【作者】 姬小趁；

【导师】 江焕峰；

【作者基本信息】 华南理工大学 ， 应用化学， 2014， 博士

【摘要】 过渡金属催化的化学反应在有机合成化学中具有广泛的应用。特别是钯催化的反应过程通常具有成键的多样性，较高的化学、区域和立体选择性，以及较好的官能团耐受性等特点，因此成为一种高效的合成多官能团化复杂化合物的有效方法。钯催化剂的催化活性和选择性可以通过反应体系中配体、溶剂、温度和添加剂等条件的改变来调控。氧化反应是有机化学的重要组成部分，并且高选择性以及条件温和的氧化反应成为现代有机合成化学的发展方向。钯催化的氧化反应体系目前所用的氧化剂有Cu2+盐、苯醌、DDQ、PhI(OAc)2、K2S2O8等，这些氧化剂不仅价格昂贵而且通常会产生对环境有害的副产物。毫无疑问，氧气是一种资源丰富、廉价易得、原子经济性高并且环境友好的理想氧化剂，反应结束后以H2O的形式释放出来从而减少了对环境的污染。近年来，分子氧参与钯催化的反应引起了全世界化学工作者的广泛关注。这类反应通常能够降低成本、提高反应的原子经济性以及简化产物的分离过程，并且在大多情况下都能够改善反应的选择性。Pd(II)/O2催化体系在实验室研究以及工业生产上都有着广泛的应用。本课题致力于以绿色化学为导向，以简单烯烃为原料的钯催化氧气氧化的新型有机合成方法学研究，实现了多种含氮功能有机分子的高效构建。这些新颖的合成方法在天然产物全合成，医药、农药以及功能材料等领域有广泛的应用前景。具体的研究内容如下：（1）基于分子氧参与钯催化Csp2─Csp2键构建的氧化环化反应，高效地构建了一系列2-取代和2,3-二取代喹啉类衍生物。该方法作为经典Povarov反应的补充，提供了一种多取代喹啉类化合物的高效合成策略。此外，该反应的底物适用性比较好，具有原料廉价易得、条件温和、原子经济性高等优点。（2）分子氧参与钯催化芳基胺、醛和末端烯烃的选择性氧化环化反应，简便地构建一系列1,4-二氢吡啶类化合物。我们也对非对称1,4-二氢吡啶的合成进行了初步的探索。通过控制性实验研究，我们发现顺式烯胺化合物是该反应的一个重要中间体。（3）分子氧参与钯催化活化烯烃的去氢胺卤化反应。该反应具有非常好的区域和立体选择性以及官能团的耐受性，并且直接以简单的芳香胺作为氮源。该反应提供了一种非常简便的合成策略来构建用其他方法很难制备的卤代烯胺骨架结构，反应条件也比较温和。（4）分子氧参与钯催化芳基伯胺与烯烃的氧化偶联反应。该反应能够高效地、高区域和立体选择性地构建一系列顺式烯胺类化合物，并且这些化合物可用来合成多种含氮杂环化合物（如吲哚、吡唑、吡咯、1,4-二氢吡啶）。反应体系中的添加剂LiBr对反应的顺利进行起了非常重要的作用，它可以抑制由芳基伯胺与钯催化剂的强配位作用而导致的催化剂失活。（5）溶剂调控的选择性钯催化烯烃与芳基胺的氧化反应。在30%H2O2以及1个大气压氧气共同作氧化剂的条件下，使用DMF作溶剂时能够选择性地发生烯烃的去氢胺卤化反应；使用THF作溶剂时能够选择性地发生苯环上溴代以及与烯烃的氧化偶联反应。更多还原

【Abstract】 Transition-metal-catalyzed transformations have been found extensive applications inSynthetic Organic Chemistry. Especially, palladium-catalyzed reactions generally featureddiversity in chemical bond formation, excellent chemo-, regio-, stereoselectivities, as well asgreat tolerance of functional groups. Therefore, it constitutes an efficient strategy tosynthesize multifunctional compounds. The catalytic activity and selectivity of palladiumcatalysts could be modulated by changing the reaction conditions, such as the ligand, solvent,temperature, and additive.Oxidative reactions have been an important part of organic chemistry, and high selectivityand mild conditions of these processes become the current goals in modern synthetic organicchemistry. A number of oxidants have been employed in palladium catalytic systems, such asCu2+, BQ, DDQ, PhI(OAc)2, K2S2O8, which are not only expensive but also usually produceenvironmentally harmful byproducts. There is no doubt that molecular oxygen is an abundant,inexpensive, and environmentally friendly ideal oxidant with high atom economy, andharmless H2O was released after the reaction.In recent years, palladium-catalyzed reactions under molecular oxygen have attracted muchattention of chemistry researchers worldwide. These transformations generally could reducecosts, simplify products’ separation processes, enhance the atom economy, and improve theselectivities in most cases. The Pd(II)/O2catalytic systems have been employed in a widerange of laboratory and industrial research field. In our research, palladium-catalyzedreactions under molecular oxygen involving the oxidation of simple alkene substrates havebeen systematically studied based on the principle of “green chemistry”, and a variety ofnitrogen-containing organic molecules have been efficiently constructed. These novelstrategies would have broad application prospects in fields of the total synthesis of naturalproducts, pharmaceuticals, pesticides, as well as functional materials. The details aresummarized as follows:(1) Palladium-catalyzed selective oxidative cyclization based on the sequential formationof Csp2─Csp2bonds under molecular oxygen for the construction of a series of2-substitutedand2,3-disubstituted quinolines. This methodology provides an efficient strategy for the synthesis of diversely substituted quinolines, apart from Povarov reactions. Moreover, thisreaction has a broad substrate scope, and features inexpensive starting materials, mildconditions, as well as high atom efficiency.(2) Palladium-catalyzed selective oxidative cyclization of arylamines, aldehydes, andterminal olefins under molecular oxygen for the construction of a series of1,4-dihydropyridines. Preliminary exploration to synthesize unsymmetric1,4-dihydropyridineproduct was also made. Controlled experiments revealed that the (Z)-enamine was a keyintermediate of the reaction.(3) Palladium-catalyzed dehydrogenative aminohalogenation of alkenes with molecularoxygen as the sole oxidant. This protocol directly employs simple aromatic amines as thenitrogen sources, and provides highly convenient access to brominated enamine scaffoldunder mild conditions which was difficult to prepare by traditional methodologies, withunprecedented regio-and stereoselectivity as well as exceptional functional group tolerance.(4) Palladium-catalyzed oxidative coupling of aromatic primary amines and alkenesunder molecular oxygen. It provides an efficient access to (Z)-enamine compounds withexcellent regio-and stereoselectivity, and the resultant enamines could be convenientlytransformed into a series of N-containing heterocycles, such as indoles, pyrazoles, pyrroles,and1,4-dihydropyridines. The addition of LiBr was crucial to the success of thetransformation, due to its important role in avoiding the deactivation of palladium catalystarising from the strong coordination of aromatic primary amines to it.(5) Solvent-switched selectivity on palladium-catalyzed oxidative reactions involvingaromatic amines and alkenes. In the presence of30%H2O2as a co-oxidant, highly selectivedehydrogenative aminohalogenation of alkenes could be achieved with DMF as the solventunder molecular oxygen (1atm). On the other hand, highly selective bromination of aromaticamines and subsequent oxidative coupling with alkenes could be achieved with THF as thesolvent under similar conditions.更多还原