Sarcanolides A and B: two sesquiterpenoid dimers with a nonacyclic scaffold from Sarcandra hainanensis

Two novel lindenane-type sesquiterpenoid dimers, sarcanolides A (1) and B (2), were isolated from the whole plants of Sarcandra hainanensis. These compounds feature a new nonacyclic scaffold in which the bond formation of C-11–C-7′ imposed the five-membered lactone ring in a full β-direction. Their structures, including the absolute configuration, were determined by NMR analysis, CD exciton chirality method, and ECD calculation.