Ruthenium-catalysed asymmetric transfer hydrogenation of N-( tert-butanesulfinyl)imines

Abstract

The ruthenium complex prepared from [RuCl 2( p-cymene)] 2 and (1 S,2 R)-1-amino-2-indanol is a very efficient catalyst for the asymmetric transfer hydrogenation of ( R)- N-( tert-butanesulfinyl)ketimines in isopropanol. By carefully removing all possible moisture from the reaction medium, chiral primary amines with very high optical purities (up to >99% ee) can be easily prepared in excellent yields by the diastereoselective reduction of the imines followed by removal of the sulfinyl group under mild acidic conditions. Reaction times of 1–4 h were needed to complete the reduction reactions when they were performed at 40 °C.