N-benzyl-norephedrine derivatives as new, efficient ligands for ruthenium-catalyzed asymmetric transfer hydrogenation of functionalized ketones

Significant catalytic activities (up to 600 h(-1) at 20 degrees C) and enan tiomeric excesses ranging from 56 to 89% for the asymmetric transfer hydrog enation of beta-ketoesters, methoxyacetone and 2-acetylpyridine to the corr esponding alcohols are achieved in the presence of catalytic combinations o f [RuCl2(eta(6)-arene)](2) and N-substituted derivatives of(1S,2R)-norephed rine such as N-benzyl-norephedrine and N-(4-biphenyl)methyl-norephedrine. ( C) 1999 Elsevier Science Ltd. All rights reserved.