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首页> 外文学位 >Exploration of alpha-Diazocarbonyl Compounds for Transition-Metal Catalyzed Carbon-Carbon Bond Formations. Development of Palladium-Catalyzed Stereoselective Synthesis of Trisubstituted Alkenes and the Synthesis of Quaternary alpha,alpha-Heterodiaryl Carboxylic Acids by Rhodium-Catalyzed Multi-Component Coupling Reactions.
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Exploration of alpha-Diazocarbonyl Compounds for Transition-Metal Catalyzed Carbon-Carbon Bond Formations. Development of Palladium-Catalyzed Stereoselective Synthesis of Trisubstituted Alkenes and the Synthesis of Quaternary alpha,alpha-Heterodiaryl Carboxylic Acids by Rhodium-Catalyzed Multi-Component Coupling Reactions.

机译：探索用于过渡金属催化的碳-碳键形成的α-重氮羰基化合物。铑催化的多组分偶合反应在钯催化的立体选择性合成三取代的烯烃上的发展和季铵的α，α-杂二芳基羧酸的合成。

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摘要

Transition-metal catalyzed cross-coupling reactions with alpha-diazocarbonyl compounds for C-C bond formation have been explored. Our study demonstrated that alpha-diazocarbonyl compounds can effectively couple with organopalladium(II) complexes, and a reactive palladium-carbene would be formed. It is believed that highly reactive metal-carbene complexes would undergo migratory carbene insertion to afford new organopalladium complexes. In this research, the diazoesters cross-coupling reactions have been exploited for stereoselective synthesis of (E)-alpha,beta-diarylacrylates, which are important scaffolds for some bioactive compounds. In Chapter 2, we developed the Pd-catalyzed cross-coupling of benzyl bromides with diazoesters, and the (E)-alpha,beta-diarylacrylates were obtained in up to 92% yield and >20:1 E-selectivity. The cross-coupling reaction is mediated by the benzylpalladium(II) complexes, which were formed by the classical oxidative addition of the bromides. However, the benzyl bromide reactions suffered from the excessive usage of the diazo reagents and the phosphine ligand.;To develop a more general and environmentally friendly diazoesters coupling reactions, we accomplished the Pd-catalyzed oxidative arylboronic acids coupling of diazoesters to furnish (E)-alpha,beta-diarylacrylates in excellent yields and stereoselectivity. Notably, this reaction exhibits excellent efficiency involving the use of 1.2 equiv arylboronic acids and dioxygen as the sole oxidant. Mechanistically, this catalytic coupling reaction involves arylpalladium(II) intermediates, which were produced by transmetallation with arylboronic acids. Sequential diazoesters coupling and beta-hydride elimination produced the product acrylate and palladium-hydride species, which should be transformed by the action of dioxygen to some catalytically active palladium(II) complexes.;Apart from alkene formation, tandem C-C bond formation at the carbenic center has also been achieved with catalytic diazoesters cross-coupling reaction as the principal step. Analogous to Pd(II) center, d8 arylrhodium(I) complexes would undergo diazoesters coupling reactions. Our study showed that [Rh(cod)OH]2 can effect catalytic cross-coupling of arylboronates and diazoesters to afford oxa-pi-allylrhodium(I) complexes. In the presence of KOtBu and alkyl halides, tandem alkylation of the allyl complexes were achieved leading to the formation of a quaternary stereocenter at the carbenic carbon. Our study demonstrates the versatility of metal-carbene in the development of highly efficient cascade C-C bond formations, which would be useful for creating molecular structures of higher complexity.
机译：已经探索了过渡金属催化的与α-重氮羰基化合物形成C-C键的交叉偶联反应。我们的研究表明，α-重氮羰基化合物可以有效地与有机钯（II）配合物偶联，并形成反应活性的钯-卡宾。相信高反应性的金属-卡宾配合物将经历迁移卡宾插入以提供新的有机钯配合物。在这项研究中，重氮酯的交叉偶联反应已被用于立体选择性合成（E）-α，β-二芳基丙烯酸酯，这是一些生物活性化合物的重要支架。在第2章中，我们开发了Pd催化的苄基溴与重氮酸酯的交叉偶联，并以高达92％的收率和> 20：1的E-选择性获得了（E）-α，β-二芳基丙烯酸酯。交叉偶联反应由苄基钯（II）配合物介导，该配合物是通过经典的溴化物氧化加成反应形成的。然而，苄基溴反应由于重氮试剂和膦配体的过量使用而遭受苦难。为了开发一种更通用和对环境友好的重氮酯偶联反应，我们完成了重氮催化Pd催化的重氮芳基硼酸偶联至配料（E）的过程。 -α，β-二芳基丙烯酸酯具有优异的收率和立体选择性。值得注意的是，该反应显示出优异的效率，包括使用1.2当量的芳基硼酸和双氧作为唯一的氧化剂。从机理上讲，这种催化偶联反应涉及芳基钯（II）中间体，该中间体是通过与芳基硼酸进行金属转移生成的。依次进行重氮酯偶联和消除β-氢化物可生成丙烯酸酯和氢化钯产物，应通过双氧作用将其转化为某些具有催化活性的钯（II）配合物。;除烯烃形成外，在羧基上形成串联CC键以催化重氮酯的交叉偶联反应为主要步骤也达到了中心。类似于Pd（II）中心，d8芳基铑（I）络合物将经历重氮酸酯偶联反应。我们的研究表明，[Rh（cod）OH] 2可以实现芳基硼酸酯和重氮酸酯的催化交叉偶联，从而提供oxa-pi-allyrhodium（I）配合物。在存在KOtBu和烷基卤化物的情况下，实现了烯丙基配合物的串联烷基化，从而导致在羧碳上形成了一个立体立体中心。我们的研究证明了金属卡宾在高效级联C-C键形成过程中的多功能性，这对创建更高复杂性的分子结构很有用。

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  • 作者

    Tsoi, Yuk Tai.;

  • 作者单位

    Hong Kong Polytechnic University (Hong Kong).;

  • 授予单位 Hong Kong Polytechnic University (Hong Kong).;
  • 学科 Organic chemistry.
  • 学位 Ph.D.
  • 年度 2012
  • 页码 307 p.
  • 总页数 307
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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