Formal Carbene Insertion into C—C Bond: Rh(I)-Catalyzed Reaction of Benzocyclobutenols with Diazoesters.

A Rh(I)-catalyzed formal carbene insertion into C–C bond of benzocyclobutenols has been realized by employing diazoesters as carbene precursors. The product indanol derivatives were obtained in good yields and in diastereoselective manner under mild reaction conditions. All-carbon quaternary center is constructed at the carbenic carbon. This catalytic reaction involves selective cleavage of C–C bond, Rh(I) carbene insertion, and intramolecular aldol reaction.