Accessing Furan-2(5H)-one-Substituted Cyclic Ketones via Rh-Catalyzed Carbene/Alkyne Metathesis-Triggered Semipinacol Rearrangement.

In this work, we developed an efficient and practical method to construct diverse furan-2(5H)-one-substituted cyclic ketones. This strategy enables ring expansion via a carbene/alkyne metathesis-semipinacol rearrangement cascade, efficiently affording various functionalized products under mild conditions with a broad substrate scope. Moreover, a catalyst loading of only 0.1 mol % was sufficient to drive the reaction efficiently. Significantly, the method also allows for structural modifications of structurally complex natural products.