Achiral β-amino alcohols as efficient ligands for the ruthenium-catalysed asymmetric transfer hydrogenation of sulfinylimines

Abstract

Some achiral β-amino alcohols have been shown as efficient ligands for the ruthenium-catalysed asymmetric transfer hydrogenation of N-( tert-butylsulfinyl)imines in isopropanol. The ruthenium complex prepared from [RuCl 2( p-cymene)] 2 (2.5 mol %) and 2-amino-2-methyl-1-propanol (5 mol %) leads to α-branched chiral primary amines with very high optical purities (up to 98% ee) by the diastereoselective reduction of the imines followed by removal of the sulfinyl group under mild acidic conditions. Short reaction times (2–3 h) were needed to complete the reduction reactions when they were performed at 50 °C.