Tetracyclic triterpenoids and terpenylated coumarins from the bark of Ailanthus altissima (“Tree of Heaven”)

► Five triterpenoids and one coumarin were isolated from Ailanthus altissima. ► Triterpenoid 1 has a rare oxetane ring in the C-17 side-chain. ► Compounds 4 and 5 are two unprecedented triterpenoid dimers. ► The cytotoxicities of the isolates against human cancer cells were evaluated.