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

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