Azomethine ylide-formation from N-phthaloylglycine by photoinduced decarboxylation:A theoretical study

在这个工作，我们报导 N-phthaloylglycine 的 photodecarboxylation 的机制的第一 CASPT2//CASSCF 研究。费用转移使州的 SCT (1*) 激动开始在 266 nm 在照耀之上被占据。由于到最低激动的汗衫状态 SCT-N (1*) 的快内部变换，这个状态为质子转移成为一个有利先锋状态，它触发去碳酸基。实际上，激动的州的 intramolecular 质子转移(ESIPT ) 和去碳酸基过程以一个异步的一致方法继续。ESIPT 过程处于 SCT-N (1*) 状态被完成，但是 CO2 分子最后经由 SCT/S0 圆锥形的交叉处于扎根的状态被形成。Azomethine ylide 与 CO2 作为建筑群处于扎根的状态被形成。15 kcal/mol 的一个障碍显示 azomethine ylide 处于扎根的状态是稳定的，它与试验性的调查结果一致。这个工作由 N-phthaloylglycine 的 photoreaction 关于 azomethine ylide 的形成提供机械学的细节。

In this work, we report the first CASPT2//CASSCF study of the mechanism of the photodecarboxylation of N-phthaloylglycine. The charge transfer excited state S CT （ 1∏∏＊） is initially populated upon irradiation at 266 nm. As a result of a fast internal conversion to the lowest excited singlet state S CT-N （ 1∏∏＊）, this state becomes a favorable precursor state for proton transfer, which triggers decarboxylation. Actually, the excited state intramolecular proton transfer （ESIPT） and decarboxylation processes proceed in an asynchronous concerted way. The ESIPT process is accomplished in the S CT-N （ 1∏∏＊） state, but the CO 2 molecule is finally formed in the ground state via the S CT /S 0 conical intersection. Azomethine ylide is formed in the ground state as a complex with CO 2 . A barrier of ~15 kcal/mol indicates that azomethine ylide is stable in the ground state, which is consistent with the experimental findings. This work provides mechanistic details about the formation of azomethine ylide by photoreaction of N-phthaloylglycine.