Direct benzylation reactions from benzyl halides enabled by transition-metal-free photocatalysis

An SN2-based photochemical strategy using dithiocarbamate anion as catalyst was developed for the activation of benzyl halides, which are extremely challenging to be applied as radical precursors in visible light photocatalysis. With this transition-metal-free and oxidant-free protocol, the benzylat...

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Bibliographic Details
Published in:Chinese chemical letters 2022-12, Vol.33 (12), p.5074-5079
Main Authors: Xiang, Panjie, Sun, Kai, Wang, Shuang, Chen, Xiaolan, Qu, Lingbo, Yu, Bing
Format: Article
Language:English
Subjects:
Benzylation
N-Heterocyclics
Photocatalysis
Radical reaction
Transition-metal-free
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Summary:An SN2-based photochemical strategy using dithiocarbamate anion as catalyst was developed for the activation of benzyl halides, which are extremely challenging to be applied as radical precursors in visible light photocatalysis. With this transition-metal-free and oxidant-free protocol, the benzylation (or cyanomethylation) of various heterocycles including quinoxalin-2(1H)-ones, coumarin, 2-phenyl-2H-indazole, 1-methyl-5-phenylpyrazin-2(1H)-one, 1-(fluoromethyl)cinnolin-4(1H)-one, and 2,4-dibenzyl-1,2,4-triazine-3,5(2H,4H)‑dione could be realized (46 examples, up to 98% yield). Importantly, some biologically relevant 3-benzylquinoxalin-2(1H)-ones were also be synthesized under mild conditions. An SN2-based photochemical strategy using dithiocarbamate anion as catalyst was developed for the activation of benzyl halides, and the benzylation (or cyanomethylation) of various heterocycles could be realized. [Display omitted]
ISSN:1001-8417
1878-5964
DOI:10.1016/j.cclet.2022.03.096