Asymmetric Hydrogenation of Imines Using NHC-Phosphine Iridium Complexes

alpha-Chiral amines represent a frequently observed functional group in pharmaceuticals. Here, the synthesis of such motifs (up to 91% ee) is described by asymmetric hydrogenation of imines catalyzed by NHC,P-iridium complexes. The hydrogenation proceeded smoothly, even under balloon pressure of hydrogen atmosphere. Mechanistic experiments indicated that the reduction most likely advances by a combination of direct hydrogenation and a hydrogen transfer process using either H-2 or iPrOH as the reductant, respectively.

Automated summary

This article describes a method for synthesizing highly enantioselective alpha-chiral amine compounds using NHC, P-iridium complexes catalyzed asymmetric hydrogenation of imines. The hydrogenation proceeds smoothly, even under hydrogen pressure. Experimental results indicate that the reduction process most likely progresses through a combination of direct hydrogenation and a hydrogen transfer process using either H-2 or iPrOH as the reductant, respectively.