Electrochemistry-Driven Strain Release of Bicyclo[1.1.0]Butanes for the Synthesis of Cyclobutenes

Cyclobutenes serve as highly valuable synthetic targets in organic chemistry. However, the efficient construction of the cyclobutene scaffold has long posed a significant challenge, particularly in the synthesis of sulfonyl-substituted cyclobutenes, which remain difficult to access via conventional methods, including transition-metal catalysis, organocatalysis, and photocatalysis. In this work, we developed an electrochemistry-driven strain-release strategy for bicyclo[1.1.0]butanes functionalization by using selenium sulfonates. This unique transformation proceeds via a radical addition/tandem oxidation-elimination process, enabling the synthesis of diverse cyclobutenes under transition metal-free and chemical oxidant-free conditions. Importantly, bifunctional addition products are also achievable under inert atmosphere, which can be further transformed into the corresponding cyclobutenes under given electrochemical conditions. Mechanistic investigations and theoretical density functional theory calculations suggest the involvement of radical intermediates, providing insight into the chemical selectivity of the reaction.