Photocatalytic Strategy to Realize N-Debenzylation via Aerobic Oxidation Catalyzed by 4CzIPN

Abstract

It is a great challenge to remove the N-benzyl protecting group selectively by photocatalytic aerobic oxidation because amides or imines are easily formed from the oxidation of Nbenzylamine. In this study, a visible-light-induced debenzylation in yields of up to 88% was realized with a low catalytic loading of an organophotocatalyst [2 mol % 1,2,3,5-tetrakis(carbazol-9-yl)-4,6dicyanobenzene (4CzIPN)] in the presence of air and HCl under mild conditions. Mechanisms involving two-electron-transfer processes, a proton-transfer process, and a hydrolysis process were proposed based on the experimental studies and density functional theory (DFT) calculations. Acetone plays an important role in the proton-transfer process to promote these debenzylations.