Total Synthesis of (+)-Isolaurepinnacin. Use of Acetal-Alkene Cyclizations To Prepare Highly Functionalized Seven-Membered Cyclic Ethers

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• 作者：Daniel Berger ; Larry E. Overman ; and Paul A. Renhowe
• 刊名：Journal of the American Chemical Society
• 出版年：1997
• 出版时间：March 12, 1997
• 年：1997
• 卷：119
• 期：10
• 页码：2446 - 2452
• 全文大小：403K
• 年卷期：v.119,no.10(March 12, 1997)
• ISSN：1520-5126

文摘

The first synthesis of the title compound is described.The synthesis features an acetal-vinylsilanecyclizationto stereoselectively form the cis-2,7-disubstituted oxepenering and introduce ⁴ unsaturation. Starting with(2R,3S)-2,3-epoxypentan-1-ol (16), mixed acetal 10 isformed in five steps and 72% overall yield. Treatment of10 withexcess BCl₃ in CH₂Cl₂ at -78 0 C promotes cyclization to afford ⁴-oxepene39 in 90% yield after deprotectionof the silyl ether. Elaboration of the (E)-enynefunctionality of the six-carbon side chain completes the synthesisof(+)-isolaurepinnacin.