著者

井原 正隆 川口 明洋 加藤木 守 千尋 正利 福本 圭一郎 亀谷 哲治

出版者

天然有機化合物討論会実行委員会

雑誌

天然有機化合物討論会講演要旨集

巻号頁・発行日

vol.28, pp.339-346, 1986

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Synthesis of angularly tricyclopentanoid sesquiterpenes, was investigated via tricyclo[7.3.0.0^<1,5>]dodecane derivatives using intramolecular Diels-Alder reaction or intramolecular double Michael reaction as a key step. (1) Highly Stereoselective Total Synthesis of (±)-3-Oxosilphinene via Intramolecular Diels-Alder Reaction-(E,E)-3-(8-Phenylthio-octa-5,7-dien-2-yl)-2-methyl-2-cyclopenten-1-one (19) was prepared from the bromocyclopentenone (16) in three steps. Cycloaddition of 19 gave only one stereoisomer of the tricyclo[7.3.0.0^<1,5>]dodecene (20) having all correct four contiguous asymmetric centers. The cyclo-adduct (20) was converted into the tricyclo[6.3.0.0^<4,8>]undecane (25) via Wolff rearrangement. According to usual procedures, the ester (25) was then transformed into (±)-3-oxosilphinene (1). (2) Synthetic Study of Pentalenene and Pentalenic Acid via Intramolecular Double Michael Reaction-Barbier reaction of 4,4-dimethyl-2-cyclopenten-1-one (34) followed by oxidation with pyridinium chlorochromate gave the enone (36), which was converted into the bis-enone (33) in four steps. Intramolecular double Michael reaction of 33, carried out by heating with trimethylsilyl chloride, triethylamine, and zinc chloride, gave tricyclo[7.3.0.0^<1,5>]dodecanediones (40), which were subjected to Wolff rearrangement to afford the tricyclo[6.3.0.0^<4,8>]undecanes (41) possessing all carbon skeleton of natural products (4 and 5).