A Chemoselective and Scalable Transfer Hydrogenation of Aryl Imines by Rapid Continuous Flow Photoredox Catalysis

The chemoselective reduction of diaryl imines in the presence of competitively reducible groups is uniquely accessed through precise control of reaction and irradiation time by continuous flow visible light photoredox catalysis. The method enables the mild and efficient transfer hydrogenation of diaryl imines in the presence of sensitive functionality including halides, ester, ketone, and cyano groups. The flow protocol is efficient, rapid (>98% conversion within 9 min) and readily scaled to deliver multigram quantities of amine products in high purity.