北京师范大学陈雪波团队报道了与功能障碍相关的扩展SET模型主导了酰胺定向远端sp3 C–H功能化。相关研究成果发表在2021年11月11日出版的国际学术期刊《美国化学会杂志》。

目前，对催化自由基反应的机理理解滞后于新型催化活化的蓬勃发展。

该文中，通过计算基于Ir络合物的光催化剂介导的酰胺定向远端sp3 C–H键烷基化范例的激发态弛豫路径，将非绝热交叉与1,5-氢原子转移(HAT)反应的速率决定步骤相结合，扩展了单电子转移(SET)模型，提供了自由基衰变动力学的控制机制。碳自由基中间体的稳定性、与后SET相关的功能障碍以及反应性三重态和闭合壳层基态之间的能量反转，被证实是通过阻断自由基抑制来提高催化效率的关键因素。

与动力学行为和动力学数据相关联的扩展的SET模型可以通过利用含有或多或少吸电子基团的光催化剂，以及综合考虑动力学溶剂效应和分子的吸电子效应来指导可见光驱动惰性键活化的设计和调控。

附：英文原文

Title: An Expanded SET Model Associated with the Functional Hindrance Dominates the Amide-Directed Distal sp3 C–H Functionalization

Author: Juanjuan Wang, Wei-Hai Fang, Ling-Bo Qu, Lin Shen, Feliu Maseras, Xuebo Chen

Issue&Volume: November 11, 2021

Abstract: The mechanistic understanding of catalytic radical reactions currently lags behind the flourishing development of new types of catalytic activation. Herein, an innovative single electron transfer (SET) model has been expanded by using the nonadiabatic crossing integrated with the rate-determining step of 1,5-hydrogen atom transfer (HAT) reaction to provide the control mechanism of radical decay dynamics through calculating excited-state relaxation paths of a paradigm example of the amide-directed distal sp3 C–H bond alkylation mediated by Ir-complex-based photocatalysts. The stability of carbon radical intermediates, the functional hindrance associated with the back SET, and the energy inversion between the reactive triplet and closed-shell ground states were verified to be key factors in improving catalytic efficiency via blocking radical inhibition. The expanded SET model associated with the dynamic behaviors and kinetic data could guide the design and manipulation of visible-light-driven inert bond activation by the utilization of photocatalysts bearing more or less electron-withdrawing groups and the comprehensive considerations of kinetic solvent effects and electron-withdrawing effects of substrates.

DOI: 10.1021/jacs.1c07983

Source: https://pubs.acs.org/doi/10.1021/jacs.1c07983