氮杂环卡宾（NHC）催化自由基交叉偶联反应研究

氮杂环卡宾与醛作用后产生Breslow中间体,能够使醛的极性发生反转，构建一些难以形成的化学键。因此，在有机合成领域具有重要的应用。该类催化过程主要涉及双电子反应途径，而Breslow中间体作为单电子给体研究相对较少。目前，氮杂环卡宾催化自由基交叉偶联反应存在一些弊端：1）Breslow中间体只作为催化剂，自身并不参与到产物的生成；2）远程导向自由基交叉偶联反应从未涉足。因此本项目拟理性设计以氮原子为骨架的一系列单电子受体物种，通过单电子氧化途径分别实现多组分烯烃的胺羰基化反应以及远程导向羰基官能团化。具体研究内容是亲电含氮硝化试剂或胺化试剂氧化Breslow中间体生成含氮自由基然后参与到自由基的交叉偶联反应以及氮-卤代胺氧化Breslow中间体，通过1，5-氢迁移实现远程碳氢羰基化反应。本项目的研究与完善，将为羰基化合物的精准构建提供一种新策略。

The Breslow intermediates, generated by reacting N-Heterocyclic carbene (NHC) organocatalysts with aldehydes, show characteristic properties to harness umpolung reactivity, and have been recognized as a powerful tool for organic synthesis. NHC catalysis involving two-electron reactions pathway has been extensively studied, while Breslow intermediates as single-electron donors remain underdeveloped. Currently, NHC-catalyzed radical cross-coupling reactions have gained increasing attention, but these reactions are limited by the following challenges:1) Breslow intermediates only serve as catalysts and do not participate in the reactions as coupling partners; 2) The remotely directed radical cross-coupling reactions have never been explored. Therefore, this project aims to rationally design a series of single-electron acceptors based on nitrogen atoms as the skeleton and to realize the three-component amine carbonylation of olefins and the remote-directed carbonyl functionalization via a single-electron oxidation pathway. The proposed research aims are to develop 1) electrophilic nitrogen-containing nitration reagents or amination reagents which can allow for the oxidation of Breslow intermediate to generate nitrogen-containing radicals and then participate in the cross-coupling reactions. 2) The remote C-H carbonyl functionalization could successfully achieve through 1,5-hydrogen migration in the presence of nitrogen-halogenated amines and Breslow intermediates. The research and improvement of this project will provide new strategies for the precise construction of carbonyl compounds.