P-30 天然8員環ラクトンAstakolactinの不斉全合成研究(ポスター発表の部)

• 柴本 健太郎

  東理大・理

• 福井 博喜

  東理大・理

• 椎名 勇

  東理大・理

書誌事項

タイトル別名

• P-30 Synthetic Studies on Astakolactin

抄録

Astakolactin (1), a sesterterpene metabolites. was isolated in 2003 from the sponge Cacospongia scalaris, collected from the gulf of Astakos, Greece. together with related compounds by Roussis et al. This compound contains two chiral centers and an unusual saturated 8-membered lactone moiety. First, we postulated that an optically active seco-acid of the eight-membered lactone could be constructed through the enantioselective aldol reaction of a ketene silyl acetal (KSA) with aldehyde promoted by Sn(OTf)_2 coordinated with a chiral diamine ligand. Second, effective lactonization using 2-methyl-6-nitrobenzoic anhydride (MNBA) with basic catalysts might then be applicable for producing the 8-membered lactone part of Astakolactin (1). Protection of the primary hydroxyl group in (E,E)-Farnesol was first carried out and oxidative cleavage of the terminal double bond was attained according to the literature method3 to afford aldehyde 12. Aldol reaction between aldehyde 12 with lithium enolate derived from ester 13 proceeded to form the corresponding coupling product 11. Oxidative deselenization of 11 produced (x-methylene-β-hydroxy ester 10, a key Morita-Baylis-Hillman intermediate. in high yield by our protocol.4 Reduction of the ester part in 10 followed by protection of the primary hydroxyl group in the resulting diol 17 afforded a secondary alcohol 18. Treatment of 18 with orthoester under the Johnson-Claisen rearrangement5 to produce the elongated ester 19. which was then converted to an aldehyde 20 by reduction, Aldol reaction of 20 with methyl propionate provided a mixture of the stereoisomers of 21. Successive protection of the secondary hydroxyl group in 21 and deprotection of TBDPS group produced the primary alcohol 23. After transformation of 23 to the corresponding seco-acid of the lactone moiety. the effective cyclization using benzoic anhydride will be examined in the next step.

収録刊行物

• 天然有機化合物討論会講演要旨集

  天然有機化合物討論会講演要旨集 49 (0), 569-574, 2007

  天然有機化合物討論会実行委員会

詳細情報

• CRID: 1390001206079608576
• NII論文ID: 110006682826
• DOI: 10.24496/tennenyuki.49.0_569
• ISSN: 24331856
• 本文言語コード: ja
• データソース種別:
  • JaLC
  • CiNii Articles
• 抄録ライセンスフラグ: 使用不可