52 4-メチルトロポロンを出発物質としたパルセニンの合成(口頭発表の部)

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概要

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• The total syntheses of hymenolin (50) and and parthenin (52) have been established starting from 4-methyltropolone (2). The synthetic strategy is shown in Scheme 1. The regioselective tosylation of 2 and successive condensation of the resulting tosylate (5) with diethylmalonate gave 2H-cycloheptatblfuran-2-one derivative (7). The catalytic hydrogenation of 7 gave the desired saturated lactone (12) in which C_6-Me and Y-lactone ring were situated in cis. Various attempts of alkylation or functionalization at C_7-position of ketone 10 were unsuccessful. The attempt of the syntheses of intermediates 20 and 21 via cycloaddition of dichloroketene to the olefin 15 was also unsuccessful because of their poor yields as shown in Scheme 3. The 1,4-addition of Grignard reagent (33) to the α,β-unsaturated ketone (29) which was derived from 15 and successive methylation of the resulting 30 gave a mixture of α- and β-methyl derivatives, 31 and 32. Acid catalyzed aldol condensation of benzoate 36, which was derived from 32, gave the desired product (38) in a moderate yield. Reduction of 38 with LiAl(OMe)_3H gave a β-alcohol (40) as major product. Platinum catalyzed air oxidation of 40 and successive Jones oxidation gave a cyclopentanone derivative (42). The conversion of 42 to hymenolin (50) was achieved by the analogous procedure reported by Heathcock and his coworkers in their synthesis of parthenin. Successive treatmnt of 50 with LDA and CBr_4 gave an α-bromolactone (51) as the sole product. Treatment of 51 with DBU gave parthenin (52), which was identical with natural product.

• 天然有機化合物討論会の論文
• 1988-09-26

著者

• 安東 政義

  東北大理

• 高瀬 嘉平

  Department of Chemistry, Faculty of Science, Tohoku University

• 安並 正文

  東北大理

• 薊 英範

  東北大理

• 日下 晴彦

  東北大理

• 和田 勝昭

  東北大理

• 高瀬 嘉平

  東北大理

• 高瀬 嘉平

  Department Of Chemistry Faculty Of Science Tohoku University

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