Photoswitchable Regiodivergent Azidation of Olefins with Sulfonium Iodate(I) Reagent.

Photoswitchable strategy for selective azidation of structurally diverse olefins under transition-metal-free conditions is reported. The unprecedented reactivity of trimethylsulfonium [bis(azido)iodate(I)] species under visible light allows radical azidooxygenation of the C═C π bond with distinctive selectivity. In the absence of visible light, the reaction proceeds through an ionic intermediate which led to complementary regioselectivity to provide α-alkyl azides. Mechanistic studies reveal that light-controlled regiodivergent azidation involving radical or an ionic pathway can be accomplished with exclusive regioselectivity.