新的可见光催化体系下酚类化合物的偶联反应研究

The development of novel visible-light photocatalytic systems and reactions is very important from the point of view of a clean and energy efficient demand for organic transformations. In this project, metal nanoparticles supported on organic materials will be developed as photocatalysts and hydrogen-evolution catalysts to avoid the influence of sacrificial oxidants on the couplings of phenols and improve the yields and chemoselectivities of the reactions. In addition, with the aid of NAD(P)+ models supported on magnetic nanoparticles, the in-situ storage and subsequent application of the electrons and protons generated during the couplings of phenols will be studied by mimicking the hydride transfer reaction in organism. We also plan to investigate the relationship between structures of the phenol radicals and their reactivities under visible-light photocatalytic conditions, and control the cross-coupling of phenol radicals with other radicals by regulating their stabilities. In brief, this project is designed to solve the problems raised from the traditional thermal coupling reactions of natural polyphenols, such as unfitting the principles of green chemistry, the complexities of coupling products and so on. As a result, a series of novel, high efficient and renewable visible-light photocatalytic systems are expected to be developed in this project.

发展新的可见光催化体系和反应类型，对实现洁净、节能的有机反应至关重要。本项目拟开发负载金属纳米颗粒的有机材料作为光催化-产氢催化剂，摒除牺牲性氧化剂对反应的干扰，有效提高可见光催化下酚类化合物偶联反应的产率和化学选择性；拟通过模拟生物体中的氢转移反应和使用固载于磁性纳米颗粒的NAD(P)+模型化合物，在实现可见光催化下酚类化合物偶联反应的同时将体系产生的电子和质子原位贮存并后续应用；拟研究可见光催化条件下酚类自由基共振结构和反应活性之间的关系，并利用电子受体产生的稳定自由基，实现它们和酚类自由基的交叉偶联反应。总之，我们计划通过本项目的执行，解决传统的天然酚类化合物偶联反应不符合绿色化学要求、反应产物复杂等问题，并实现多种新颖、高效、可重复使用的可见光催化体系的构建。

本项目致力于发展新颖、洁净、高效的可见光催化酚类化合物偶联反应。通过研究可见光催化条件下酚类自由基共振结构和反应活性之间的关系，利用金属配位、酸度调节、溶剂控制等手段，实现了多例酚类化合物之间的交叉偶联反应，构筑了2-芳基苯并吗啉、3-芳基苯并吗啉、苯并1,4-二氧六环、2-芳基苯并二氢呋喃、2,3-二氢-1H-茚等多种天然产物骨架，解决了传统天然酚类化合物偶联反应不符合绿色化学要求、反应产物复杂等问题。此外，在项目周期内，我们研究了多种酰基α碳自由基的活性，实现了一系列可见光催化下自由基的二聚反应、交叉偶联反应以及加成反应。项目也在发展廉价高效的可见光驱使需氧氧化反应、铜催化的光化学转化等领域取得了很好的研究进展。总之，本项目取得的研究成果，对解决自由基交叉偶联的化学选择性、设计符合可持续发展要求的可见光催化体系有积极的参考价值。