Visible-light-initiated regioselective sulfonylation/cyclization of 1,6-enynes under photocatalyst- and additive-free conditions†
Without employing any photocatalyst and additive, an economical, eco-friendly and practical strategy has been developed for the visible-light-initiated regioselective sulfonylation/cyclization of 1,6-enynes in a biomass-derived green solvent 2-methylTHF from easily accessible sulfonyl chlorides under open-air conditions at room temperature. Compared with conventional heating conditions, the use of a 3 W blue light-emitting diode (LED) or sunlight not only reduces energy consumption but also minimizes side reactions. This transformation has excellent regioselectivity, mild reaction conditions, broad substrate scope and ease of scale-up. Moreover, mechanistic studies indicated that a sulfonyl radical pathway was involved in this reaction.