Aggreganoids A–F, Carbon-Bridged Sesquiterpenoid Dimers and Trimers from Lindera aggregata

Six oligomeric sesquiterpenoids, aggreganoids A–F (1–6), were isolated from Lindera aggregata. Aggreganoid A (1) and B (2) are two unprecedented methine- or methylene-bridged sesquiterpenoid trimers possessing a unique C₄₆ skeleton. Aggreganoids C–F (3–6) are the first examples of carbon-bridged disesquiterpenoids with a C₃₃ or C₃₁ skeleton in the plant kingdom. Their structures and absolute configurations were elucidated by using spectroscopic methods and electronic circular dichroism calculations. A plausible biosynthetic pathway of these compounds was also proposed.