Enantioselective synthesis of cis -hexahydro- γ -carboline derivatives via Ir-catalyzed asymmetric hydrogenation.

A novel synthetic route was developed for the construction of a chiral cis -hexahydro-γ-carboline derivative through Ir/ZhaoPhos-catalyzed asymmetric hydrogenation of corresponding tetrahydro-γ-carboline with high yields (up to 99% yield), excellent diastereoselectivities (up to >99 : 1 dr) and enantioselectivities (up to 99% ee), and high substrate-to-catalyst ratios (up to 5000).