title: Studies towards simalikalactone D and quassimarin: construction of an advanced pentacyclic intermediate.
abstract: An advanced pentacyclic intermediate, amenable to further elaboration into the target molecules simalikalactone D and quassimarin, has been synthesized from (S)-(+)-carvone in 21 steps and with an overall yield of 12 %. The synthesis is efficient, stereocontrolled, enantiospecific, and chirality productive, creating eight new chiral centres in pentacycle, and should provide opportunities for rapid access to simalikalactone D analogues and other bioactive quassinoids. The reaction sequence involves a regioselective bishydroxylmethylation, a stereocontrolled epoxidation, an epoxymethano-bridge formation, a 1,3-sigmatropic rearrangement and an intramolecular Diels-Alder reaction as the key steps.
authors.affiliation: Department of Chemistry, The Chinese University of Hong Kong, Shatin, NT, Hong Kong (VR China). tony.shing@cuhk.edu.hk
authors.forename: Tony K M
authors.initials: TK
authors.lastname: Shing
authors.forename: Xue Y
authors.initials: XY
authors.lastname: Zhu
authors.forename: Yeung Y
authors.initials: YY
authors.lastname: Yeung
mesh_terms: D000970:Antineoplastic Agents / Q000138:chemical synthesis / Q000737:chemistry*; D018360:Crystallography, X-Ray; D006576:Heterocyclic Compounds, 4 or More Rings / Q000138:chemical synthesis / Q000737:chemistry; D015394:Molecular Structure; D036702:Quassins / Q000138:chemical synthesis* / Q000737:chemistry*
chemical_list: D000970:Antineoplastic Agents; D006576:Heterocyclic Compounds, 4 or More Rings; D036702:Quassins; C024970:simalikalactone D; C013234:quassimarin