Room-Temperature C-C Bond Cleavage and Ring Expansion of Benzene by a Copper(I)-Substituted Silylene.

The cleavage and functionalization of benzene C-C bonds under mild conditions is of fundamental interest yet remains challenging. Herein, we report that an in situ generated copper(I)-substituted silylene undergoes reversible insertion into benzene at room temperature, affording a silepin with a reactive Cu-Si bond. This metal-silicon linkage enables diverse substitutions (H, halogen, alkyl, allyl, allenyl, propargyl) through facile cleavage, offering a mild strategy for benzene ring expansion and functionalization.