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  • 學位論文

Discovery of New Carbocyclizations Involving Activation of C–C Multiple Bonds by Electrophilic Noble Metals

指導教授 : 劉瑞雄

摘要


本論文共分成四個章節,主要是探討利用過渡金屬金和鉑催化不同的有機小分子 化合物。利用此類親炔類的過渡金屬催化,將非環類的基質經由特殊的化學選擇 性合成出環碳化合物以及雜環化合物。 第一章節我們發表利用AuCl3 將6-取代-順式-4,6-雙烯-1-炔-3-醇類化合物經由 6-exo-dig 形成烯丙基羰陽離子,接著進行片吶醇重排反應生成含醛類的環戊烯 基的架構。此類的環化異構化反應不僅提供了具化學選擇性的合成各種醛類的環 戊烯基衍生物,也發展出一個嶄新的合成路徑。而最後也利用了具掌性的醛類基 質環化進行探討。 第二章節利用鉑(II)金屬錯合物催化2-炔類-1 羰基苯與丙烯基矽烷經由其氧炔類 官能基和2-取代丙烯基矽烷進行新形式一鍋化烯丙基化以及環化反應。此反應經 由一連串的骨牌式反應包含了羰基的烯丙基化反應,炔類的烷氧基化以及新型式 的不飽和-氧正離子環化反應。 第三章節是我們發表了利用金金屬錯合物催化烯丙基化以及烯炔類的環化反應 生成1,3 取代的芳香環化合物。利用PPh3AuCl/AgOTf(5/3 mol %)催化炔醛類分 子與2-取代烯丙基矽烷生成1,3 取代的芳香環化合物。此類反應經由醛類的烯丙 基化接著進行烯炔類的環化異構化反應而生成,此兩步反應中催化劑PPh3AuOTf 都扮演著重要的角色。 第四章節我們以金(I)金屬錯合物催化不飽和丙二烯-乙縮醛官能基,合成具立體 選擇性的雙環[3.2.1]辛烷-6-烯-2-酮類化合物。此類的環化反應其反應機構是經由 sp3 混成的碳氫鍵經由1,3 加成至乙烯基類甲烯片段上進行反應。

關鍵字

催化

並列摘要


This dissertation describes development of some new catalytic systems involving gold and platinum salts. The use of these soft alkynophilic metals enables mild, chemoselective and efficient transformations of a variety of readily available acyclic substrates to a wide range of synthetically useful carbocyclic and heterocyclic products. For better understanding the thesis is divided into four chapters. The first chapter describes a novel AuCl3-catalyzed cyclization of 6-substituted cis-4,6-dien-1-yn-3-ols which proceeds via a 6-exo-dig pathway to give allyl cations, which subsequently undergoes a pinacol rearrangement to produce cyclopentenyl aldehyde core. This cycloisomerization of enynes via the intermediacy of allyl cation not only offered a chemoselective method for the preparation of cyclopentenyl aldehyde derivative but also opens up unprecedented reaction routes. Using chiral alcohol substrates, such cyclizations proceed with reasonable chirality transfer. The second chapter deals with a new one-pot Pt(II)-catalyzed synthesis of 9-oxabicyclo[3.3.1]nona-2,6-dienes from readily available 2-alkynyl-1-carbonylbenzenes and allylsilanes through tandem allylation/annulation of the oxo-alkyne functionalities with 2-substituted allylsilanes. This reaction sequence is proposed to proceed through three domino reactions including allylation of the carbonyl group, hydroalkoxylation of the alkyne, and a new ene-oxonium annulation. The third chapter describes the gold-catalyzed synthesis of 1,3-disubstituted aromatic rings through tandem allylation/enyne cyclization reaction. Treatment of alkynals with 2-substituted allylsilanes and PPh3AuCl/AgOTf (5/3 mol %) catalyst leads to the formation of 1,3-disubstituted benzenes efficiently. This reaction sequence comprises an initial allylation of aldehyde, followed by cycloisomerization of enynes; PPh3AuOTf is active in both steps. The last chapter discusses a stereoselective synthesis of bicyclo[3.2.1]oct-6-en-2-ones through Au(I)-catalyzed cycloisomerization of an allenene-acetal functionality. This cyclization is mechanistically significant because it involves an unprecedented 1,3-addition of a sp3-hybridized C–H bond to vinylcarbenoid moiety.

並列關鍵字

gold platinum catalyst

參考文獻


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