53 中員環の立体制御を用いたビシクロフムレノン及びペリプラノンAの全合成(口頭発表の部)

概要

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Bicyclohumulenone (1), sesquiterpene ketone isolated from a species of liverworts, Plagiochila acanthophlla subsp. japonica, is an attractive synthetic target because of its challenging structural features as well as its high level of aroma composition. The stereoselective synthesis of bicyclohumulenone was achieved in which the crucial 10-membered intermediate 2 was constructed by the intramolecular alkylation of the protected cyanohydrin 3. The E-cyclopropane ring at C(9) and C(10) was introduced stereoselectively by the 1,4-addition of dimethyloxosulfonium methylide to the enone 2. The stereoselectivity of this cyclopropanation was discussed based on MM2 calculations. The new structure of Periplanone A (17), the sex excitant pheromone of the American cockroach, has been proposed by Hauptmann based on its isolation and his synthesis. In his synthetic approach, the 1,4-relative stereochemistry between C(1) and C(8) in 17 was constructed by the highly stereoselective epoxidation (99:1) of the enone 21 using ^tBUOOH/KH. Our reexamination in this epoxidation based on MM2 calculations and experimental results showed that the epoxidation of 21 proceeded with nonstereoselectivity to give a mixture of 17 and 18 in a ratio of 1.3:1.
天然有機化合物討論会の論文
1988-09-26