Enantioselective Rh-catalyzed transfer hydrogenation of α-sulfonyloxy heteroaryl ketones; asymmetric synthesis of (S)-bufuralol

Asymmetric transfer hydrogenation of a-sulfonyloxy heteroaryl ketones mediated by Cp*RhCl[(S,S)-TsDPEN] using an azeotropic mixture of formic acid/triethylamine afforded the corresponding diol-2-monosulfonates in excellent yield with high enantioselectivity. This led to the asymmetric synthesis of (S)-bufuralol. (C) 2009 Elsevier Ltd. All rights reserved.