Visible‐Light‐Mediated Activation of Remote C(sp<sup>3</sup>)−H Bonds by Carbon‐Centered Biradical via Intramolecular 1,5‐ or 1,6‐Hydrogen Atom Transfer
Xin-Tao Gu, Jiahao Shen, Ziyu Xu, Jiaxin Liu, Jiaxin Liu, Min Shi, Min Shi, Yin Wei
Abstract
In this study, we introduce a novel intramolecular hydrogen atom transfer (HAT) reaction that efficiently yields azetidine, oxetane, and indoline derivatives through a mechanism resembling the carbon analogue of the Norrish-Yang reaction. This process is facilitated by excited triplet-state carbon-centered biradicals, enabling the 1,5-HAT reaction by suppressing the critical 1,4-biradical intermediates from undergoing the Norrish Type II cleavage reaction, and pioneering unprecedented 1,6-HAT reactions initiated by excited triplet-state alkenes. We demonstrate the synthetic utility and compatibility of this method across various functional groups, validated through scope evaluation, large-scale synthesis, and derivatization. Our findings are supported by control experiments, deuterium labeling, kinetic studies, cyclic voltammetry, Stern-Volmer experiments, and density functional theory (DFT) calculations.