羧酸或取代羧酸是一类非常重要的有机化合物，其结构丰富，来源广泛，许多羧酸甚至可以直接从自然资源中获取。在化学反应中，羧基被认为是具有良好化学和区域选择性的离去基团，产物为CO₂气体，反应原子利用率高。此外，一些天然羧酸具有一个或多个手性中心，如果脱羧反应可以进行立体选择性或保留构型，则可用于合成光学纯的异构体。正因为这些特点，羧酸作为一种廉价易得的有机物经常应用于有机合成中，脱羧偶联是其中的一类重要的反应。然而，关于脱羧胺化类反应的研究报道较少。

基于此，本文主要开展了芳香羧酸的脱羧选择性胺化以及α-酮酸的脱羧酰胺化反应的研究，具体工作如下：

第一部分，研究了Cu(II)/Ag(I)催化的芳香羧酸与邻氨基苯甲酰胺的选择性脱羧胺化反应，以邻硝基苯甲酸和邻氨基苯甲酰胺的偶联作为模型反应，优化了催化剂种类及用量、碱、添加剂、溶剂、反应时间和温度等各影响因素。在最优反应条件[Cu(OTf)₂ (1.5 equiv.)，AgOTf (1.0 equiv.)，K₂CO₃ (2 equiv.)，4Å MS (160 mg)，DMSO (2.0 mL)，Ar保护，120 °C，24 h]下，模型反应的产率为62%，且通过X射线单晶衍射分析，进一步确认产物结构为芳香胺的选择性N-芳基化产物。该催化体系下，底物适用性研究结果表明各种不同取代的邻硝基苯甲酸与含各种取代的邻氨基苯甲酰胺的偶联反应都可以顺利进行，以中等产率合成了17个二芳基胺类化合物，其中有14个为新化合物。同时，我们提出了Cu/Ag共催化芳香羧酸和邻氨基苯甲酰胺的选择性脱羧胺化的反应机理。该反应为取代邻氨基苯甲酰胺的选择性胺化提供了一种新思路。

第二部分，研究了无金属催化下α-酮酸与叠氮试剂的脱羧酰胺化反应，以苯甲酰甲酸与叠氮磷酸二苯酯(DPPA)的酰胺化作为模型反应，优化了叠氮试剂、碱、反应溶剂、反应温度和时间等各影响因素。在最优反应条件[K₃PO₄ (2.0 equiv.)，DMF (2.0 mL)，100 °C，24 h]下，模型反应的产率为91%。该催化体系下的底物适用性研究结果表明各种取代的苯甲酰甲酸、萘环乙醛酸以及杂环乙醛酸都可顺利进行，以71-95%产率合成了20种芳香酰胺类化合物。

综上，本文建立了两种脱羧胺化催化体系，实现了芳香羧酸与同时含有氨基和酰胺基团底物的选择性脱羧胺化以及α-酮酸与叠氮试剂的脱羧酰胺化。两种催化体系发展和完善了芳香羧酸脱羧构建碳-氮键的方法。

Carboxylic acid or substituted carboxylic acid is a kind of very important organic compounds, which has rich structural diversity and has a wide range of sources. Many carboxylic acids can even be obtained directly from natural resources. In chemical reaction, carboxyl group is considered to be a good chemical and regionally selective ionized group. The product is CO₂ gas, which has high atomic utilization rate. In addition, some natural carboxylic acids have one or more chiral centers and can be used to synthesize optically pure isomers if the decarboxylation reaction can be stereoselective or configuration-preserving. Because of these characteristics, carboxylic acids are often used in organic synthesis as a cheap and readily available organic compound, among which decarboxylation coupling is one of the most important reactions. However, there are few reports on decarboxylation amination reactions.

Based on this, the decarboxylation selective amination of aromatic carboxylic acids and the decarboxylation amidation of α-keto acids were studied in this paper.

In the first part, the selective decarboxylation of aromatic carboxylic acid with o-aminobenzamide catalyzed by Cu(II)/Ag(I) was studied. The coupling of o-nitrobenzoic acid and o-aminobenzamide was used as a model reaction to optimize the influence factors of catalyst type and dosage, base, additive, solvent, reaction time and temperature. Under the optimum reaction conditions [Cu(OTf)₂ (1.5 equiv.), AgOTf (1.0 equiv.), K₂CO₃ (2 equiv.), 4Å MS (160 mg), DMSO (2.0 mL), Ar protection, 120 °C, 24 h], the yield of the model reaction was 62%. The structure of the product was further confirmed to be the selective N-aromatization product of aromatic amines by X-ray single crystal diffraction analysis. Under this catalytic system, the results of substrate applicability showed that the coupling reaction of various substituted o-nitrobenzoic acid with o-aminobenzamide containing various substitutes could proceed smoothly and 17 diarylamines were synthesized in medium yield, of which 14 were new compounds. At the same time, the mechanism of selective decarboxylation of aromatic carboxylic acid and o-aminobenzamide catalyzed by Cu/Ag was proposed. This reaction provides a new idea for selective amination of o-aminobenzamide.

In the second part, the decarboxylation amidation of α-keto acids with azide reagent catalyzed by non-metal was studied. Taking the amidation of benzoyl formic acid with diphenyl azide phosphate (DPPA) as a model reaction, the influencing factors such as azide reagent, base, reaction solvent, reaction temperature and time were optimized. Under the optimum reaction conditions [K₃PO₄ (2.0 equiv.), DMF (2.0 mL), 100 °C, 24 h], the yield of the model reaction was 91%. Substrate applicability of the catalytic system showed that all kinds of substituted benzoyl formic acid, naphthalene cyclohexanoic acid and heterocyclic glyoxylic acid could proceed smoothly. Twenty aromatic amides were synthesized in 71-95% yield.

In summary, two kinds of catalytic systems for decarboxylation amination have been established to achieve selective decarboxylation of aromatic carboxylic acids with substrates containing both amino and amide groups, and decarboxylation of α-keto acids with azide reagents. Two catalytic systems have developed and improved the methods of decarboxylation of aromatic carboxylic acids to construct C-N bonds.

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