Stereo- and chemoselective transfer hydrogenation of carbonyl groups with RuCl 2(PPh 3) 3 and BINAP-Ru as catalysts and Et 3NH +H 2PO 2−·1,5H 2O as a hydrogen donor

Abstract

Using Et 3NH +H 2PO 2 −.1.5 H 2O as a hydrogen donor, the RuCl 2(Ph 3P) 3, RuCl 2(PPh 3) 3 C and BINAP-Ru proved highly active catalysts for transfer hydrogenation of ketones under milder conditions than other hydrogen donors. 2-Methyl-, 2-chloro-, 2-(ethoxy-carbonyl)cyclohexanones and -cyclopentanones were reduced to the less stable axial alcohols in excellent diastereoisomeric excess (de: 90–100%), and the carbonyl group of α,β-unsaturated ketones was selectively reduced, in contrast with other hydrogen donors the CC bond was reduced.