compound of formula C-2(depicted as O) may be converted to S or N(Rd) of the present disclosure using conventional, known chemical methods.
Suitably substituted carboxylic acids of the present disclosure may either be commercially available or prepared by reported protocols in the scientific literature. Several chemical routes for preparing certain compounds of formula C-1 are outlined below in Schemes D and E.
Specifically, a compound of formula D-1 may be treated with trifluoromethanesulfonic anhydride to afford the triflate compound of formula D-2. A compound of formula D-2 may be converted to a compound of formula D-4 by a variety chemical routes which utilize conventional chemical methods known to those skilled in the art. For example, the bromo group of a compound of formula D-2 may undergo a carboxylation reaction via an initial carbonylation under a carbon monoxide atmosphere in the presence of an appropriate palladium catalyst and DPPF, followed by an aqueous basic workup to afford a compound of formula D-3. Subsequently, the carboxyl group may be converted to a substituent of R41a of formula D-4 using standard peptide coupling conditions. Alternatively, a compound of formula D-4 may be directly prepared via a carbonylation of compound of formula D-2, followed by treatment with HMDS, or a primary or secondary amine.
The compound of formula D-5, known or prepared by known methods, may be treated with EDC in the presence of copper (I) chloride to afford the corresponding alkene of formula D6. A compound of formula D-6 may then undergo a Heck reaction with a compound of formula D-4 in the presence of an appropriate palladium catalyst and phosphino ligand to afford a compound of formula D7. Subsequent hydrogenation of the alkenyl substituent using standard hydrogen reduction methods affords a compound of formula D-8.
Scheme E demonstrates an alternative method for preparing intermediate D-7. A compound of formula E-1 may be elaborated to a compound of formula E-4 using the appropriately adapted synthetic steps described in Scheme D. One skilled in the art will recognize that this transformation may be achieved by manipulation of the reaction sequence. A compound of formula E-4 may be converted to its corresponding nitrile via an aromatic nucleophilic displacement reaction with cyanide anion. One skilled in the art will recognize that a nitrile substituent is a viable synthon for a substituent of R41a.
A compound of formula E-4 may participate in a Horner-Wadsworth-Emmons reaction with a compound of formula E-7 in the presence of an organometallic base such as n-butyllithiium to afford a compound of formula D-7. This intermediate may be further elaborated as described in Scheme D, herein.
Certain compounds of the present disclosure may be prepared according to the process outlined in Scheme F below.
More specifically, a compound of formula F-1, wherein R11 is an alkoxycarbonyl as defined above, may be saponified to its corresponding acid, a compound of formula F-2.
A compound of formula F-3 wherein R11 is a cyano substituent may be elaborated to its corresponding aminocarbonyl, compound F-4 by treatment with hydrogen peroxide in the presence of hydroxide anion. Similarly, when R3 is a cyano-substituted aryl ring, it may be treated as described above to form an aminocarbonyl-substituted aryl ring.
Certain substitutents of R11 may be installed via a palladium catalyzed coupling reaction with an X-substituted precursor. For example, a compound of formula F-5 wherein X is iodide, bromide, tosylate, triflate, or the like may be treated with Zn(CN)2 in the presence of palladium tetrakis triphenylphosphine to give a compound of formula F-6 wherein R11 is cyano.
Treatment of a compound of formula F-5 with Pd(OAc)2 and a ligand such as 1,1-bis(diphenylphosphino) ferrocene under a carbon monoxide atmosphere provides a compound of formula F-6 wherein R11 is a carboxy substituent.
The palladium catalyzed couplings described above may also be used to install cyano, carboxy, and alkoxycarbonyl substituents onto an aryl ring at R3.
Specific compounds were prepared as per the following examples and reaction sequences; the examples and the diagrams depicting the reaction sequences are offered by way of illustration, to aid in the understanding of the invention and should not be construed to limit in any way the invention set forth in the claims which follow thereafter. The instant compounds may also be used as intermediates in subsequent examples to produce additional compounds of the present disclosure. No attempt has been made to optimize the yields obtained in any of the reactions. One skilled in the art would know how to increase such yields through routine variations in reaction times, temperatures, solvents and/or reagents.
Reagents were purchased from commercial sources. Nuclear magnetic resonance (NMR) spectra for hydrogen atoms were measured in the indicated solvent with (TMS) as the internal standard on a Bruker Biospin, Inc. DPX-300 (300 MHz) spectrometer. The values are expressed in parts per million down field from TMS. The mass spectra (MS) were determined on a Micromass Platform LC spectrometer or an Agilent LC spectrometer using electrospray techniques. Microwave accelerated reactions were performed using either a CEM Discover or a Personal Chemistry Smith Synthesizer microwave instrument. Stereoisomeric compounds may be characterized as racemic mixtures or as separate diastereomers and enantiomers thereof using X-ray crystallography and other methods known to one skilled in the art. Unless otherwise noted, the materials used in the examples were obtained from readily available commercial suppliers or synthesized by standard methods known to one skilled in the art of chemical synthesis. The substituent groups, which vary between examples, are hydrogen unless otherwise noted.
A. [1-(2-Oxo-2-phenyl-ethylcarbamoyl)-ethyl]-carbamic acid benzyl ester. To a solution of commercially available N-α-CBZ-L-alanine (2.11 g, 9.5 mmol) in dichloromethane (50 mL) was added 2-aminoacetophenone hydrochloride (1.62g, 9.5 mmol). The resulting solution was cooled to 0°C and N-methylmorpholine (1.15 g, 11 mmol), 1-hydroxybenzotriazole (2.55 g, 18.9 mmol) and 1-[3-(dimethylamino)propyl]-3-ethylcarbodiimide hydrochloride (2.35 g, 12.3 mmol) in that order were added under an Argon atmosphere. The reaction mixture was warmed to room temperature and stirred overnight. The reaction was quenched by addition of saturated aqueous NaHCO3 solution; the separated organic phase was washed with 2N citric acid, saturated NaHCO3 solution and brine, then dried over MgSO4 overnight. After filtration and concentration, the residue was purified by column chromatography on silica gel (eluent, EtOAc:hexane-1:1) to give the pure product: [1-(2-oxo-2-phenyl-ethylcarbamoyl)-ethyl]-carbamic acid benzyl ester (2.68 g, 83 %). 1H NMR (300 MHz, CDCl3): δ 1.46 (3H, d), 4.39 (1 H, m), 4.75 (2H, d), 5.13 (2H, d), 5.40 (1H, m), 7.03 (1 H, m), 7.36 (5H, m), 7.50 (2H, m), 7.63 (1 H, m), 7.97(2H, m). MS(ES+): 341.1 (100%).
B. [1-(4-Phenyl-1H-imidazol-2-yl)-ethyl]-carbamic acid benzyl ester. To a suspension of [1-(2-oxo-2-phenyl-ethylcarbamoyl)-ethyl]-carbamic acid benzyl ester (2.60 g, 7.64 mmol) in xylene (60 mL) was added NH4OAc (10.3 g, 134 mmol) and HOAc (5 mL). The resulting mixture was heated at reflux for 7 h. After being cooled to room temperature, brine was added and the mixture was separated. The aqueous phase was extracted with EtOAc, and the combined organic phases were dried over Na2SO4 overnight. After filtration and concentration, the residue was purified by column chromatography on silica gel (eluent, EtOAc:hexane-1:1) to give the title compound (2.33 g, 95 %). 1H NMR (300 MHz, CDCl3): δ 1.65 (3H, d), 5.06 (1H, m), 5.14 (2H, q), 5.94 (1 H, d), 7.32 (10H, m), 7.59 (2H, d). MS(ES+): 322.2 (100%).
C. 1-(4-Phenyl-1H-imidazol-2-yl)-ethylamine. To a solution of [1-(4-phenyl-1H-imidazol-2-yl)-ethyl]-carbamic acid benzyl ester (1.5 g, 4.67 mmol) in methanol (25 mL) was added 10% palladium on carbon (0.16 g). The mixture was shaken in a hydrogenation apparatus at rt under a hydrogen atmosphere (10 psi) for 8 h. Filtration followed by evaporation to dryness under reduced pressure gave the crude product 1-(4-Phenyl-1H-imidazol-2-yl)-ethylamine (0.88 g, 100%). 1H NMR (300 MHz, CDCl3): δ 1.53 (3H, d), 4.33 (1 H, q), 7.23 (3H, m), 7.37 (2H, m), 7.67 (2H, m). MS(ES+): 188.1 (38%).
D. Isopropyl-[1-(4-phenyl-1H-imidazol-2-yl)-ethyl]-amine. 1-(4-Phenyl-1H-imidazol-2-yl)-ethylamine (0.20 g, 1.07 mmol) and acetone (0.062 g, 1.07 mmol) were mixed in 1,2-dichloroethane (4 mL), followed by the addition of NaBH(OAc)3 (0.34 g, 1.61 mmol). The resulting mixture was stirred at rt for 3 h. The reaction was quenched with saturated NaHCO3 solution. The mixture was extracted with EtOAc and the combined extracts were dried over Na2SO4. Filtration followed by evaporation to dryness under reduced pressure gave the crude isopropyl-[1-(4-phenyl-1H-imidazol-2-yl)-ethyl]-amine (0.23 g, 100%) which was used for the next reaction without further purification. 1H NMR (300 MHz, CDCl3): δ 1.10 (3H, d), 1.18 (3H, d), 1.57 (3H, d), 2.86 (1 H, m), 4.32 (1 H, m), 7.24 (2H, m), 7.36 (2H, m), 7.69 (2H, m). MS(ES+): 230.2 (100%).
E. (2-(4-Hydroxy-2,6-dimethyl-phenyl)-1-{isopropyl-[1-(4-phenyl-1H-imidazol-2-yl)-ethyl]-carbamoyl}-ethyl)-carbamic acid tert-butyl ester. Into a solution of 2-tert-Butoxycarbonylamino-3-(4-hydroxy-2,6-dimethylphenyl)-propionic acid (0.18 g, 0.6 mmol) in DMF (7 mL) was added isopropyl-[1-(4-phenyl-1H-imidazol-2-yl)-ethyl]-amine (0.11 g, 0.5 mmol), 1-hydroxybenzotriazole (0.22 g, 1.6 mmol) and 1-[3-(dimethylamino)propyl]-3-ethylcarbodiimide hydrochloride (0.12 g, 0.6 mmol). The resulting mixture was stirred under an Argon atmosphere at rt overnight. The reaction mixture was extracted with EtOAc and the combined organic extracts were washed sequentially with saturated aqueous NaHCO3 solution, 1 N HCl, saturated aqueous NaHCO3 solution, and brine. The organic phase was then dried over MgSO4, filtered, and the filtrate was concentrated under reduced pressure. The resulting residue was purified by flash column chromatography (eluent: EtOAc) to afford the product (2-(4-hydroxy-2,6-dimethyl-phenyl)-1-{isopropyl-[1-(4-phenyl-1H-imidazol-2-yl)-ethyl]-carbamoyl}-ethyl)-carbamic acid tert-butyl ester (0.13 g, 50%). MS(ES+): 521.5 (100%).
F. 2-Amino-3-(4-hydroxy-2,6-dimethyl-phenyl)-N-isopropyl-N-[1-(4-phenyl-1H-imidazol-2-yl)-ethyl]-propionamide. A solution of (2-(4-hydroxy-2,6-dimethyl-phenyl)-1-{isopropyl-[1-(4-phenyl-1H-imidazol-2-yl)-ethyl]-carbamoyl}-ethyl)-carbamic acid tert-butyl ester (0.13 g, 0.25 mmol) in trifluoroacetic acid (5 mL) was stirred at rt for 2 h. Upon removal of the solvents, the residue was purified by preparative LC and lyophilized to give the TFA salt of the title compound as a white powder (0.042 g). 1H NMR (300 MHz, CDCl3): δ 0.48 (3H, d), 1.17 (3H, d), 1.76 (3H, d), 2.28 (6H, s), 3.19 (2H, m), 3.74 (1 H, m), 4.70 (1 H, m), 4.82 (1 H, q), 6.56 (2H, s), 7.45 (4H, m), 7.74 (2H, m). MS(ES+): 421.2 (100%).
- A. [2-Methyl-1-(2-oxo-2-phenyl-ethylcarbamoyl)-propyl]-carbamic acid tert-butyl ester. Compound 2a was prepared according to Example 1 using the appropriate reagents, starting materials and methods known to those skilled in the art.
- B. [2-Methyl-1-(4-phenyl-1-H-imidazol-2-yl)-propyl]-carbamic acid tert-butyl ester. Following the procedure described in Example 1 for the conversion of Compound 1a to Compound 1b, and using the appropriate reagents and methods known to those skilled in the art, [2-methyl-1-(4-phenyl-1-H-imidazol-2-yl)-propyl]-carbamic acid tert-butyl ester, Cpd 2b, was prepared.
Subsequent to workup, the crude product mixture was subjected to flash silica gel chromatography (eluents: CH2Cl2, followed by 4:1 CH2Cl2/Et2O, then EtOAc). Processing of the fractions afforded 1.08 g (27%) of recovered [2-methyl-1-(2-oxo-2-phenyl-ethylcarbamoyl)-propyl]-carbamic acid tert-butyl ester (Cpd 2a), 1.89 g (50%) of [2-methyl-1-(4-phenyl-1-H-imidazol-2-yl)-propyl]-carbamic acid tert-butyl ester (Cpd 2b), and 0.60 g of a mixture of N-[2-methyl-1-(4-phenyl-1H-imidazol-2-yl)-propyl]-acetamide (Cpd 2c) and acetamide.
Cpd 2c was purified by dissolving it in hot CH3CN and cooling to 0°C. Collection of the precipitate by suction filtration afforded 0.21 g (7%) of N-[2-methyl-1-(4-phenyl-1H-imidazol-2-yl)-propyl]-acetamide, Cpd 2c, as a white powder (HPLC: 100% @ 254 nm and 214 nm). 1H NMR (300 MHz, CDCl3): δ 7.63 (2H, br s), 7.33 (2H, t, J = 7.5 Hz), 7.25 - 7.18 (2H, m), 4.78 (1 H, br s), 2.35 (1H, br m), 2.02 (3H, s), 1.03 (3H, d, J = 6.7 Hz), 0.87 (3H, d, J = 6.7 Hz); MS (ES+) (relative intensity): 258.3 (100) (M+1). - C. Methyl-[2-methyl-1-(4-phenyl-1H-imidazol-2-yl)-propyl]-amine. A solution of [2-methyl-1-(4-phenyl-1-H-imidazol-2-yl)-propyl]-carbamic acid tert-butyl ester (0.095g, 0.30 mmol) in THF (2.0 mL) was added dropwise over 10 min to a refluxing 1.0 M solution of LiAlH4 in THF (3.0 mL). The reaction was maintained at reflux for 2 h, cooled to room temperature, and quenched by sequential treatment with 0.11 mL of cold water (5°C), 0.11 mL of 15% NaOH in aqueous solution, and 0.33 mL of cold water (5°C). The resultant solid was removed by suction filtration and the filtrate (pH 8 - 9) was extracted three times with EtOAc. The combined organic fractions were dried over MgSO4, filtered, and concentrated to afford 0.58 g (84%) of methyl-[2-methyl-1-(4-phenyl-1H-imidazol-2-yl)-propyl]-amine as a light yellow oil (HPLC: 97% @ 254 nm and 214 nm). 1H NMR (300 MHz, CDCl3): δ 7.69 (2H, d, J = 7.4 Hz), 7.36 (2H, t, J = 7.6 Hz), 7.26 (1 H, s), 7.25 - 7.20 (1 H, m), 3.62 (1 H, d, J = 6.3 Hz), 2.35 (3H, s), 2.06 (1 H, m), 0.99 (3H, d, J = 6.7 Hz), 0.89 (3H, d, J = 6.7 Hz); MS (ES+) (relative intensity): 230.2 (100) (M+1).
- D. Ethyl-[2-methyl-1-(4-phenyl-1H-imidazol-2-yl)-propyl]-amine. A solution of N-[2-methyl-1-(4-phenyl-1H-imidazol-2-yl)-propyl]-acetamide (0.077g, 0.30 mmol) in THF (2.0 mL) was added dropwise over 10 min to a refluxing 1.0 M solution of LiAlH4 in THF (3.0 mL). The reaction was maintained at reflux for 11 h, cooled to rt, and quenched by sequential treatment with 0.11 mL of cold water (5°C), 0.11 mL of 15 % NaOH in aqueous solution, and 0.33 mL of cold water (5°C). The resultant solid was removed by suction filtration and the filtrate (pH 8 - 9) was extracted three times with EtOAc. The combined organic fractions were dried over MgSO4, filtered, and concentrated to afford 0.069 g of a 5:1 mixture (determined by 1H NMR) of ethyl-[2-methyl-1-(4-phenyl-1H-imidazol-2-yl)-propyl]-amine and recovered Cpd 2c as a colorless oil (HPLC: peaks overlap). 1H NMR (300 MHz, CDCl3): δ 7.67 (2H, br s), 7.35 (2H, t, J = 7.6 Hz), 7.26 - 7.17 (2H, m), 3.72 (1 H, d, J = 6.0 Hz), 2.56 (2H, dq, J = 13.0, 7.1 Hz), 2.05 (1 H, m), 1.08 (3H, t, J = 7.1 Hz), 0.97 (3H,d, J = 6.7 Hz), 0.89 (3H, d, J = 6.7 Hz); MS (ES+) (relative intensity): 244.2 (100) (M+1). This sample was of sufficient quality to use in the next reaction without further purification.
Methyl-[2-methyl-1-(4-phenyl-1 H-imidazol-2-yl)-propyl]-amine and ethyl-[2-methyl-1-(4-phenyl-1 H-imidazol-2-yl)-propyl]-amine may be substituted for Cpd 1d of Example 1 and elaborated to compounds of the present disclosure with the appropriate reagents, starting materials and purification methods known to those skilled in the art.
A solution of 1-(4-phenyl-1H-imidazol-2-yl)-ethylamine (0.061 g, 0.33 mmol) of Example 1, and 0.55 g (0.33 mmol) of 3,4-dimethoxybenzaldehyde in 5 mL of anhydrous methanol was stirred at room temperature for 1 h and then cooled to about 0-10°C in an ice bath for 1 h. The reaction was treated carefully with 0.019 g (0.49 mmol) of sodium borohydride in one portion and maintained at about 0-10°C for 21 h. Cold 2M aqueous HCl was added dropwise (30 drops), the mixture was stirred for 5 min, and then partially concentrated in vacuo unheated. The residual material was taken up in EtOAc to yield a suspension that was treated with 5 mL of cold 3M aqueous NaOH and stirred vigorously until clear. The phases were separated and the aqueous layer was extracted three times additional with EtOAc. The combined extracts were dried over MgSO4, filtered, and concentrated to afford 0.11 g of (3,4-dimethoxy-benzyl)-[1-(4-phenyl-1 H-imidazol-2-yl)-ethyl]-amine as a light yellow oil (HPLC: 87% @ 254nm and 66% @ 214 nm). MS (ES+) (relative intensity): 338.1 (100) (M+1). This sample was of sufficient quality to use in the next reaction without further purification. The title compound may be substituted for Cpd 1d of Example 1 and elaborated to compounds of the present disclosure with the appropriate reagents, starting materials and purification methods known to those skilled in the art.
- A. {1-[4-(4-Fluoro-phenyl)-1H-imidazol-2-yl]-ethyl}-carbamic acid tert-butyl ester. A mixture of ammonium acetate (19.3 g, 250 mmol) and glacial HOAc (35 mL) was stirred mechanically and heated to about 100°C to give a colorless solution in 5-10 min. After cooling to rt, a solid mixture of N-t-BOC-L-Alaninal (commercially available from Aldrich) and 4-fluorophenyl glyoxal hydrate was added in portions while stirring to give a yellow mixture. The resulting mixture was heated at 100°C for approximately 2 h before cooling to rt. The mixture was cooled to 0-5°C, then basified by dropwise addition of conc. NH4OH (25 mL), H2O (25 mL), and EtOAc (40 mL), and additional conc. NH4OH (50 mL) to render the mixture alkaline. The phases were separated and the aqueous phase was re-extracted with EtOAc. The combined organic phases were filtered through dicalite to remove an orange solid and were washed with saturated aqueous NaCl. The organic phase was then dried over MgSO4, filtered, and concentrated under reduced pressure to give 4.27 g of an orange-brown residue. The residue was dissolved in a solution of MeCN (22 mL) and DMSO (3 mL) then purified by preparative HPLC on a Kromasil 10u C18 250 x 50 mm column, eluting with a 35:65 MeCN:H2O gradient. The pure fractions were combined and lyophilized to give 1.77 g of the product as a yellow-white powder (42%; TFA salt). MS: m/z 306.1 (MH+).
- B. 1-[4-(4-Fluoro-phenyl)-1H-imidazol-2-yl]-ethylamine. {1-[4-(4-Fluoro-phenyl)-1H-imidazol-2-yl]-ethyl}-carbamic acid tert-butyl ester may be BOC-deprotected using the procedure described in Example 1 for the conversion of Cpd 1e to Cpd 1f. Upon completion of the BOC-deprotection, the resulting amine may be substituted for Cpd 1c of Example 1 and elaborated to compounds of the present disclosure with the appropriate reagents, starting materials and purification methods known to those skilled in the art.
- A. Cpd 5a Regioisomers. Into a cooled solution of 4(5)-phenyl-1-(2-trimethylsilanyl-ethoxymethyl)-1H-imidazole (
Tet. Lett. 1986, 27(35), 4095-8 - B. Cpd 5b Regioisomers. Isopropylamine (0.18 g, 3 mmol) and a regioisomeric mixture of 4(5)-phenyl-1-(2-trimethylsilanyl-ethoxymethyl)-1H-imidazole-2-carbaldehyde (0.91 g, 3 mmol) were mixed in 1,2-dichloroethane (10 mL), followed by addition of sodium triacetoxyborohydride (0.95 g, 4.5 mmol). The resulting mixture was stirred at room temperature for 5 h. The reaction was quenched with saturated aqueous NaHCO3 solution. The resultant mixture was extracted with EtOAc and the combined organic phases were dried over Na2SO4. After filtration and concentration, the residue was purified by flash column chromatography (eluent: CH2Cl2:CH3OH, 7:3) to give isopropyl-[4(5)-phenyl-1-(2-trimethylsilanyl-ethoxymethyl)-1H-imidazol-2-ylmethyl]-amine (0.70 g, 68%) as a mixture of regioisomers. 1H NMR (300 MHz, CDCl3): δ 0.00 (9H, s), 0.94 (2H, t), 1.11 (6H, d), 2.89 (1 H, m), 3.56 (2H, t), 3.94 (2H, s), 5.39 (2H, s), 7.25 (2H, m), 7.37 (2H, m), 7.76 (2H, d). MS(ES+): 346.6 (75%).
Compound 5b may be substituted for Cpd 1d of Example 1 and elaborated to compounds of the present disclosure with the appropriate reagents, starting materials and purification methods known to those skilled in the art.
- A. Cpd 6a Regioisomers. Bromine (1.17 mL, 22.76 mmol) was added slowly to an ice cooled regioisomeric mixture of 4(5)-methyl-1-(2-trimethylsilanyl-ethoxymethyl)-1H-imidazole-2-carbaldehyde (5.47 g, 22.76 mmol;
JOC, 1986, 51(10),1891-4 - B. Cpd 6b Regioisomers. Isopropyl amine (0.30 g, 5 mmol) in 1,2-dichloroethane (2 mL) was added to a 5°C solution of regioisomers Cpd 6a (0.96 g, 3 mmol) in 1,2-dichloroethane (70 mL). After stirring for 5 min, sodium triacetoxyborohydride (1.80 g, 8.5 mmol) was added neat to the reaction mixture. The mixture was gradually warmed to rt and stirred for 24 h. At this time, an additional portion of sodium triacetoxyborohydride (0.60g, 2.8 mmol) was added and the reaction was stirred an additional 16 h. The reaction was then cooled to approximately 10°C and treated while stirring with saturated aqueous NaHCO3. After stirring for 15 min, the layers were separated and the organic phase was dried over Na2SO4, filtered, and concentrated under reduced pressure to give 1.20 g (T.W. 1.09 g) of a regioisomeric mixture, Cpd 6b, as a yellow oil which was used directly without further purification.
- C. Cpd 6c Regioisomers. Isobutyl chloroformate (0.43 g, 3.15 mmol) was added neat to a 0°C solution containing 2-tert-butoxycarbonylamino-3-(4-tert-butoxy-phenyl)-propionic acid (1.21 g, 3.6 mmol; Advanced Chem Tech), N-methylmorpholine (362 µL, 3.3 mmol), and CH2Cl2 (60 mL). After stirring 1.5 h, Cpd 6b (1.09 g, 3 mmol) was added to the reaction mixture. The reaction mixture was then warmed to room temperature and stirred for 16 h. The reaction mixture was then adsorbed on silica gel, and flash chromatographed on a silica gel column eluting with 25% ethyl acetate/hexane. The desired fractions were combined and concentrated under reduced pressure to give 715 mg (35%) of regioisomers of Cpd 6c as a clear oil (TLC: 25% EtOAc/hexane Rf =0.3, homogeneous; HPLC: 100% at 254 and 214 nm, 7.51 min).
- D. Cpd 6d Regioisomers. To the regioisomers of Cpd 6c (90 mg, 0.132 mmol) in 1,2-dimethoxyethane (2 mL) was added phenyl boronic acid (32.2 mg, 0.26 mmol) followed by 2M Na2CO3(aq) (0.53 mL, 1.06 mmol). The resulting mixture was degassed with N2 for 5 min and then palladium tetrakis triphenylphosphine (53 mg, 0.046 mmol) was added neat. The reaction vessel was capped and warmed to 80°C for 14 h with rapid stirring. After cooling to room temperature the mixture was dried over MgSO4, filtered through dicalite, and concentrated under a stream of N2. The residue was dissolved in a small amount of EtOAc and flash chromatographed on a silica gel column (Eluent: 5% - 25% EtOAc/hexane). The desired fractions were concentrated under reduced pressure to yield 55 mg (61%) as regioisomeric mixture of Cpd 6d, which was used without further purification (TLC: 25% EtOAc/hexane Rf=0.3; HPLC: 100% at 254 nm; 88% at 214 nm, 6.50 min).
- E. 2-Amino-3-(4-hydroxy-phenyl)-N-isopropyl-N-(5-methyl-4-phenyl-1H-imidazol-2-ylmethyl)-propionamide Trifluoroacetate (1:2). Trifluoroacetic acid (1 mL) was added to the Cpd 6d regioisomers (55 mg, 0.081 mmol) at room temperature. After 6 h, the excess TFA was removed under a stream of N2. The residue was dissolved in a small amount of acetonitrile and purified by preparative HPLC on a YMC C18 100 x 20 mm column. The purest fractions were combined and lyophilized to give 37 mg (74%) of the title compound as a white lyophil (TLC: 5:1 CHCl3:MeOH Rf=0.55, homogeneous; HPLC: 100% at 214 nm; HPLC/MS: m/z 393 (MH+)). 1H NMR (MeOH-d4) δ 0.85-0.9 (d, 3H), 1.2-1.25 (d, 3H), 2.45 (s, 3H), 3.05-3.1 (t, 2H), 4.0-4.15 (m, 1H), 4.55-4.6 (d, 1 H), 4.7-4.85 (m, 2H), 6.65-6.7 (d, 2H), 6.95-7.0 (d, 2H), 7.45-7.6 (m, 5H).
Using the procedure described in Example 5 and substituting 3,4-dichlorobenzylamine for isopropylamine, (3,4-dichloro-benzyl)-[4(5)-phenyl-1-(2-trimethylsilanyl-ethoxymethyl)-1H-imidazol-2-ylmethyl]-amine was prepared as a pair of regioisomers. A sample (95 mg, 0.21 mmol) of this compound was dissolved in TFA (3 mL) at room temperature. After 2 h the mixture was concentrated under a stream of nitrogen. The residue was purified by reverse phase HPLC, the purest fractions were combined and lyophilized to yield desired product (3,4-dichloro-benzyl)-(4-phenyl-1H-imidazol-2-ylmethyl)-amine as an off white lyophil.
Following the procedure described in Example 1, substituting (3,4-dichloro-benzyl)-(4(5)-phenyl-1H-imidazol-2-ylmethyl)-amine for Cpd 1d, compounds of the present disclosure may be synthesized with the appropriate reagents, starting materials, and purification methods known to those skilled in the art.
- A. (S)-2-tert-Butoxycarbonylamino-3-(2,6-dimethyl-4-trifluoromethanesulfonylphenyl)-propionic acid methyl ester. Into a cool solution of Boc-L-(2,6-diMe)Tyr-OMe (7.0 g, 21.6 mmol; Sources: Chiramer or RSP AminoAcidAnalogues) and N-phenyltrifluoromethanesulfonimide (7.9 g, 22.0 mmol) in dichloromethane (60 mL) was added triethylamine (3.25 mL, 23.3 mmol). The resulting solution was stirred at 0°C for 1 h and slowly warmed to rt. Upon completion, the reaction was quenched by addition of water. The separated organic phase was washed with 1N NaOH aqueous solution, water and dried over Na2SO4 overnight. After filtration and evaporation, the residue was purified by flash column chromatography (eluent: EtOAc-hexane: 3:7) to give the desired product (9.74 g, 99%) as a clear oil; 1H NMR (300 MHz, CDCl3): δ 1.36 (9H, s), 2.39 (6H, s), 3.06 (2H, d, J = 7.7 Hz), 3.64 (3H, s), 4.51-4.59 (1 H, m), 5.12 (1 H, d, J = 8.5 Hz), 6.92 (2H, s); MS (ES+) (relative intensity): 355.8 (100) (M-Boc)+.
- B. (S)-4-(2-tert-Butoxycarbonylamino-2-methoxycarbonylethyl)-3,5-dimethylbenzoic acid. To a suspension of (S)-2-tert-butoxycarbonylamino-3-(2,6-dimethyl-4-trifluoromethanesulfonylphenyl)-propionic acid methyl ester (9.68 g, 21.3 mmol), K2CO3 (14.1 g, 0.102 mol), Pd(OAc)2 (0.48 g, 2.13 mmol) and 1,1'-bis(diphenylphosphino)ferrocene (2.56 g, 4.47 mmol) in DMF (48 mL) was bubbled in gaseous CO for 15 min. The mixture was heated to 60°C for 8 h with a CO balloon. The cool mixture was partitioned between NaHCO3 and EtOAc, and filtered. The aqueous layer was separated, acidified with 10% citric acid aqueous solution, extracted with EtOAc, and finally dried over Na2SO4. Filtration and concentration of the filtrate resulted in a residue. The residue was recrystallized from EtOAc-hexanes to afford the desired product (7.05 g, 94%); 1 H NMR (300 MHz, CDCl3): δ1.36 (9H, s), 2.42 (6H, s), 3.14 (2H, J = 7.4 Hz), 3.65 (3H, s), 4.57-4.59 (1 H, m), 5.14 (1 H, d, J = 8.6 Hz), 7.75 (2H, s); MS(ES+) (relative intensity): 251.9 (100) (M-Boc)+.
- C. (S)-2-tert-Butoxycarbonylamino-3-(4-carbamoyl-2,6-dimethylphenyl)propionic acid methyl ester. Into a stirring solution of (S)-4-(2-tert-butoxycarbonylamino-2-methoxycarbonylethyl)-3,5-dimethylbenzoic acid (3.00 g, 8.54 mmol), PyBOP (6.68 g, 12.8 mmol) and HOBt (1.74 g, 12.8 mmol) in DMF (36 mL) was added DIPEA (5.96 mL, 34.2 mmol) and NH4Cl (0.92 g, 17.1 mmol). The resulting mixture was stirred at rt for 40 min before being partitioned between aqueous NH4Cl solution and EtOAc. The separated organic phase was washed sequentially with 2N citric acid aqueous solution, saturated aqueous NaHCO3 solution, and brine, then dried over Na2SO4 overnight. After filtration and concentration, the residue was purified by flash column chromatography (eluent: EtOAc) to give the product. (3.00 g, 100%); 1H NMR (300 MHz, CDCl3): δ1.36 (9H, s), 2.39 (6H, s), 3.11 (2H, J = 7.2 Hz), 3.65 (3H, s), 4.53-4.56 (1 H, m), 5.12 (1 H, d, J = 8.7 Hz), 5.65 (1 H, br s), 6.09 (1 H, br s), 7.46 (2H, s); MS(ES+) (relative intensity): 250.9 (100) (M-Boc)+.
- D. (S)-2-tert-Butoxycarbonylamino-3-(4-carbamoyl-2,6-dimethylphenyl)propionic acid. Into an ice-cooled solution of methyl ester from Step C (2.99 g, 8.54 mmol) in THF (50 mL) was added an aqueous LiOH solution (1 N, 50 mL) and stirred at 0°C. Upon consumption of the starting materials, the organic solvents were removed and the aqueous phase was neutralized with cooled 1 N HCl at 0°C, and extracted with EtOAc, and dried over Na2SO4 overnight. Filtration and evaporation to dryness led to the title acid (S)-2-tert-butoxycarbonylamino-3-(4-carbamoyl-2,6-dimethylphenyl)propionic acid (2.51 g, 87%); 1H NMR (300 MHz, DMSO-d6): δ 1.30 (9H, s), 2.32 (6H, s), 2.95(1H, dd, J = 8.8, 13.9 Hz), 3.10 (1 H, dd, J = 6.2, 14.0 Hz), 4.02-4.12 (1 H, m), 7.18-7.23 (2H, m), 7.48 (2H, s), 7.80 (1 H, s); MS(ES+) (relative intensity): 236.9 (6) (M-Boc)+.
- A. 2-Methoxy-5-{[1-(4-phenyl-1H-imidazol-2-yl)-ethylamino]-methyl}-benzoic acid methyl ester. Using the procedures described for Example 3, substituting 5-formyl-2-methoxy-benzoic acid methyl ester (
WO 02/22612 - B. 5-({[2-tert-Butoxycarbonylmethyl-3-(4-carbamoyl-2,6-dimethylphenyl)-propionyl]-[1-(4-phenyl-1H-imidazol-2-yl)-ethyl]-amino}-methyl)-2-methoxy-benzoic acid methyl ester. Using the procedure of Example 1 for the conversion of Cpd 1d to Cpd 1e, substituting 2-methoxy-5-{[1-(4-phenyl-1H-imidazol-2-yl)-ethylamino]-methyl}-benzoic acid methyl ester for Cpd 1d and substituting 2-tert-Butoxycarbonylamino-3-(4-carbamoyl-2,6-dimethyl-phenylpropionic acid of Example 8 for 2-tert-Butoxycarbonylamino-3-(4-hydroxy-2,6-dimethyl-phenyl)-propionic acid, Cpd 9a was prepared.
- C. 5-({[2-tert-butoxycarbonylamino-3-(4-carbamoyl-2,6-dimethyl-phenyl)-propionyl]-[1-(4-phenyl-1H-imidazol-2-yl)-ethyl]-amino}-methyl)-2-methoxy-benzoic acid. 5-({[2-tert-Butoxycarbonylmethyl-3-(4-carbamoyl-2,6-dimethyl-phenyl)-propionyl]-[1-(4-phenyl-1H-imidazol-2-yl)-ethyl]-amino}-methyl)-2-methoxy-benzoic acid methyl ester was dissolved in an ice-chilled (0-10°C), mixed solvent system of THF (10 mL) and MeOH (5 mL). A LiOH·H2O/water suspension (2.48 M; 3.77 mL) was added dropwise, then the reaction was allowed to warm to room temperature and stirred overnight. The resulting mixture was cooled in an ice bath and the basic solution was neutralized with 2N citric acid until slightly acidic. The mixture was concentrated under reduced pressure to remove the volatile materials, after which time the remaining aqueous phase was extracted with EtOAc (3 x 26 mL). These combined organic phases were dried over MgSO4, filtered, and concentrated under reduced pressure to give 2.26 g (146% of theory) of pale yellowish white solid. This crude material was dissolved in a 10% MeOH/CH2Cl2 solution and adsorbed onto 30 g of silica. The adsorbed material was divided and chromatographed on an ISCO normal phase column over two runs, using a 40 g Redi-Sep column for both runs. The solvent system was a gradient MeOH/CH2Cl2 system as follows: Initial 100% CH2Cl2, 98%-92% over 40 min; 90% over 12 min, and then 88% over 13 min. The desired product eluted cleanly between 44-61 min. The desired fractions were combined and concentrated under reduced pressure to yield 1.74 g (113% of theory) of 5-({[2-tert-butoxycarbonylamino-3-(4-carbamoyl-2,6-dimethyl-phenyl)-propionyl]-[1-(4-phenyl-1H-imidazol-2-yl)-ethyl]-amino}-methyl)-2-methoxy-benzoic acid, Cpd 9b, as a white solid.
- D. 5-({[2-Amino-3-(4-carbamoyl-2,6-dimethyl-phenyl)-propionyl]-[1-(4-phenyl-1H-imidazol-2-yl)-ethyl]-amino}-methyl)-2-methoxy-benzoic acid. A portion of Cpd 9b (0.27g, 0.41 mmol) was dissolved in EtOAc (39 mL)/ THF (5 mL), filtered, and subsequently treated with gaseous HCl for 15 min. After completion of the HCl addition, the reaction was slowly warmed to room temperature and a solid precipitate formed. After 5 h the reaction appeared >97% complete by LC (@214nm; 2.56 min.). The stirring was continued over 3 d, then the solid was collected and rinsed with a small amount of EtOAc. The resulting solid was dried under high vacuum under refluxing toluene for 2.5 h to yield 0.19 g (71 %) of desired Cpd 9c as a white solid di-HCl salt.
- A. 4-{[1-(4-Phenyl-1H-imidazol-2-yl)-ethylamino]-methyl}-benzoic acid methyl ester. Using the procedure described for Example 3, substituting 4-formyl-benzoic acid methyl ester for 3,4-dimethoxybenzaldehyde, 4-{[1-(4-phenyl-1H-imidazol-2-yl)-ethylamino]-methyl}-benzoic acid methyl ester was prepared.
- B. 4-({[2-Amino-3-(4-hydroxy-2,6-dimethyl-phenyl)-propionyl]-[1-(4-phenyl-1H-imidazol-2-yl)-ethyl]-amino}-methyl)-benzoic acid methyl ester. 4-{[1-(4-phenyl-1H-imidazol-2-yl)-ethylamino]-methyl}-benzoic acid methyl ester was substituted for Cpd 1 d of Example 1 and elaborated according to the procedure of Example 1 to prepare the product.
- C. 4-({[2-Amino-3-(4-hydroxy-2,6-dimethyl-phenyl)-propionyl]-[1-(4-phenyl-1H-imidazol-2-yl)-ethyl]-amino}-methyl)-benzoic acid. A solution of 4-({[2-amino-3-(4-hydroxy-2,6-dimethyl-phenyl)-propionyl]-[1-(4-phenyl-1H-imidazol-2-yl)-ethyl]-amino}-methyl)-benzoic acid methyl ester (TFA salt), (0.043 g, 0.067 mmol) in 5 mL of THF was cooled in an ice bath. A cold (5-10°C) 3M aqueous solution of LiOH (5 mL) was added and the reaction mixture was stirred vigorously while cold. Chilled (5-10°C) 2M aqueous HCl (7.5 mL) was added dropwise to neutralize the mixture was stirred for 5 min, and then partially concentrated in vacuo unheated. The resultant aqueous suspension was extracted seven times with EtOAc. The extracts were dried over Na2SO4, filtered, and concentrated to afford 0.030 g of 4-({[2-amino-3-(4-hydroxy-2,6-dimethyl-phenyl)-propionyl]-[1-(4-phenyl-1H-imidazol-2-yl)-ethyl]-amino}-methyl)-benzoic acid as a white powder. The material was taken up in EtOH and treated with 1 M HCl in Et2O. The solution was concentrated and the residue was triturated with CH3CN. A 0.021 g (53%) sample of 4-({[2-amino-3-(4-hydroxy-2,6-dimethyl-phenyl)-propionyl]-[1-(4-phenyl-1H-imidazol-2-yl)-ethyl]-amino}-methyl)-benzoic acid was collected as its HCl salt. MS (ES+) (relative intensity): 513.2 (100) (M+1).
- A. 3-{[1-(4-phenyl-1H-imidazol-2-yl)-ethylamino]-methyl}-benzonitrile. Using the procedure described for Example 3, substituting 3-formyl-benzonitrile for 3,4-dimethoxybenzaldehyde, the product was prepared.
- B. [1-{(3-Cyano-benzyl)-[1-(4-phenyl-1H-imidazol-2-yl)-ethyl]-carbamoyl}-2-(4-hydroxy-2,6-dimethyl-phenyl)-ethyl]-carbamic acid tert-butyl ester. 3-{[1-(4-phenyl-1H-imidazol-2-yl)-ethylamino]-methyl}-benzonitrile was substituted for Cpd 1 d of Example 1 and elaborated according to the procedure of Example 1 to prepare the product.
- C. [1-{(3-Carbamoyl-benzyl)-[1-(4-phenyl-1H-imidazol-2-yl)-ethyl]-carbamoyl}-2-(4-hydroxy-2,6-dimethyl-phenyl)-ethyl]-carbamic acid tert-butyl ester. A solution of [1-{(3-cyano-benzyl)-[1-(4-phenyl-1H-imidazol-2-yl)-ethyl]-carbamoyl}-2-(4-hydroxy-2,6-dimethyl-phenyl)-ethyl]-carbamic acid tert-butyl ester (0.070 g, 0.12 mmol) in 3 mL of EtOH was treated with 1.0 mL of 30% hydrogen peroxide followed immediately by 0.1 mL of a 6M aqueous solution of NaOH. The reaction mixture was stirred vigorously for 18 h and quenched by pouring into chilled (5-10°C) water. The aqueous solution was extracted five times with Et2O and the combined extracts were dried over MgSO4, filtered, and concentrated to provide 0.051 g of [1-{(3-carbamoyl-benzyl)-[1-(4-phenyl-1H-imidazol-2-yl)-ethyl]-carbamoyl}-2-(4-hydroxy-2,6-dimethyl-phenyl)-ethyl]-carbamic acid tert-butyl ester as a colorless residue (HPLC: 84% @ 254 nm and 77% @ 214 nm). MS (ES+) (relative intensity): 612.5 (100) (M+1). This sample was of sufficient quality to use in the next reaction without further purification.
- D. 3-({[2-Amino-3-(4-hydroxy-2,6-dimethyl-phenyl)-propionyl]-[1-(4-phenyl-1H-imidazol-2-yl)-ethyl]-amino}-methyl)-benzamide. [1-{(3-carbamoyl-benzyl)-[1-(4-phenyl-1H-imidazol-2-yl)-ethyl]-carbamoyl}-2-(4-hydroxy-2,6-dimethyl-phenyl)-ethyl]-carbamic acid tert-butyl ester may be BOC-deprotected using the procedure described in Example 1 for the conversion of Cpd 1e to Cpd 1f to provide the title compound.
- A. {1-[2-(2-Bromo-phenyl)-2-oxo-ethylcarbamoyl]-ethyl}-carbamic acid tert-butyl ester. Compound 2a was prepared according to Example 1 using the appropriate reagents, starting materials and methods known to those skilled in the art.
- B. {1-[4-(2-Bromo-phenyl)-1H-imidazol-2-yl]-ethyl}-carbamic acid tert-butyl ester. Following the procedure described in Example 1 for the conversion of Compound 1a to Compound 1b, and using the appropriate reagents and methods known to those skilled in the art, Cpd 12b, was prepared.
- C. 1-[4-(4-Bromo-phenyl)-1H-imidazol-2-yl]-ethylamine. Using the procedure described for the conversion of Cpd 1e to 1f, Compound 12c was prepared.
- D. [1-[{1-[4-(2-Bromo-phenyl)-1H-imidazol-2-yl]-ethyl}-(3,4-dimethoxy-benzyl)-carbamoyl]-2-(4-carbamoyl-2,6-dimethyl-phenyl)-ethyl]-carbamic acid tert-butyl ester. Using the procedure described in Example 9, Step D, and substituting 1-[4-(4-bromo-phenyl)-1H-imidazol-2-yl]-ethylamine for 1-(4-phenyl-1H-imidazol-2-yl)-ethylamine, the product was prepared.
- E. {2-(4-Carbamoyl-2,6-dimethyl-phenyl)-1-[{1-[4-(2-cyano-phenyl)-1H-imidazol-2-yl]-ethyl}-(3,4-dimethoxy-benzyl)-carbamoyl]-ethyl}-carbamic acid tert-butyl ester. To a solution of [1-[{1-[4-(2-bromo-phenyl)-1H-imidazol-2-yl]-ethyl}-(3,4-dimethoxy-benzyl)-carbamoyl]-2-(4-carbamoyl-2,6-dimethyl-phenyl)-ethyl]-carbamic acid tert-butyl ester (294 mg; 0.4 mmol) in DMF (2 mL) was added Zn(CN)2 (28 mg; 0.24 mmol). The resulting mixture was degassed with Argon for 5 min, then Pd(PPh3)4 (92 mg; 0.08 mmol) was added neat, and the system was immediately warmed to 100°C. After heating for 6 h, the reaction was cooled to rt and partitioned between EtOAc and water. The organic phase was dried over Na2SO4, filtered, and concentrated under reduced pressure. The crude material was subjected to reverse phase HPLC (water/ acetonitrile/ 0.1 % TFA). The fractions of interest were combined, basified with saturated aqueous NaHCO3 and extracted twice with EtOAc. The EtOAc extracts were combined, dried over Na2SO4, filtered, and concentrated to afford 146 mg (54%) of desired {2-(4-carbamoyl-2,6-dimethyl-phenyl)-1-[{1-[4-(2-cyano-phenyl)-1H-imidazol-2-yl]-ethyl}-(3,4-dimethoxy-benzyl)-carbamoyl]-ethyl}-carbamic acid tert-butyl ester (HPLC: 96% @ 254 nm and 97% @ 214 nm). This sample was of sufficient quality to use in the next reaction without further purification.
- F. 4-{2-Amino-2-[{1-[4-(2-cyano-phenyl)-1H-imidazol-2-yl]-ethyl}-(3,4-dimethoxy-benzyl)-carbamoyl]-ethyl}-3,5-dimethyl-benzamide. {2-(4-carbamoyl-2,6-dimethyl-phenyl)-1-[{1-[4-(2-cyano-phenyl)-1H-imidazol-2-yl]-ethyl}-(3,4-dimethoxy-benzyl)-carbamoyl]-ethyl}-carbamic acid tert-butyl ester may be BOC-deprotected using the procedure described in Example 1 for the conversion of Cpd 1e to Cpd 1f to give the title compound.
- A. 1-[4-(3-Bromo-phenyl)-1H-imidazol-2-yl]-ethylamine. Using the procedure described in Example 12, and the appropriately substituted starting materials and reagents, 1-[4-(3-bromo-phenyl)-1H-imidazol-2-yl]-ethylamine was prepared.
- B. {1-[4-(3-Bromo-phenyl)-1H-imidazol-2-yl]-ethyl}-(3,4-dimethoxybenzyl)-amine-. Using the procedure described in Example 3, and substituting 1-[4-(3-bromo-phenyl)-1H-imidazol-2-yl]-ethylamine for 1-(4-phenyl-1H-imidazol-2-yl)-ethylamine, the product was prepared.
- C. [1-[{1-[4-(3-Bromo-phenyl)-1H-imidazol-2-yl]-ethyl}-3,4-dimethoxy-benzyl)-carbamoyl]-2-(4-carbamoyl-2,6-dimethyl-phenyl)-ethyl]-carbamic acid tert-butyl ester. Using the procedure of Example 1 for the conversion of Cpd 1 d to Cpd 1e, substituting {1-[4-(3-Bromo-phenyl)-1H-imidazol-2-yl]-ethyl}-(3,4-dimethoxy-benzyl)-amine for Cpd 1 d and substituting 2-tert-Butoxycarbonylamino-3-(4-carbamoyl-2,6-dimethyl-phenyl-propionic acid of Example 8 for 2-tert-Butoxycarbonylamino-3-(4-hydroxy-2,6-dimethylphenyl)-propionic acid, the product was prepared.
- D. 3-(2-{1-[[2-tert-Butoxycarbonylamino-3-(4-carbamoyl-2,6-dimethyl-phenyl)-propionyl]-(3,4-dimethoxy-benzyl)-amino]-ethyl}-1H-imidazol-4-yl)-benzoic acid. To a solution of [1-[{1-[4-(3-bromo-phenyl)-1H-imidazol-2-yl]-ethyl}-(3,4-dimethoxy-benzyl)-carbamoyl]-2-(4-carbamoyl-2,6-dimethyl-phenyl)-ethyl]-carbamic acid tert-butyl ester (290 mg; 0.40 mmol) in DMF (5mL) was added K2CO3 (262 mg; 1.9 mmol) and the resulting mixture was degassed with Argon for 5 min. At this time, Pd(OAc)2 (8.9 mg; 0.04 mmol) and 1,1-bis(diphenylphosphino) ferrocene (46 mg; 0.083 mmol) were added. Carbon monoxide was then bubbled through the resulting mixture for 10 min at rt, the reaction was capped, and warmed to 100°C for 6 h. After cooling to rt the mixture was partitioned between EtOAc and water, filtered through Celite, and then separated. The aqueous phase was then washed with a second portion of EtOAc. The aqueous phase was then acidified to pH 5 with 2N citric acid and the resulting aqueous solution extracted with EtOAc (4x). These latter EtOAc extracts were combined, dried over Na2SO4, filtered, and concentrated under reduced pressure to give the crude product (HPLC: 87% at 254 nm).
- E. 3-(2-{1-[[2-Amino-3-(4-carbamoyl-2,6-dimethyl-phenyl)-propionyl]-(3,4-dimethoxy-benzyl)-amino]-ethyl}-1H-imidazol-4-yl)-benzoic acid. 3-(2-{1-[[2-tert-Butoxycarbonylamino-3-(4-carbamoyl-2,6-dimethylphenyl)-propionyl]-(3,4-dimethoxy-benzyl)-amino]-ethyl}-1H-imidazol-4-yl)-benzoic acid may be BOC-deprotected using the procedure described in Example 1 for the conversion of Cpd 1e to Cpd 1f to give the title compound.
- A. [2-Benzyloxy-1-(2-oxo-2-phenyl-ethylcarbamoyl-ethyl]-carbamic acid tert butyl ester. The product was prepared using the procedure described in Example 1 and substituting N-α-BOC-L-serine benzyl ester for N-α-CBZ-L-alanine.
- B. [2-Benzyloxy-1-(4-phenyl-1H-imidazol-2-yl-ethyl]-carbamic acid tert butyl ester. By the procedure described in Example 1 for the conversion of Cpd 1a to Cpd 1 b, [2-benzyloxy-1-(2-oxo-2-phenyl-ethylcarbamoyl-ethyl]-carbamic acid tert butyl ester was converted to the product.
- C. [2-Benzyloxy-1-(4-phenyl-1H-imidazol-2-yl-ethylamine. [2-benzyloxy-1-(4-phenyl-1H-imidazol-2-yl-ethyl]-carbamic acid tert butyl ester may be BOC-deprotected using the procedure described in Example 1 for the conversion of Cpd 1e to Cpd 1f to give the product.
- D. [2-Benzyloxy-1-(4-phenyl-1H-imidazol-2-yl-ethyl]-isopropylamine. By the procedure described in Example 1 for the conversion of Cpd 1c to Cpd 1d, [2-benzyloxy-1-(4-phenyl-1H-imidazol-2-yl-ethylamine was converted to the product.
- E. [1-{[2-Benzyloxy-1-(4-phenyl-1H-imidazol-2-yl)-ethyl]-isopropylcarbamoyl}-2-(4-carbamoyl-2,6-dimethyl-phenyl)-ethyl]-carbamic acid tert-butyl ester. Using the procedure of Example 1 for the conversion of Cpd 1d to Cpd 1e, substituting [2-benzyloxy-1-(4-phenyl-1H-imidazol-2-yl-ethyl]-isopropylamine for Cpd 1d and substituting 2-tert-Butoxycarbonylamino-3-(4-carbamoyl-2,6-dimethyl-phenyl-propionic acid of Example 8 for 2-tert-butoxycarbonylamino-3-(4-hydroxy-2,6-dimethyl-phenyl)-propionic acid, the product was prepared.
- F. 4-(2-Amino-2-{[2-hydroxy-1-(4-phenyl-1H-imidazol-2-yl)-ethyl]-isopropyl-carbamoyl}-ethyl)-3,5-dimethyl-benzamide (TFA salt). A solution of [1-{[2-benzyloxy-1-(4-phenyl-1H-imidazol-2-yl)-ethyl]-isopropyl-carbamoyl}-2-(4-carbamoyl-2,6-dimethyl-phenyl)-ethyl]-carbamic acid tert-butyl ester, (0.287 g, 0.439 mmol), in chloroform (10 mL) was cooled in an ice bath and treated with 0.62 mL (4.4 mmol) of iodotrimethylsilane. The reaction, which immediately clouded, was warmed slowly to room temperature while stirring. After 16 h, the reaction was cooled in an ice bath to 5-10°C and treated with 100 mL of MeOH. The quenched mixture was stirred at 5-10°C for 30 min, removed from the ice bath and stirred for an additional 30 min, and concentrated in vacuo to obtain 0.488 g of orange residue that was subjected to reverse phase HPLC (water/ acetonitrile / 0.1 % TFA). The fractions of interest were combined and the sample was lyophilized to afford 0.150 g (59%) of 4-(2-amino-2-{[2-hydroxy-1-(4-phenyl-1H-imidazol-2-yl)-ethyl]-isopropylcarbamoyl}-ethyl)-3,5-dimethyl-benzamide (TFA salt) as a white powder (HPLC: 99% @ 254 nm and 100% @ 214 nm). MS (ES+) (relative intensity): 464.1 (100) (M+1).
- A. Trifluoromethanesulfonic acid 4-bromo-3,5-dimethyl-phenyl ester. To a cooled (0 °C) solution of 4-bromo-3,5-dimethylphenol (3.05 g, 15.2 mmol) in pyridine (8 mL) was added trifluoromethanesulfonic anhydride (5.0 g, 17.7 mmol) dropwise. After completion of addition, the resulting mixture was stirred at 0°C for 15 min, and then at rt overnight. The reaction was quenched by addition of water, and then extracted with EtOAc. The organic extracts were washed sequentially with water, 2N HCl (2x), brine, and then dried over MgSO4. Filtration and evaporation to dryness afforded Compound 15b (5.30 g, 95%) as a colorless oil. 1H NMR (300 MHz, CDCl3): δ 2.45 (6H, s), 7.00 (2H, s).
- B. 4-Bromo-3,5-dimethylbenzoic acid. To a solution of Compound 15b (6.57 g, 19.7 mmol) in DMF (65 mL) were added K2CO3 (13.1 g, 94.7 mmol), Pd(OAc)2 (0.44 g, 1.97 mmol) and 1,1'-bis(diphenylphosphino)ferrocene (2.29 g, 4.14 mmol). The resulting mixture was bubbled in gaseous CO for 10 min and was heated to 60°C for 7.5 h with a CO(g) balloon. The cooled mixture was partitioned between aqueous NaHCO3 and EtOAc, and filtered. The aqueous phase was separated, acidified with aqueous 6N HCl, extracted with EtOAc, and finally dried over Na2SO4. Filtration and concentration of the filtrate resulted in the crude Compound 15c as a brown residue, which was used in the next step without further purification.
- C. 4-Bromo-3,5-dimethyl-benzamide. A suspension of Compound 15c in DCM (40 mL) was added SOCl2 (3.1 mL, 42 mmol) and the mixture was heated at reflux for 2 h. Upon removal of the solvent by evaporation, the residue was dissolved in DCM (40 mL) and ammonium hydroxide (28% NH3 in water, 2.8 mL) was added. The mixture was heated at 50°C for 2 h and concentrated. The residue was diluted with H2O, extracted with EtOAc, and the organic portion was dried over Na2SO4. After filtration and evaporation, the residue was purified by flash column chramotagraphy (eluent: EtOAc) to give the Compound 15d (2.90 g, 65% for 2 steps) as an off-white solid. 1H NMR (300 MHz, CD3CN): δ 2.45 (6H, s), 5.94 (1 H, br s), 6.71 (1 H, br s), 7.57 (2H, s); MS(ES+)(relative intensity): 228.0 (100%) (M+1).
Method B: A mixture of Compound 15b (3.33 g, 10 mmol), PdCl2 (0.053 g, 0.3 mmol), hexamethyldisilazane (HMDS, 8.4 mL, 40 mmol), and dppp (0.12 g, 0.3 mmol) was bubbled with a gaseous CO for 5 min and then stirred in a CO balloon at 80°C for 4 h. To the reaction mixture was added MeOH (5 mL). The mixture was stirred for 10 min, diluted with 2N H2SO4 (200 mL), and then extracted with EtOAc. The EtOAc extract was washed with saturated aqueous NaHCO3, brine, and then dried over Na2SO4. Filtration and evaporation of the resultant filtrate gave a residue, which was purified by flash column chromatography (eluent: EtOAc) to give Compound 15d (1.60 g, 70%) as a white solid. - D. 2-tert-Butoxycarbonylaminoacrylic acid methyl ester. To a suspension of N-Boc-serine methyl ester (Cpd 15e, 2.19 g, 10 mmol) and EDC (2.01 g, 10.5 mmol) in DCM (70 mL) was added CuCl (1.04 g, 10.5 mmol). The reaction mixture was stirred at rt for 72 h. Upon removal of the solvent, the residue was diluted with EtOAc, washed sequentially with water and brine and then dried over MgSO4. The crude product was purified by flash column chromatography (eluent: EtOAc:hexane ∼1:4) to give Compound 15e (1.90 g, 94%) as a colorless oil. 1H NMR (300 MHz, CDCl3): δ 1.49 (9H, s), 3.83 (3H, s), 5.73 (1 H, d, J = 1.5 Hz), 6.16 (1 H, s), 7.02 (1 H, s).
- E. (Z)-2-tert-Butoxycarbonylamino-3-(4-carbamoyl-2,6-dimethylphenyl)acrylic acid methyl ester. A flask charged with Compound 15d (0.46 g, 2.0 mmol), Compound 15f (0.80 g, 4.0 mmol), tri-o-tolylphosphine (0.098 g, 0.32 mmol), DMF (8 mL) was purged with N2 (g) 3 times. After the addition of tris(dibenzylideneacetone)dipalladium (0) (0.074 g, 0.08 mmol) and TEA (0.31 mL, 2.2 mol), the reaction mixture was heated at 110°C for 24 h. At that time, the reaction was quenched by addition of water, and then extracted with EtOAc. The organic phase was washed with 1 N HCl, saturated aqueous NaHCO3, brine, and dried over MgSO4. The mixture was concentrated to a residue, which was purified by flash column chromatography (eluent: EtOAc:hexane∼1:1 to EtOAc only) to give Compound 15g (0.40 g, 57%) as a white solid. 1H NMR (300 MHz, CD3OD): δ 1.36 (9H, s), 2.26 (6H, s), 3.83 (3H, s), 7.10 (1 H, s), 7.56 (2H, s); 13C NMR (75 MHz, DMSO-d6): δ 17.6, 25.7, 50.2, 78.7, 124.9, 126.4, 128.3, 131.2, 135.2, 135.5, 152.8, 164.3, 169.6; MS (ES+) (relative intensity): 349.1 (38%)(M+1).
- F. (S)-2-tert-Butoxycarbonylamino-3-(4-carbamoyl-2,6-dimethylphenyl)propionic acid methyl ester. Into a reactor charged with a solution of Compound 15g (0.56 g, 1.6 mmol) in degassed MeOH (80 mL) was added [Rh(cod)(R,R-DIPAMP)]+BF4- under a stream of argon. The reactor was sealed and flushed with H2, stirred at 60 °C under 1000 psi of H2 for 14 d. The crude product was purified by flash column chromatography (eluent: EtOAc:hexane ∼1:1) to afford Compound 8c (0.54 g, 96%) as a white solid. ee: >99%; 1H NMR (300 MHz, CDCl3): δ 1.36 (9H, s), 2.39 (6H, s), 3.11 (2H, J = 7.2 Hz), 3.65 (3H, s), 4.53-4.56 (1 H, m), 5.12 (1 H, d, J = 8.7 Hz), 5.65 (1 H, br s), 6.09 (1H, br s), 7.46 (2H, s); MS(ES+) (relative intensity): 250.9 (100) (M-Boc)+.
- G. (S)-2-tert-Butoxycarbonylamino-3-(4-carbamoyl-2,6-dimethyl-phenyl)propionic acid. Into an ice-cooled solution of Compound 8c (0.22 g, 0.63 mmol) in THF (3.5 mL) was added an aqueous LiOH solution (1 N, 3.5 mL) and stirred at 0 °C. Upon completion of the reaction, the reaction was concentrated and the aqueous phase was neutralized with cooled aqueous 1 N HCl at 0 °C, and extracted with EtOAc. The combined extracts were dried over Na2SO4 overnight. Filtration and evaporation of the filtrate to dryness led to Compound 8d (0.20 g, 94%) as a white solid. 1H NMR (300 MHz, DMSO-d6): δ 1.30 (9H, s), 2.32 (6H, s), 2.95(1 H, dd, J = 8.8, 13.9 Hz), 3.10 (1 H, dd, J = 6.2, 14.0 Hz), 4.02-4.12 (1 H, m), 7.18-7.23 (2H, m), 7.48 (2H, s), 7.80 (1 H, s); MS(ES+) (relative intensity): 236.9 (6) (M-Boc)+.
- A. Racemic 2-tert-butoxycarbonylamino-3-(4-carbamoyl-2,6-dimethyl-phenyl)propionic acid methyl ester. To a reactor charged with a solution of Compound 15g (0.68 g, 1.95 mmol) in MeOH (80 mL) was added 10% Pd-C (0.5 g). The reactor was connected to a hydrogenator and shaken under 51 psi of H2 overnight. The mixture was filtered through a pad of Celite and the filtrate was concentrated to dryness to give Compound 16a (0.676 g, 99%) as a white solid. The 1H NMR spectrum was identical to that of (S)-2-tert-butoxycarbonylamino-3-(4-carbamoyl-2,6-dimethyl-phenyl)propionic acid methyl ester, Compound 8c.
- B. Racemic 2-tert-butoxycarbonylamino-3-(4-carbamoyl-2,6-dimethyl-phenyl)propionic acid. Using the procedure described for Example 15, for the preparation of (S)-2-tert-Butoxycarbonylamino-3-(4-carbamoyl-2,6-dimethyl-phenyl)propionic acid, racemic 2-tert-butoxycarbonylamino-3-(4-carbamoyl-2,6-dimethyl-phenyl)propionic acid, Compound 16b, was prepared.
Using the procedures of the Examples above and the appropriate reagents, starting materials and purification methods known to those skilled in the art, other compounds of the present disclosure may be prepared including but not limited to: