Ir-SpinPHOX Catalyzed Enantioselective Hydrogenation of 3-Ylidenephthalides.

The first asymmetric hydrogenation of 3-ylidenephthalides has been developed using the IrI complex of a spiro[4,4]-1,6-nonadiene-based phosphine-oxazoline ligand (SpinPHOX) as the catalyst, affording a wide variety of chiral 3-substituted phthalides in excellent enantiomeric excesses (up to 98 % ee). The utility of the protocol has been demonstrated in the asymmetric synthesis of chiral drugs NBP and BZP precursor, as well as the natural products chuangxinol and typhaphthalide.