Photoredox Catalyzed Remote C(sp3)–H Trifluoromethylation

我们计划开发一个光氧化还原催化的三氟甲基化远程未激活的C（sp3）-H键分子内指导的酰胺基团。我们提出，这种催化通过金属基光催化剂氧化原位形成的酰胺基阴离子进行，该金属基光催化剂快速进行1，5-氢原子转移。所得的碳中心自由基可以通过另一种过渡金属催化剂经由自由基交叉偶联与三氟甲基自由基偶联。优化研究将包括筛选三氟甲基化试剂，使用的溶剂和碱，以及筛选的光催化剂和交叉偶联催化剂。我们的最终计划是扩展这种方法对分子间的三氟甲基化的二级C（sp3）-H键在简单的烷烃分子间的氢抽象。此外，未活化的C（sp3）-H键的重链也会引起我们的兴趣。循环伏安法和Stern-Vollmer实验等分析方法有助于阐明这种催化作用的反应机理。

We plan to develop a photoredox-catalyzed trifluoromethylation of remote unactivated C(sp3)–H bonds intramolecularly directed by an amide group. We propose that this catalysis proceeds via oxidation of an in-situ-formed amidyl anion by a metal-based photocatalyst, which undergoes quickly a 1,5-hydrogen atom transfer. The resulted carbon-centered radical can be coupled with a trifluoromethyl radical by another transition metal catalyst via radical cross-coupling. Optimization studies will include screenings of trifluoromethylating reagents, used solvents and bases, as well as screenings of the photocatalysts and cross-coupling catalysts. Our final plans are to expand this methodology toward intermolecular trifluoromethylation of secondary C(sp3)–H bonds in simple alkanes by an intermolecular hydrogen abstraction. Moreover, the fluorination of unactivated C(sp3)–H bonds would be of similar interest to us. Analytical methods like cyclic voltammetry and Stern-Vollmer experiments should help elucidating the reaction mechanism of this catalysis.