铼催化脂肪酸高价碘的脱羧官能化反应研究

The presence of organic carboxylic acids in the raw petroleum oil is detrimental to the purification equipments of petroleum oil. Meanwhile, the green, renewable fatty acids hold great potential for developing new alternative energy products of petroleum oil.The key problem in the above two issues is the activation of inert C-C bonds in aliphatic carboxylic acids. In order to meet the need of new energy products, here we propose to explore the Re-catalyzed decarboxylative reactions of simple aliphatic carboxylic acids via C-C bond activation. Through the introduction of proper ligands, a series of reactive rhenium catalysts will be synthesized in order to tune their redox potentials thus enhancing the electron transfer between the rhenium catalysts and the aliphatic carboxylic acid derivatives. By merging rhenium catalysis and aliphatic carboxylic acid-derived hypervalent iodine reagents, diverse decarboxylative reactions will be developed. Also, the difunctionalization or multifunctionalization of unsaturated hydrocarbons such as olefins and alkynes will be achieved with aliphatic carboxylic acid-derived hypervalent iodine reagents via decarboxylation. Furthermore, the decarboxylative fluoroalkylation reactions of olefins and alkynes from the hypervalent iodine reagents of fluoro-containing aliphatic carboxylic acids will be investigated. In addition, the mechanism of decarboxylation and the ensuing C-C bond and C-X bond (X = heteroatom) formation promoted by rhenium will be throughly studied by means of varied experimental and computational tools. In the end, the rhenium-based decarboxylative synthetic methodology of high efficacy and selectivity are to be established.

发展简单脂肪酸中惰性C-C键活化的新方法对于解决石油原油中去除有机酸性物质难题，利用可再生的长链脂肪酸制备石油替代能源产品，以及探索基础研究中惰性化学键的切断与重组等科学问题都具有重要的意义。本项目拟面向国家在上述能源方面的战略需求，针对其中存在的关键科学问题-脂肪酸中惰性C-C键的活化，发展铼催化的普通脂肪酸的新型脱羧官能化反应。通过配体的引入，合成一系列高活性的铼催化剂，并调控铼催化剂的氧化还原电位，提高其与脂肪酸衍生物的电子转移效率；通过采用"底物活化"和"催化剂活化"相结合的双重活化策略，将铼催化体系与脂肪酸高价碘试剂进行有机的融合，发展普通脂肪酸的脱羧单官能化反应、对不饱和烃的脱羧双及多官能化反应、以及含氟脂肪酸的脱羧氟烷基化反应等；同时，通过各种手段对普通脂肪酸的脱羧反应机理进行深入而系统的研究，最终发展具有铼金属特色的普通脂肪酸脱羧反应新体系。

自然界动植物中广泛存在的油脂原料具有来源广泛、廉价无毒、环境友好等优点；同时，这些动植物原材料具有绿色可再生的特性，因而有可能成为未来新一代可再生能源产品。利用油脂化合物的关键科学问题是如何实现脂肪酸中惰性C-C键的活化。发展脂肪酸中惰性C-C键活化的新策略、新体系和新方法对于探索基础研究中惰性化学键的切断与重组等核心科学问题具有重要的意义。本项目针对脂肪酸中惰性C-C键活化的关键科学问题，发展脂肪酸及其衍生物的新型脱羧反应。具体开展了铼催化的脂肪酸高价碘的脱羧官能化反应研究，采用“底物活化”和“催化剂活化”相结合的双重活化策略实现了温和条件下的普通脂肪酸和含氟脂肪酸的脱羧反应。机理上通过自由基脱羧的途径生成烷基自由基，然后和一系列有机底物反应构建新的C-C键以及C-X键（X = 杂原子）等，发展高效的绿色有机合成新反应，新方法。