Visible light-induced cascade sulfonylation/annulation of ortho-allyloxy chalcones with sodium sulfinates for the synthesis of sulfonated chromane derivatives

A visible-light-induced radical cascade reaction for the synthesis of structurally diverse sulfonated chromanes is described. The protocol involves the addition of sulfonyl radicals to ortho-allyloxy chalcones and intramolecular Michael addition reactions in the presence of eosin Y as a photocatalyst. Additionally, this protocol shows that it is also an effective method to construct seven-membered oxygen-containing heterocycles. The method features a wide substrate scope, the use of easily accessible materials and excellent functional group tolerance with high to excellent yields. Control experiments and mechanistic studies indicate that a visible light-induced radical cascade process is involved in the transformation.