Photochemical Formal [4 + 2] Cycloaddition of α-Bromo Phenylsulfones and Acetophenones with Alkenes

Benzocycles are the predominant skeletons in medicinal chemistry. Herein, we report a modular and practical [4 + 2] cycloaddition reaction for the photochemical synthesis of benzocyclic sulfones/ketones via sequential alkylation and arylation across an olefinic double bond. This scalable approach is compatible with the direct cyclization of α-bromo phenylsulfones or acetophenones with various alkenes, which can be expected to rapidly convert abundant alkene feedstocks into medically relevant molecules and the late-stage functionalization of pharmacologically related substrates.