Clarification of Reaction Routes and Synthetic Application regarding Specific Decarbonylative α-Arylation of Carboxylic Acids in Acidic Media

2-发现甲氧基烷酸在P_2O_5-MsOH中发生连续的脱羰基α，α-二芳基化反应，而不是在羰基碳上发生Friedel-Crafts型芳基化反应。从反应产率的角度阐明了芳烃取代基和羧酸取代基对反应的影响。反应行为主要受羧酸上α-取代基的吸/放电子性质和芳烃的正物种接受能力的控制。空间位阻是决定反应可行性的次要因素，并对α-酮基羧酸脱羰基α-芳基化反应的具体反应行为和反应路线进行了阐明，包括反应机理的初步研究。此外，还研究了以异辛酸为原料合成新型共轭分子的反应。主题1：羧酸类表面活性剂结构要求的阐明 ...更多信息 用于脱羰基α-芳基化的底物。阐明了α-取代基的形式对反应行为的影响以及芳环上取代基的空间效应和电效应。通过对α-烷基（α-芳基）的空间位阻和电子效应的半定量估算，发现反应行为可根据脱羰的可行性和芳基化的次数分为4类。明确了反应类型与α-酮基羧酸结构之间的关系。主题二：杂原子在缩合反应中的作用。- 使2-甲氧基丙酸、甲氧基乙酸和甲氧基苯乙酸与芳烃在五氧化二磷（P2 O 5）、多磷酸（PPA）、甲磺酸混合物（P2 O 5-MsOH）、甲磺酸（MsOH）、三氟甲磺酸（TfOH）、Nafion-H、多磷酸乙酯或多磷酸三甲基甲硅烷基酯的存在下反应。结果表明，α-甲氧基羧酸的脱羰基α-芳基化反应强烈依赖于酸性介质的性质。这些行为也被证明是每个调解人的特点。特别是，产品分布和酸性介质的性质之间的关系，如酸度功能值评估甲氧基乙酸显示出更明显的依赖于介质比其他羧酸。然而，对整个反应行为的一般性解释还没有得到澄清。主题3：基于中间体候选物的模型反应确定反应路线和机理。- 已对2-甲氧基丙酸的反应路线进行了澄清。对甲氧基乙酸的研究表明，该反应的进行方式与其它α-甲氧基羧酸不同。在甲氧基乙酸与TfOH的反应中，Friedel-Crafts酰化反应伴随着重排反应沿着α-芳基化反应的进行。少

2-Methoxyalkanoic acids were found to undergo consecutive decarbonylative a, a-diarylation in P2O5-MsOH instead of Friedel-Crafts type arylation on the carbonyl carbon. The influences of the substituents of the arenes and the carboxylic acids in this reaction were elucidated on the basis of the reaction yields. The reaction behavior was found to be primarily governed by the electron-withdrawing/releasing property of the a-substituents on the carboxylic acids as well as the positive species-accepting ability of the arenes. The steric hindrance was shown to participate in determining the reaction feasibility as a secondary factor.Elucidation of the exact reaction behaviors and clarification of reaction routes including rough reaction mechanism for decarbonylative a-arylation of a-ketocarboxylic acids were also performed. In addition, synthetic reaction of novel conjugated molecules from pyruvic acid was investigated.Theme 1 : Clarification of structural requirements of carboxylic acid su … More bstrates for decarbonylative a-arylation. -Influence of the form of a-substituents on reaction behavior and steric and electric effects of the substituents on the aromatic ring were elucidated. Furthermore, semi-quantitative estimation of steric and electric effects of the a-alkyl (a-aryl) groups revealed that the reaction behaviors are divided into 4 types according to the feasibility of decarbonylation and the number of arylation. The relation between the type of the reaction and the structure of a-ketocarboxylic acids is clearly interpreted.Theme 2 : Elucidation of the role of the hetero atoms in condensation mediators. - 2-Methoxypropanoic, methoxyacetic, and methoxyphenylacetic acids were allowed to react with arenes in the presence of phosphorus pentoxide (P2O5), polyphosphoric acid (PPA), methanesulfonic acid mixture (P2O5-MsOH), methanesulfonic acid (MsOH), trifluoromethanesulfonic acid (TfOH), Nafion-H, polyphosphoric acid ethyl ester, or polyphosphoric acid trimethylsilyl ester. As a result, the reaction behavior of decarbonylative a-arylation of a-methoxycarboxylic acids was proved to be strongly dependent on the nature of the acidic mediators. These behaviors were also shown to be characteristic for each mediator. Particularly, the relation between product distribution and the nature of the acidic mediator such as acidity function value evaluated for methoxyacetic acid showed more distinct dependence on the mediator than those of other carboxylic acids. However, general explanation for the whole reaction behavior has not been clarified yet.Theme 3 : Determination of reaction routes and mechanism based on the model reaction of the intermediate candidates. - Clarification of the reaction route has been performed for the reaction of 2- methoxypropanoic acid. Contrarily, investigation on that for methoxyacetic acid revealed that the reaction propagates with different ways from those observed in the reaction of other a-methoxycarboxylic acids. In the reaction of methoxyacetic acid with TfOH, Friedel-Crafts acylation type reaction followed by rearrangement concurrently was observed to propagate along with decarbonylative a-arylation. Less