An asymmetric reductive aldol-type reaction of α,β-unsaturated esters with carbonyl compounds using Rh catalyst and Et2Zn was investigated. A chiral zinc complex from α,β-unsaturated ester was easily generated as the key intermediate from Et2Zn and Wilkinson's catalyst with diisopropyl L-(+)-tartrate to give a variety of enantioenriched β-hydroxy esters. The reaction was also applied to the intramolecular
The reaction of RhCl(PPh3)(3) with Et2Zn easily generated a rhodium-hydride complex (Rh-H) that added to alpha,beta-unsaturated esters to form rhodium enolate complexes by formal 1,4-reduction. These rhodium enolates gave the corresponding Reformatslcy-type reagents through transmetalation, and they reacted with various aldehydes and ketones to give reductive aldol-type products in good to excellent yields. (C) 2013 Elsevier Ltd. All rights reserved.