DIASTEREOSELECTIVE PROCESS FOR PREPARING N-SUBSTITUTED AMINO ACIDS AND DERIVATIVES

摘要

A process for preparing an (S, S) or (R, R) diastereoisomer of formula (X) or salts, esters or amides thereof, wherein R<3> and R<4> independently represent hydrogen, alkyl, aryl or aryl substituted with halogen, alkyl, nitro or alkoxy, and n and m independently represent integers from one to six, comprising combining a cyanide compound of the formula: M<1>C=N, wherein M<1> is hydrogen, trimethylsilyl or a metal, with an optional proton source, a solvent and a Lewis acid of the formula: M<2>X4, AlCl3 or BF3, wherein M<2> is Sn or Ti and X represents chloro, bromo, fluoro or iodo, with an alpha -amino acid compound or salts or esters thereof, followed by addition of an acyl or acetal compound to give the diastereoisomer of formula (X).