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.