title: An 8pi electron electrocyclization leading to a 9,19-methano-bridged analogue of 1 alpha,25-dihydroxyvitamin D3.
abstract: [reaction: see text] Lindlar semihydrogenation of a vitamin D type trienyne leads spontaneously to 9 alpha,19-methano-1 alpha,25-dihydroxyvitamin D3. The intermediate tetraene resulting from the reduction undergoes a rapid, stereoselective 8pi electron electrocyclization affording a novel steroid containing a linearly fused ABC (six-eight-six) 1,3,5-cyclooctatriene carbon framework.
authors.affiliation: Department of Chemistry, University of California, Riverside, California 92521, USA.
authors.forename: Rena
authors.initials: R
authors.lastname: Hayashi
authors.forename: Susana
authors.initials: S
authors.lastname: Fernández
authors.forename: William H
authors.initials: WH
authors.lastname: Okamura
mesh_terms: D001952:Bridged-Ring Compounds / Q000138:chemical synthesis; D002117:Calcitriol / Q000031:analogs & derivatives* / Q000138:chemical synthesis; D003500:Cyclization; D004583:Electrons; D013057:Spectrum Analysis
chemical_list: D001952:Bridged-Ring Compounds; D002117:Calcitriol