Enantioselective hydrogenation of aromatic ketones: structural effects

摘要

Enantioselective hydrogenation of acetophenone derivatives demonstrates the potential of the Pt-cinchona system in the synthesis of chiral alcohols that possess no functional group in the a-position to the CH-OH group. Electron-withdrawing functional groups in the aromatic ring increased the reaction rate and enantiomeric excess (ee), and the position of the group (o-, m-, or p-) was also important. 60% ee was obtained in the hydrogenation of 3,5-di(trifluoromethyl)acetophenone under ambient conditions, though the special role of reaction parameters has not been investigated yet. Addition of cinchonidine slowed down all hydrogenation reactions-an unprecedented behaviour for chirally modified Pt. (C) 2003 Elsevier Inc. All rights reserved. [References: 28]