Benzylic C(sp3)–H bond sulfonylation of 4-methylphenols with the insertion of sulfur dioxide under photocatalysis

Abstract

Sulfonylation of the benzylic C–H bond is developed through a three-component reaction of aryldiazonium tetrafluoroborates, 4-methylphenols and sodium metabisulfite (Na₂S₂O₅). The inorganic sulfite of sodium metabisulfite is used as the SO₂ surrogate. In this transformation, benzylic C(sp³)–H bond sulfonylation is achieved in the presence of a photocatalyst under visible light. A radical pathway involving the arylsulfonyl radical and intermolecular hydrogen atom abstraction is proposed.