Enantio- and chemoselective reduction of 2,4-diketo acid derivatives with cinchona modified Pt-catalyst—Synthesis of (R)-2-hydroxy-4-phenylbutyric acid ethyl ester

Abstract

The enantio- and chemoselective hydrogenation of several 2,4-diketo acid derivatives to the corresponding 2-hydroxy compounds with cinchona modified Pt catalysts can be carried out with chemoselectivities of >99% and enantioselectivities up to 86% (R) and 68% (S), respectively, and enrichment to >98% ee was possible for several compounds by one crystallization, opening up an efficient technical synthesis of (R)-2-hydroxy-4-phenylbutyric acid ethyl ester, a building block for several ACE inhibitors.