title: Total Synthesis of (-)-Verrucarol(1).
abstract: We have achieved the total synthesis of (-)-verrucarol, a trichothecene sesquiterpenoid obtained as a hydrolysis product of the naturally occurring verrucarin A. Our total synthesis began with the previously reported enantiomerically pure bicyclic alpha-methylated gamma-lactone, which was prepared from D-glucose. The key steps for the total synthesis were (1) aldol-like carbon-carbon bond formation applied to the starting lactone using a four-carbon aldehyde as an electrophile for introduction of the quaternary stereogenic carbon sharing the B and C-rings of the trichothecene skeleton, (2) Dieckmann cyclization of the derived epsilon-ester lactone for construction of the C-ring equivalent, (3) Barton's decarboxylative oxygenation for conversion of a carboxylic acid functionality in the Dieckmann cyclization product into a hydroxyl group, (4) skeletal enlargement strategy for the crucial trichothecene skeleton construction, and (5) the final stereoselective formation of the exo-epoxy ring at the methylene carbon in the bridge constituting the B and C-rings.
authors.affiliation: Department of Applied Chemistry, Keio University, Hiyoshi, Kohoku-ku, Yokohama 223, Japan.
authors.forename: Jun
authors.initials: J
authors.lastname: Ishihara
authors.forename: Rie
authors.initials: R
authors.lastname: Nonaka
authors.forename: Yuki
authors.initials: Y
authors.lastname: Terasawa
authors.forename: Ryota
authors.initials: R
authors.lastname: Shiraki
authors.forename: Kazuo
authors.initials: K
authors.lastname: Yabu
authors.forename: Hiromi
authors.initials: H
authors.lastname: Kataoka
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Ochiai
authors.forename: Kin-ichi
authors.lastname: Tadano Ki