Zinc chloride induced stereoselection in syntheses of α-amino-β-hydroxy acid derivatives

Abstract

Schiff bases formed from condensation of glycine esters with diphenylmethyleneamine have been silylated followed by condensation with aliphatic and aromatic aldehydes at room temperature in the presence of catalytic amounts of ZnCl₂; the syn-condensation products are obtained in good yield and stereoselectivity, especially for aromatic aldehydes, and the sense of Stereoselection reverses in the presence of stoichiometric or excess of ZnCl₂.