Patent EP-0210896-B1 (EP)
Title: Optically pure derivates of 4-amino-3-hydroxycarboxylic acids and process for stereospecific synthesis
IPC: C07D207/38
Filed: 1986-07-03
Granted: 1990-10-10
Abstract: 1. Process for the stereospecific preparation of optically pure (3R, 4R)-4-amino-3-hydroxycarboxylic or (3S, 4S)-4-amino-3-hydroxycarboxylic acid derivatives of the formula :   see diagramm : EP0210896,P38,F1   in which : - W is hydrogen or an N-protecting group ; - R1 represents a linear or branched alkyl radical having from 1 to 6 carbon atoms, a methoxy-lower alkyl radical, a benzyloxy-lower alkyl radical, a methylthio-lower alkyl radical, a phenylthio-lower alkyl radical, a benzylthio-lower alkyl radical, an amino-lower alkyl radical which is free or substituted by a protecting group on the amine group, a (lower alkyl)amino-lower alkyl radical, a (lower dialkyl)amino-lower alkyl radical, a hydroxy-lower alkyl radical, a free or esterified carboxy-lower alkyl radical, a free or alkylated carboxamido-lower alkyl radical, a lower alkyl radical substituted at the same time and on the same carbon atom by an amine and a free or esterified carboxyl, a linear or branched alkenyl radical having from 2 to 6 carbon atoms, a methoxy-lower alkenyl radical such as methoxyvinyl, a phenoxy-lower alkeny radical, a benzyloxyalkenyl radical, a methylthio-lower alkenyl radical, a phenylthio-lower alkenyl radical, a benzylthio-lower alkenyl radical, an amino-lower alkenyl radical which is free or protected on the amine group, a (lower alkyl)amino-lower alkenyl radical, a (lower dialkyl)amino-lower alkenyl radical, a free or esterified carboxyalkenyl radical, a free or alkylated carboxamido-lower alkenyl radical or a linear or branched alkynyl radical having from 2 to 6 carbon atoms, or alternatively one of the radicals of the formulae : Cy-A-, Cy-O-A'- or R3 S-A'- in which : - Cy represents an aromatic or alicyclic hydrocarbon radical or a heterocyclic radical containing an oxygen or sulfur atom or one or two nitrogen atoms, Cy optionally being mono-, di- or tri-substituted by hydroxyl, lower alkyl, lower alkoxy, trifluoromethyl, nitro or halogeno radicals, - A represents a single bond or a linear or branched alkylene radical having from 1 to 5 carbon atoms, - A' represents a linear or branched alkylene radical having from 1 to 5 carbon atoms, and - R3 represents an S-protecting group ; and - R2 represents hydrogen, an alkali metal or alkaline earth metal, a lower alkyl or a benzyl which is unsubstituted or substituted by a lower alkyl group, a halogen or a nitro group, characterized in that it consists in : (a) reacting Meldrum's acid with a protected, optically pure amino acid, in the D or respectively L configuration, of the formula :   see diagramm : EP0210896,P38,F2   in which W' represents an N-protecting group such as Boc or Z, and R1 has the meaning indicated above, in a basic medium, in the presence of an activator for the amino acid (II) or of a coupling agent, (b) then heating the resulting compound of the formula (III) :   see diagramm : EP0210896,P39,F1   in which W' and R1 are as defined above, in a solvent at a temperature of between 30 degrees C and 100 degrees C, (c) then reducing the compound (IV-IVa) thus obtained in 2 tautomeric forms in equilibrium, in which the chirality of the carbon atom carrying the substituent R1 is preserved, the said compound being represented by the following structures :   see diagramm : EP0210896,P39,F2     see diagramm : EP0210896,P39,F3   in which W' and R1 are as defined above, with a metal borohydride in an acid medium, or by catalytic reduction under hydrogen pressure when R1 is not sensitive to hydrogenation (d) opening the ring of the resulting compound V of the formula :   see diagramm : EP0210896,P39,F4   in which W' and R1 are as defined above, either in an acid medium in the case where W' represents an N-protecting group which is stable in an acid medium, or in a basic medium in the case where W' represents a sterically hindered N-protecting group which is labile in an acid medium, and if necessary, finally deprotecting the nitrogen by removing the N-protecting group from the resulting compound of the formula :   see diagramm : EP0210896,P39,F5   by known methods.