Enantioselective Hydrogenation of Aromatic N-Aryl Imines

Significance

The reported {Ir[(S,S)-t-Bu-BisP*]}[BARF] catalyst 2 was shown to hydrogenate N-aryl imines with good to excellent enantioselectivity. The catalyst led to higher selectivity for electron-deficient systems (R¹ or R², 84-99% ee) and to lower selectivity for electron-rich systems (R¹ or R², 69-86% ee). The method is complementary to the [Ir(ddppm)(cod)]PF₆ system, where electron-rich aryl groups showed better selectivity (A. Dervisi et al. Adv. Synth. Catal. 2006, 175-183). Also, the method provides an alternative to the phosphanylsulfoximine/[Ir(cod)Cl]₂ system (C. Moessner, C. Bolm Angew. Chem. Int. Ed. 2005, 44, 7564-7567).