Enantioselective hydrogenation of diaryl-substituted a,b-unsaturated nitriles

a,b-Unsaturated nitriles can be hydrogenated with enantioselectivities up to 88% ee using chiral rutheniumdiphenylphosphino bisaryl and bisheteroaryl complexes such as ruthenium(II)-BINAP and ruthenium(II)-BINP. Mechanistic investigations indicate that conversion is accelerated by electron-rich ligands and that an additional coordinative group needs be present in order to promote conversion. The chiral products are useful building blocks for the synthesis of histamine H2 agonists of the arpromidine type.