Novel catalysts for asymmetric reduction of carbonyl groups

The use of (i) enantiomerically pure phosphinamides coupled to borane and ( ii) an enantiomerically pure amino alcohol coupled to a transfer hydrogenat ion process, in the asymmetric catalysis of the reduction of ketones to alc ohols, is described. The former process is particularly suited to the reduc tion of alpha-chlorinated substrates, affording e.e.s of up to 94%, whilst the latter process is optimal for unfunctionalised ketones, affording e.e.s of up to 98%. (C) 1999 Elsevier Science B.V. All rights reserved.