title: Synthesis of 3-epi-6,7-dideoxyxestobergsterol A.
abstract: 3-Epi-6,7-dideoxyxestobergsterol A (2), an analogue of xestobergsterol A, has been synthesized from dehydroepiandrosterone (3) in 15 steps. The key synthetic intermediate, 15beta,16alpha-dioxypregn-17(20)E-ene derivative 8, was prepared from the corresponding 15beta,16beta-epoxide 6 by treating with acetic acid and titanium tetraisopropoxide. The 23-oxo side chain was constructed stereoselectively by orthoester Claisen rearrangement of 8 followed by introduction of an isobutyl group. Basic treatment of the 15,23-diketone 12 followed by deprotection gave the title compound 2.
authors.affiliation: Department of Chemistry and Materials Science, Tokyo Institute of Technology, Meguro, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Kaji
authors.forename: T
authors.initials: T
authors.lastname: Koami
authors.forename: A
authors.initials: A
authors.lastname: Nakamura
authors.forename: Y
authors.initials: Y
authors.lastname: Fujimoto
mesh_terms: D000818:Animals; D002778:Cholestanones / Q000138:chemical synthesis* / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D011161:Porifera / Q000737:chemistry*
chemical_list: C419447:3-Epi-6,7-dideoxyxestobergsterol A; D002778:Cholestanones