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.