光诱导分步分态的苯型脱芳构化反应的理论研究

采用密度泛函理论(DFT)和含时密度泛函理论(TD-DFT)研究了一类重要的含有杂原子的光催化苯型脱芳反应. 研究结果表明, 该脱芳反应是一个分步分态的4+2]环加成反应, 即前一步脱芳发生在三重态, 后一步脱芳发生在单重态基态. 其中, 苯乙酮基团可被看作为光的接收装置, 吸光后使得体系从单重态经内转换和系间窜越无能垒到达三重态, 并在三重态完成质子转移生成具有反应活性的双烯, 进而引发后续的脱芳反应. 更重要的是, 通过构建势能面发现该反应具有高度的立体选择性, 与实验结果完全相符.

Theoretical Study on Photoinduced Stepwise Dearomatization of Benzenoid Arenes with Different States

A class of important dearomatization reaction of benzenoid arenes with heteroatoms via a photocatalysis were investigated with density functional theory（DFT） and time-dependent density functional theory（TD-DFT）. The results show that the dearomatization is a stepwise ［4 + 2］ cycloaddition reaction， that is， the first step occurs in the triplet state， and while the second step occurs in the singlet ground state. Here， the aetophenone group can be regarded as the receiving device of light， and after absorbing light， the system can reach the triplet state with a barrierless process via internal conversion and intersystem crossing， and subsequently complete the proton transfer in the triplet state to generate the reactive diradical， and finally trigger cause the subsequent dearomatization reaction. More importantly， by analyzing the potential energy surface， it is found that this reaction has a high stereoselectivity， which is in well agreement with the experimental results.