Studies on 5-8 Fused Ring Compounds. VII. The Conformations of the Eight-Membered Rings in C<sub>6</sub>–C<sub>8</sub>–C<sub>5</sub>Fused Ring Compounds
作者:Misao Umehara、Hiromi Honnami、Shinzaburo Hishida、Takashi Kawata、Shigeru Ohba、Shonosuke Zen
DOI:10.1246/bcsj.66.2983
日期:1993.10
C6–C8–C5 fused ringcompound, tricyclo[9.4.0.04,8]pentadecane-2,9-dione were synthesized by photocycloaddition of decalin-1,3-dione to cyclopentene. The conformational analyses were carried out by MM2 and the results were compared with X-ray analyses. The eight-membered rings take predominantly boat-chair forms although those in C5–C8–C5 fused ringcompounds exist in various conformations.
Furannulation strategy for synthesis of the naturally occurring fused 3-methylfurans: efficient synthesis of evodone and menthofuran and regioselective synthesis of maturone via a Lewis acid catalyzed Diels-Alder reactions. Some comments for its mechanistic aspects
作者:Mariko Aso、Akio Ojida、Guang Yang、Ok Ja Cha、Eiji Osawa、Ken Kanematsu
DOI:10.1021/jo00067a031
日期:1993.7
Fused 3-methylfurans are readily obtained by the reaction of allenic sulfonium salt 1 and the enolate anions of cyclic 1,3-dicarbonyl compounds in two steps. Using these fused 3-methylfuran compounds as intermediates, furanoterpenoids such as menthofuran (8) and evodone (4b) are synthesized efficiently. Moreover, maturone (15) is also obtained regioselectivity by Lewis acid CatalYzed Diels-Alder reaction of benzofuranquinone (12) with piperylene. In the context with the regioselectivity observed in the Diels-Alder reaction of 12, semiempirical molecular orbital calculations are applied to gain its theoretical interpretation based upon frontier molecular orbital theory and transition state analysis.