title: Asymmetric Total Syntheses of ent-Ascospiroketals A and B.
abstract: A new hypothetic biosynthesis of the tricyclic spiroketal core of ascospiroketals A and B is proposed, which guided the development of a novel synthetic strategy for the asymmetric total synthesis of ent-ascospiroketals A and B. The synthesis features an efficient ring contraction rearrangement of the 10-membered lactone to the tricyclic spiroketal cis-fused γ-lactone core, which served as the common intermediate for the synthesis of both ent-ascospiroketals A and B through the Stille coupling reaction at the final step. In addition, seven diastereomers were prepared to conclusively confirm the structure of ent-ascospiroketal B.
authors.affiliation: Department of Chemistry, The Hong Kong University of Science and Technology , Clearwater Bay, Kowloon, Hong Kong, China.
authors.forename: Jian
authors.initials: J
authors.lastname: Wang
authors.affiliation: Department of Chemistry, The Hong Kong University of Science and Technology , Clearwater Bay, Kowloon, Hong Kong, China.
authors.forename: Rongbiao
authors.initials: R
authors.lastname: Tong
mesh_terms: D004988:Ethers, Cyclic / Q000138:chemical synthesis* / Q000737:chemistry; D005663:Furans / Q000737:chemistry*; D007783:Lactones / Q000737:chemistry*; D015394:Molecular Structure; D013141:Spiro Compounds / Q000138:chemical synthesis* / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D004988:Ethers, Cyclic; D005663:Furans; D007783:Lactones; D013141:Spiro Compounds; C518010:ascospiroketal A; C518009:ascospiroketal B; C520774:spiroketal