An efficient and practical heterogeneous bimetallic Pd-Cu/C catalyst was identified as an alternative to Raney nickel for the highly diastereoselective hydrogenation of imines prepared from prochiral ketones and alpha-phenylethylamines. Chiral amines were obtained with diastereomeric excess (de) up to 94% using Pd-Cu/C, while conventional Pd-C catalysts afforded only 72% de. Optimization showed that a robust process required a palladium/copper ratio of 4:1. Evidence for the influence of catalyst pretreatment which may change the structure of the catalyst and/or metal oxidation states on the selectivity of the reaction is discussed. The bimetallic catalyst system provided consistent results on scale and performed reliably on a variety of substrates.
Diastereoselective synthesis of chiral secondary amines with two chiral centers directly attached to the nitrogen atom
作者:M. B. Eleveld、H. Hogeveen、E. P. Schudde
DOI:10.1021/jo00369a016
日期:1986.9
ELEVELD M. B.; HOGEVEEN H.; SCHUDDE E. P., J. ORG. CHEM., 51,(1986) N 19, 3635-3642