title: Construction of the septahydroxylated ABC-ring system of dihydro-β-agarofurans: application of 6-exo-dig radical cyclization.
abstract: A synthetic route to the septahydroxylated ABC-ring system of dihydro-β-agarofurans was established. The B-ring was formed by a base-promoted diastereoselective Diels-Alder reaction between 3-hydroxy-2-pyrone and a d-glyceraldehyde-derived dienophile, while the C-ring was cyclized by PhSeCl-mediated etherification. The remaining A-ring was constructed via a 6-exo-dig radical reaction. Selective transformations gave rise to the ABC-ring system 1 with nine contiguous stereocenters. The thus obtained 1 corresponded to the enantiomer of the densely oxygenated core structure of dihydro-β-agarofurans.
authors.affiliation: Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan. inoue@mol.f.u-tokyo.ac.jp.
authors.forename: Hiroki
authors.initials: H
authors.lastname: Fujisawa
authors.affiliation: Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan. inoue@mol.f.u-tokyo.ac.jp.
authors.forename: Tomochika
authors.initials: T
authors.lastname: Ishiyama
authors.affiliation: Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan. inoue@mol.f.u-tokyo.ac.jp.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Urabe
authors.affiliation: Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan. inoue@mol.f.u-tokyo.ac.jp.
authors.forename: Masayuki
authors.identifier: http://orcid.org/0000-0003-3274-551X
authors.initials: M
authors.lastname: Inoue