Enantioselective Hydrogenation of Olefins with Iridium-Phosphanodihydrooxazole Catalysts.

High turnover numbers and up to 98% ee were obtained in the catalytic hydrogenation of unfunctionalized aryl-substituted olefins with iridium-phosphanyldihydrooxazole complexes 1 (see reaction scheme). The anion of the complex-for example, hexafluorophosphate or tetrakis[3,5-bis(trifluoromethyl)phenyl]borate (BARF- )-has a remarkable effect on the reactivity and longevity of the catalyst.