From Simple to Complex: Rhodium(III)-Catalyzed C-C Bond Cleavage and C-H Bond Functionalization for the Synthesis of 3a,8b-Dihydro-1H-cyclopenta[b]benzofuran-1-ones.

A rhodium(III)-catalyzed strategy for the one-step synthesis of polysubstituted cis-3a,8b-dihydro-1H-cyclopenta[b]benzofuran-1-ones from simple 2'-hydroxychalcones and alkynes is developed. This novel transformation involves a sequential C-C bond cleavage and dehydrogenative annulation, leading to the product bearing a quaternary and a tertiary carbon center. 13C labeling experiments revealed that C-C bond cleavage takes place not only at the C-C(C═O) bond but also at the C≡C bond. This study provides an alternative strategy using C-C bond cleavage thus demonstrating the power of this strategy combined with C-H bond functionalization for assembling complex structures from simple starting materials.