Photoinduced Cross-coupling of Indoles with ICF2SO2 Ph Promoted by DABSO

Abstract

DABSO, typically a solid surrogate of SO₂, enables the efficient synthesis of sulfonyl compounds, such as sulfonamides and sulfones. Here, DABSO was identified as an effective electron donor compound in the coupling reaction of indoles with ICF₂SO₂Ph. Under blue light irradiation in methanol or a mixed solvent of methanol and dichloromethane, DABSO promotes (phenylsulfonyl)difluoromethylation at the C2-H bond of indole, delivering the corresponding products in up to 93% yield.Compared with existing methods, this approach exhibits significantly enhanced reactivity and superior chemoselectivity. In contrast, in methanol, the C3-H bond preferentially affords the corresponding methyl ester. Switching to acetonitrile as the solvent allows selective introduction of a phenylthiol group at the C3-H position, yielding the products in moderate amounts.Overall, this DABSO-based reaction strategy enables diverse, site-selective transformations under tunable conditions.