title: A novel conversion of C(19)-diterpenoid alkaloids into aconane-type diterpenes with eight-membered ring system via skeletal rearrangement of corresponding diazonium derivatives.
abstract: A new and efficient approach toward the conversion of C(19)-diterpenoid alkaloids into diterpenes with [6+8+5+6] ring system is reported. Treatment of imines 5, 14, and 24 derived from the C(19)-diterpenoid alkaloids with NaNO(2)-NaOAc-HOAc afforded a series of novel rearrangement diterpenes 6-8, 15-19, and 25-27, respectively. The lactone 11 was obtained in 41% yield by treating 5 with NaNO(2)-HBr-Br(2). The formation of diazonium intermediate is postulated, which was subsequently subjected to skeletal rearrangement, leading to the enlargement of B ring. All the new compounds were isolated and fully characterized.
authors.affiliation: Department of Chemistry of Medicinal Natural Products, West College of Pharmacy, Sichuan University, Chengdu 610041, China.
authors.forename: Hong
authors.initials: H
authors.lastname: Ji
authors.forename: Qiao-Hong
authors.initials: QH
authors.lastname: Chen
authors.forename: Feng-Peng
authors.initials: FP
authors.lastname: Wang
mesh_terms: D000470:Alkaloids / Q000737:chemistry*; D002384:Catalysis; D003979:Diazonium Compounds / Q000737:chemistry*; D004224:Diterpenes / Q000138:chemical synthesis / Q000737:chemistry*; D007097:Imines / Q000737:chemistry
chemical_list: D000470:Alkaloids; D003979:Diazonium Compounds; D004224:Diterpenes; D007097:Imines