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

Abstract
A mild, operationally convenient, and practical method for the synthesis of synthetically useful N-arylsulfonylimines from N-(arylsulfonyl)benzylamines using K2S2O8 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 K2S2O8 is reported to be problematic, the oxidation of N-(arylsulfonyl)benzylamines to N-arylsulfonylimines using K2S2O8 has been achieved for the first time. The dual role of the sulfate radical anion (SO4·−), including hydrogen atom abstraction (HAT) and single electron transfer (SET), is proposed to be involved in the plausible reaction mechanism.

Beilstein J. Org. Chem. 2023, 19, 771–777. doi:10.3762/bjoc.19.57

Source: Beilstein Journal of Organic Chemistry - June 5, 2023 Category: Chemistry Authors: Beilstein Journal of Organic Chemistry - Syndicated Feeds Tags: arylsulfonylimine benzylic oxidation benzyl sulfonamide K2S2O8 sulfate radical anion Full Research Paper Source Type: research