Catalytic enantioselective intermolecular reductive aldol reaction to ketones

We describe the first example of a catalytic criantioselective intermolecular reductive aldol reaction. Three types of reactions were studied: (1) reactions between acetophenone and methyl acrylate; (2) reactions between symmetric ketones and beta-substituted a,p-unsaturated esters; and. (3) reactions between acetophenone derivatives and an allenic ester. Although only moderate enantioselectivity was obtained in the first reaction type, high to excellent enantioselectivity was realized in the enantio-induction at the alpha-position in the, second reaction type and at the delta-position in the third reaction type. Specifically, the third reaction type afforded the corresponding tertiary alcohols with up to 99% ee. Pre-activation of the nucleophile by silyl enolate formation is not necessary in these one-pot catalytic enantioselective reductive aldol reactions. (c) 2005 Elsevier Ltd. All rights reserved.