title: Enantioselective total synthesis and structural assignment of callyspongiolide.
abstract: We have elucidated the complete absolute configuration of callyspongiolide and unambiguously assigned its stereochemistry at the C-21 center through synthesis. Four stereoisomers of callyspongiolide were synthesized in a convergent and enantioselective manner. A late-stage Sonogashira coupling forges the diene-ynic side chain. Other notable reactions are Yonemitsu's variation of Yamaguchi macrolactonization to cyclize an alkynic seco acid, highly trans-selective Julia-Kocienski olefination, CBS reduction to set the C-21 stereocenter, and methyl cuprate addition to an unsaturated pyranone to install the C-5 methyl center.
authors.affiliation: Department of Chemistry and Department of Medicinal Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907, USA. akghosh@purdue.edu.
authors.forename: Arun K
authors.initials: AK
authors.lastname: Ghosh
authors.affiliation: Department of Chemistry and Department of Medicinal Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907, USA. akghosh@purdue.edu.
authors.forename: Luke A
authors.initials: LA
authors.lastname: Kassekert
authors.affiliation: Department of Chemistry and Department of Medicinal Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907, USA. akghosh@purdue.edu.
authors.forename: Joseph D
authors.initials: JD
authors.lastname: Bungard
mesh_terms: D018942:Macrolides / Q000138:chemical synthesis* / Q000737:chemistry*; D008968:Molecular Conformation; D015394:Molecular Structure; D013237:Stereoisomerism
chemical_list: D018942:Macrolides; C588104:callyspongiolide