title: Total Syntheses of Sesterterpenoid Ansellones A and B, and Phorbadione.
abstract: Ansellane-type sesterterpenoids including, ansellones A-G and (+)-phorbadione are structurally novel marine secondary metabolites which exhibit anticancer and anti-HIV activity. The first, asymmetric total syntheses of three structurally representative members, (-)-ansellones A and B and (+)-phorbadione, were accomplished in 16-23 steps from (+)-sclareolide. The route features the first regioselective cyclization of vinyl epoxides with internal alcohol nucleophiles in a 1,4-addition manner (SN2'). Additionally, the allylic C-H oxidation was exploited at a late stage of the synthesis of (-)-ansellone A and (+)-phorbadione. This strategy is expected to be applicable to the synthesis of other ansellane sesterterpenoids.
authors.affiliation: Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, HK, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Zhang
authors.affiliation: Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, HK, China.
authors.forename: Hongliang
authors.initials: H
authors.lastname: Yao
authors.affiliation: Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, HK, China.
authors.forename: Jingxun
authors.initials: J
authors.lastname: Yu
authors.affiliation: Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, HK, China.
authors.forename: Zhihong
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, HK, China.
authors.forename: Rongbiao
authors.identifier: 0000-0002-2740-5222
authors.initials: R
authors.lastname: Tong
mesh_terms: D019380:Anti-HIV Agents / Q000138:chemical synthesis* / Q000737:chemistry; D000970:Antineoplastic Agents / Q000138:chemical synthesis* / Q000737:chemistry; D003500:Cyclization; D004224:Diterpenes / Q000138:chemical synthesis / Q000737:chemistry; D004852:Epoxy Compounds / Q000138:chemical synthesis / Q000737:chemistry; D008958:Models, Molecular; D054830:Sesterterpenes / Q000138:chemical synthesis* / Q000737:chemistry; D013237:Stereoisomerism
chemical_list: D019380:Anti-HIV Agents; D000970:Antineoplastic Agents; D004224:Diterpenes; D004852:Epoxy Compounds; D054830:Sesterterpenes; C109395:sclareolide
keywords: cyclizations; natural products; structure determination; terpenoids; total synthesis