Journal of Catalysis, Vol.193, No.1, 161-164, 2000
First enantioselective hydrogenation of a trifluoro-beta-keloester with cinchona-modified platinum
A series of trifluoromethyl ketones possessing different functional groups were hydrogenated over Pt/Al2O3 modified by cinchonidine and O-methylcinchonidine. The highest enantiomeric epcess of 90% was achieved in the hydrogenation of ethyl 4,4,4-trifluoroacetoacetate. The remarkable variation of enantioselectivity in the synthesis of various alpha,alpha,alpha-trifluoromethyl alcohols is interpreted by electronic and steric effects. Future mechanistic studies have to clarify the unexpectedly big influence of acidic solvent and the special role of the (C9)-OH group in cinchonidine.