Chemoselective and Enantioselective Hydrogenation of 2,4‐Diaryl‐3H‐benzo[b]azepines Catalyzed by Dendritic Phosphinooxazoline Iridium Complexes

Abstract

An asymmetric hydrogenation of 2,4‐diaryl‐3H‐benzo[b]azepines, catalyzed by dendritic phosphinooxazoline (PHOX) iridium complexes, has been developed. Only the imine group was reduced, while the C=C bond remained untouched, affording a range of chiral 2,3‐dihydro‐1H‐benzo[b]azepine derivatives with good to excellent enantioselectivity (up to 91 % ee). A slightly positive dendritic effect on catalytic reactivity (up to 10 000 TON) was observed.

Recent Advances in the Enantioselective Synthesis of Chiral Amines via Transition Metal-Catalyzed Asymmetric Hydrogenation

“… For both catalytic systems, the corresponding optically active dihydrobenzodiazepines were obtained with good to excellent diastereoselectivity and excellent enantioselectivity. The same group reported other catalysts, including dendritic phosphinooxazoline iridium complexes, which proved highly efficient for both the partial and total AH of benzodiazepines. − …”

A diversity of recently reported methodology for asymmetric imine reduction

“…A facile and efficient approach to the hydrogenation of 2,4diaryl-3H-benzo [b]azepines has been developed by Fan and coworkers. 21 Dendritic phosphinooxazoline iridium complexes have been applied to synthesise optically active 2,4-diaryl-2,3dihydro-1H-benzo [b]azepine derivatives (Fig. 18).…”