Chiral terpene auxiliaries.: Part 1:: Highly enantioselective reduction of ketones with borane catalyzed by an oxazaborolidine derived from (-)-β-pinene

(1R,2S,3R,5R)-3-Amino-6,6-dimethyl-2-hydroxybicyclo[3.1.1]heptane was synthesized in three steps from (-)-beta-pinene. It was used for the in situ generation of a B-methoxy-oxazaborolidine catalyst for the asymmetric reduction of alkyl-aryl ketones with borane-dimethyl sulfide complex. In the presence of 3 mol % of the catalyst, the product alcohols were obtained in high yields and with enantiomeric excesses in the range of 93-98%. (c) 2005 Elsevier Ltd. All rights reserved.