title: Chemistry and structural determination of botcinolides, botcinins, and botcinic acids.
abstract: The first asymmetric total syntheses of botcinins C (18), D (19), E (20), and F (21), botcinic acid (22), botcinic acid methyl ester (23), botcineric acid (26), and 3-O-acetylbotcinic acid methyl ester () were achieved. The structures of these compounds have been unequivocally determined through their total syntheses and those of 20, 22, 23, 26, and are identified with the revised forms of the natural products formerly assumed to be 2-epibotcinolide (10), botcinolide (6), 4-O-methylbotcinolide (7), homobotcinolide (11), and 3-O-acetyl-5-O-methylbotcinolide (8), respectively. It was further proved that the proposed nine-membered ring structure of 2-epibotcinolide (10) is very unstable and the ineluctable translactonization easily occurred to form the corresponding gamma-lactone .
authors.affiliation: Department of Applied Chemistry, Faculty of Science, Tokyo University of Science, Kagurazaka, Shinjuku-ku, Tokyo 162-8601, Japan. shiina@rs.kagu.tus.ac.jp.
authors.forename: Isamu
authors.initials: I
authors.lastname: Shiina
authors.forename: Hiroki
authors.initials: H
authors.lastname: Fukui
mesh_terms: D003651:Decanoates / Q000138:chemical synthesis* / Q000737:chemistry / Q000302:isolation & purification; D007783:Lactones / Q000138:chemical synthesis* / Q000737:chemistry / Q000302:isolation & purification; D011753:Pyrones / Q000138:chemical synthesis* / Q000737:chemistry / Q000302:isolation & purification
chemical_list: D003651:Decanoates; D007783:Lactones; D011753:Pyrones; C530928:botcinin C; C530929:botcinin D; C511119:botcinin E; C511120:botcinin F; C101236:botcinolide