Iridium-Catalyzed Asymmetric Hydrogenation of Sterically Hindered Cyclic Imines for Enantioselective Synthesis of Tetrahydroisoquinolines.

An efficient enantioselective hydrogenation of sterically hindered cyclic imines catalyzed by the Ir-tBu-ax-Josiphos complex has been described, producing a series of useful chiral bulky tetrahydroisoquinoline analogs in high isolated yields (85-96%) with good to excellent enantioselectivities (74-99% ee). This transformation provided highly straightforward access to the useful derivatives of tetrahydroisoquinolines, which are of great potential value in drug molecule and natural product research.