Sulfate radical anion-induced benzylic oxidation of N -(arylsulfonyl)benzylamines to N -arylsulfonylimines.

A mild, operationally convenient, and practical method for the synthesis of synthetically useful N -arylsulfonylimines from N -(arylsulfonyl)benzylamines using K 2 S 2 O 8 in the presence of pyridine as a base is reported herein. In addition, a "one-pot" tandem synthesis of pharmaceutically relevant N -heterocycles by the reaction of N -arylsulfonylimines, generated in situ with ortho -substituted anilines is also reported. The key features of the protocol include the use of a green oxidant, a short reaction time (30 min), chromatography-free isolation, scalability, and economical, delivering N -arylsulfonylimines in excellent yields of up to 96%. While the oxidation of N -aryl(benzyl)amines to N -arylimines using K 2 S 2 O 8 is reported to be problematic, the oxidation of N -(arylsulfonyl)benzylamines to N -arylsulfonylimines using K 2 S 2 O 8 has been achieved for the first time. The dual role of the sulfate radical anion (SO 4 ·- ), including hydrogen atom abstraction (HAT) and single electron transfer (SET), is proposed to be involved in the plausible reaction mechanism.