N-Radical Initiated Aminosulfonylation of Unactivated C(sp3)-H Bond through Insertion of Sulfur Dioxide.

Abstract

N-Radical initiated aminosulfonylation of unactivated C(sp3)-H bond through insertion of sulfur dioxide in the presence of visible light is reported. O-Aryl oximes react with DABCO·(SO2)2 smoothly at room temperature under blue LED irradiation without any metals or photoredox catalysts, generating diverse 5,6-dihydro-4H-1,2-thiazine 1,1-dioxides in good yield. Additionally, this approach can be extended to the synthesis of 1H-benzo[d][1,2]thiazine 2,2-dioxides. During the reaction process, an N-radical is initiated by the treatment of O-aryl oximes with DABCO·(SO2)2 under visible-light irradiation. It is followed by aminosulfonylation of a nearby C(sp3)-H bond through 1,5-hydrogen atom transfer with accompanying insertion of sulfur dioxide to provide 1,2-thiazine 1,1-dioxide derivatives.