Phosphinomethyloxazolines as Efficient Ligands for the Iridium-Catalyzed Enantioselective Hydrogenation of Unfunctionalized Tetrasubstituted Olefins

Abstract

- Iridium-catalyzed enantioselective hydrogenation has become the method of choice for the enantioselective reduction of unfunctionalized olefins. In particular, tetrasubstituted olefins are interesting substrates, which allow the generation of two adjacent stereocenters in a single hydrogenation step. For this class of substrates, chiral phosphinomethyl-oxazolines have proved to be very efficient ligands. Herein we report a short and practical synthesis of differently substituted phosphinomethyl-oxazolines and the corresponding iridium(COD) complexes. The scope of these catalysts is demonstrated by hydrogenation studies of four tetrasubstituted olefins.