Asymmetric synthesis of N-methyl-α-amino esters from a glyoxal derived chiral heterocycle

Abstract

The reaction between a chiral template derived from glyoxal with organometallic reagents leads ultimately to the optically active title compounds. The stereochemical outcome of the key-step which involves substitution of a thiophenol group depends on the organometallic: predominantly inversion with alkyl copper or complete retention with alkyl zinc halides. The stereodirecting effect of an allylic hydroxy group in an iminium intermediate is evidenced in the case of the organozinc reagent.