Asymmetric Total Synthesis of (–)‐Azaspirene by Utilizing Ti‐Claisen Condensation and Ti‐Direct Aldol Reaction

DOI Web Site Web Site 被引用文献6件
  • Mikiko Sugi
    Department of Chemistry School of Science and Technology Kwansei Gakuin University 2‐1 Gakuen 669‐1337 Sanda Hyogo Japan
  • Ryohei Nagase
    Department of Chemistry School of Science and Technology Kwansei Gakuin University 2‐1 Gakuen 669‐1337 Sanda Hyogo Japan
  • Tomonori Misaki
    Graduate School of Material Science University of Hyogo 3‐2‐1 Kohto 678‐1297 Kamigori Hyogo Japan
  • Hidefumi Nakatsuji
    Department of Chemistry School of Science and Technology Kwansei Gakuin University 2‐1 Gakuen 669‐1337 Sanda Hyogo Japan
  • Yoo Tanabe
    Department of Chemistry School of Science and Technology Kwansei Gakuin University 2‐1 Gakuen 669‐1337 Sanda Hyogo Japan

書誌事項

公開日
2016-10
権利情報
  • http://onlinelibrary.wiley.com/termsAndConditions#vor
DOI
  • 10.1002/ejoc.201600766
公開者
Wiley

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説明

<jats:p>A successful asymmetric total synthesis of (–)‐azaspirene has been accomplished by utilizing (3<jats:italic>R</jats:italic>)‐6‐cinnamyl‐3‐methyl‐3‐phenyl‐1,4‐dioxane‐2,5‐dione, a readily accessible chiral template. The present method involves two distinctive TiCl<jats:sub>4</jats:sub>/amine‐mediated reactions: (i) an asymmetric Ti‐crossed‐Claisen condensation of the chiral template with propanoyl chloride followed by methanolysis to afford methyl (2<jats:italic>R</jats:italic>)‐(4<jats:italic>E</jats:italic>)‐2‐hydroxy‐5‐phenyl‐2‐propanoylpent‐4‐enoate, the key chiral synthon and (ii) a robust Ti‐direct aldol addition reaction, instead of the reported lithium diisopropylamide/hexamethylphosphorictriamide (LDA/HMPA) or potassium hexamethyldisilazide (KHMDS)‐mediated reaction, by using the trimethylsilyl (TMS) ether of α‐acyl‐γ‐lactam to successfully furnish the new aldol adduct. Final oxidation, cyclization, and <jats:italic>tert</jats:italic>‐butyldimethylsilyl (TBS) removal produced (–)‐azaspirene from the key template in 23 steps (total yield 1.7 %).</jats:p>

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