Visible-Light-Induced Alkoxyl Radicals Enable α-C(sp3)-H Bond Allylation

• Published in: iScience Vol. 23; no. 1; p. 100755
• Main Authors: Zhang, Jing, Liu, Dan, Liu, Song, Ge, Yuanyuan, Lan, Yu, Chen, Yiyun
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 24.01.2020; Elsevier
• Subjects: Organic Chemistry; Organic Reaction; Physical Organic Chemistry; Organic Reaction; Physical Organic Chemistry; Organic Chemistry
• ISSN: 2589-0042; 2589-0042
• DOI: 10.1016/j.isci.2019.100755

The alkoxyl radical is an essential reactive intermediate in mechanistic studies and organic synthesis with hydrogen atom transfer (HAT) reactivity. However, compared with intramolecular 1,5-HAT or intermolecular HAT of alkoxyl radicals, the intramolecular 1,2-HAT reactivity has been limited to theoretical studies and rarely synthetically utilized. Here we report the first selective 1,2-HAT of alkoxyl radicals for α-C(sp3)-H bond allylation of α-carbonyl, α-cyano, α-trifluoromethyl, and benzylic N-alkoxylphthalimides. The mechanistic probing experiments, electron paramagnetic resonance (EPR) studies, and density functional theory (DFT) calculations confirmed the 1,2-HAT reactivity of alkoxyl radicals, and the use of protic solvents lowered the activation energy by up to 10.4 kcal/mol to facilitate the α-C(sp3)-H allylation reaction. [Display omitted] •1,2-Hydrogen atom transfer (HAT) of alkoxyl radical enables α-C(sp3)-H allylation•α-Carbonyl, α-cyano, α-trifluoromethyl, and benzylic C(sp3)-H bonds are applicable•Mechanistic and electron paramagnetic resonance (EPR) studies confirmed 1,2-HAT•DFT calculations explained the methanol acceleration of alkoxyl radical 1,2-HAT Organic Chemistry; Organic Reaction; Physical Organic Chemistry