Electrochemical Cascade Cyclization of Sulfoxonium Ylides with Unactivated Alkenes.

Herein, we report an electrochemical cascade cyclization of sulfoxonium ylides with unactivated alkenes under mild conditions. This protocol provides a concise and sustainable route to γ-substituted 1-tetralones. Mechanistically, this oxidant- and metal-free transformation proceeds via the generation of an α-carbonyl carbon radical through the reductive proton-coupled electron transfer of sulfoxonium ylides at the cathode, which subsequently triggers a radical addition/cascade cyclization sequence with unactivated alkenes. The success of this reaction relies on the precise matching of redox potentials to facilitate both the initiation of the reduction and the subsequent oxidation of the key radical intermediate to complete the cycle. This work not only provides a practical and complementary synthetic strategy for the construction of valuable tetralone scaffolds but also expands the reactivity landscape of sulfoxonium ylides in catalyst-free electrochemical radical chemistry.