Heterogeneous asymmetric reactions: Part 28. Efficient and practical method for the preparation of ( R)- and ( S)-α-hydroxy esters by the enantioselective heterogeneous catalytic hydrogenation of α-ketoesters

Abstract

α-Ketoesters ( 1– 11: MeCOCOOR 1, R 1=Me, Et, i-Pr, i-Bu, t-Bu, neo-pentil, and RCOCOOEt, R= i-Pr, i-Bu, t-Bu, Ph, PhCH 2CH 2) can be hydrogenated with high enantioselectivity under mild experimental conditions (0 °C and room temperature, H 2 pressure 1–25 bar) on Pt-alumina catalyst modified with cinchona alkaloids. In this way α-hydroxy esters that are important building blocks in organic syntheses can be produced in high optical yield (>90%).