Intramolecular oxysulfonylation of alkenes with the insertion of sulfur dioxide under photocatalysis

Intramolecular oxysulfonylation of alkenes with the insertion of sulfur dioxide promoted by visible light is developed. The combination of 4-substituted pent-4-en-1-ols, DABCO·(SO2)2, and aryldiazonium tetrafluoroborates under mild conditions in the presence of a photocatalyst provides sulfonated 2,2-disubstituted tetrahydrofurans in moderate to good yields. Moreover, this protocol can be further extended to 5-phenylhex-5-en-1-ol and [2-(prop-1-en-2-yl)phenyl]methanol for the construction of sulfonyl-containing tetrahydropyran and 1,3-dihydroisobenzofuran derivatives. Preliminary mechanistic studies show that the arylsulfonyl radical is the key intermediate in the reaction process.