Fine-Tuning of Modular Amino Alcohol Ligands for the Enantioselective Transfer Hydrogenation of Ketones

Abstract

A family of stereodefined, modular amino alcohols (3-alkoxy-1-amino-1-phenyl-2-propanols), in which the steric bulk of the alkoxy and amino substituents varies smoothly, has been synthesized from enantiomerically pure phenylglycidol, prepared by Sharpless epoxidation. These amino alcohols have been evaluated as ligands in the catalyzed [(amino alcohol)(arene)RuII] transfer hydrogenation of alkyl aryl ketones, with 2-propanol as the hydrogen source. Both the nitrogen substituent and the alkoxy group have been optimized for maximal enantioselectivity and catalytic activity in the process under consideration. (© Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)