Highly enantioselective access to α-dibenzylamino ketones from chiral nonracemic α-bromo α′-sulfinyl ketones by dynamic kinetic resolution: Synthesis of (2R,1′S)-2-[1-(dibenzylamino)alkyl]oxiranes

Abstract

A novel and efficient synthesis of enantiomerically pure α-dibenzylamino α′-sulfinyl ketones starting from a mixture of both epimers of α-bromo α′-(R)-sulfinyl ketone has been realized through combined in situ substitution-epimerization in a so-called Dynamic Kinetic Resolution (DKR). The scope of the reaction has been examined, and four differently substituted α-(S)-dibenzylamino α′-(R)- sulfinyl ketones were obtained in good yields with excellent diastereoselectivities. The utility of these derivatives was further illustrated with a highly stereoselective synthesis of syn-(2R,1′S)-2-(1- dibenzylaminoalkyl)oxiranes. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.