Generation of Fused Seven-Membered Polycyclic Systems via Ring Expansion and Application to the Total Synthesis of Sesquiterpenoids

Seven-membered polycyclic architectures, widely present in natural products and molecular drugs, are challenging synthetic targets. However, methods for synthesizing fused medium-sized bicyclo[m.n.0] ring systems, including the benzocycloheptane systems, are still urgent. Herein we describe a base-induced ring expansion as a general strategy to construct a wide range of fused seven-membered ring systems. The application of this method was demonstrated by the efficient total syntheses of two sesquiterpenoids, plecarpenene and plecarpenone, both bearing a fused bicyclo[5.3.0]decane skeleton.

Automated summary

Seven-membered polycyclic architectures, commonly found in natural products and molecular drugs, are challenging targets in synthesis. This study presents a base-induced ring expansion as a general strategy for constructing a wide range of fused seven-membered ring systems. The successful synthesis of two sesquiterpenoids, plecarpenene and plecarpenone, demonstrates the efficacy of this method for constructing fused bicyclo[5.3.0]decane skeletons.