title: Total synthesis of spirotenuipesines A and B.
abstract: Spirotenuipesines A and B, isolated from the entomopathogenic fungus Paecilomyces tenuipes by Oshima and co-workers, have been synthesized. The synthesis features the highly stereoselective construction of two vicinal all-carbon quaternary centers (C(5) and C(6)) via an intramolecular cyclopropanation/radical initiated fragmentation sequence and a diastereoselective intermolecular Diels-Alder reaction between alpha-methylenelactone dienophile 20 and synergistic diene 6a. Installation of the C(9) tertiary alcohol occurred via nucleophilic methylation. An RCM reaction to produce a tetrasubstituted double bond in the presence of free allylic alcohol and homoallylic oxygenated functional group is also described. This route shortened the synthesis of 11 from 9 steps to 3 steps. We have further developed a strategy to gain access to optically active spirotenuipesines A and B through the synthesis of enantioenriched 10 from commercially available R-(-)-epichlorohydrin.
authors.affiliation: Department of Chemistry, Columbia University, Havemeyer Hall, New York, New York 10027, USA.
authors.forename: Mingji
authors.initials: M
authors.lastname: Dai
authors.forename: Isaac J
authors.initials: IJ
authors.lastname: Krauss
authors.forename: Samuel J
authors.initials: SJ
authors.lastname: Danishefsky
mesh_terms: D018360:Crystallography, X-Ray; D003521:Cyclopropanes / Q000737:chemistry; D005609:Free Radicals / Q000737:chemistry; D006571:Heterocyclic Compounds / Q000138:chemical synthesis*; D007202:Indicators and Reagents; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008968:Molecular Conformation; D010143:Paecilomyces / Q000737:chemistry; D013141:Spiro Compounds / Q000138:chemical synthesis*; D013237:Stereoisomerism
chemical_list: D003521:Cyclopropanes; D005609:Free Radicals; D006571:Heterocyclic Compounds; D007202:Indicators and Reagents; D013141:Spiro Compounds; C483569:spirotenuipesine A; C483570:spirotenuipesine B; C030797:cyclopropane