title: Coupling of sterically hindered trisubstituted olefins and benzocyclobutenones by C-C activation: total synthesis and structural revision of cycloinumakiol.
abstract: The first total syntheses of the proposed structure of cycloinumakiol (1) and its C5 epimer (18) are achieved in a concise and efficient fashion. Starting from the known 3-hydroxybenzocyclobutenone, 1 and 18 are obtained in nine and five steps with overall yields of 15% and 33%, respectively. The key for the success of this approach is the use of a catalytic C-C activation strategy for constructing the tetracyclic core of 1 through carboacylation of a sterically hindered trisubstituted olefin with benzocyclobutenone. In addition, the structure of the natural cycloinumakiol was reassigned to 19-hydroxytotarol (7) through X-ray diffraction analysis. This work demonstrates the potential of C-C activation for streamlining complex natural product synthesis.
authors.affiliation: Department of Chemistry, University of Texas at Austin, 100 East 24th street, Austin, TX 78712 (USA) http://gbdong.cm.utexas.edu/
authors.forename: Tao
authors.initials: T
authors.lastname: Xu
authors.forename: Guangbin
authors.initials: G
authors.lastname: Dong
mesh_terms: D000475:Alkenes / Q000138:chemical synthesis / Q000737:chemistry*; D002384:Catalysis; D018360:Crystallography, X-Ray; D003503:Cyclobutanes / Q000138:chemical synthesis / Q000737:chemistry*; D004224:Diterpenes / Q000138:chemical synthesis* / Q000737:chemistry; D008958:Models, Molecular; D028201:Pinaceae / Q000737:chemistry; D012238:Rhodium / Q000737:chemistry
chemical_list: C558232:11,10-oxymethylenecyclopent-14-isopropyl-8,11,13-podocarpatriene; D000475:Alkenes; D003503:Cyclobutanes; D004224:Diterpenes; C553737:cyclobutenone; D012238:Rhodium
keywords: CC activation; Rh catalysis; cycloinumakiol; structure elucidation; total synthesis