Exogenous Photosensitizer‑, Metal‑, and Base-Free Visible-Light-Promoted C–H Thiolation via Reverse Hydrogen Atom Transfer

Visible-light-driven, intramolecular C­(sp2)–H thiolation has been achieved without addition of a photosensitizer, metal catalyst, or base. This reaction induces the cyclization of thiobenzanilides to benzothiazoles. The substrate absorbs visible light, and its excited state undergoes a reverse hydr...

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Bibliographic Details
Published in:Organic letters 2019-01, Vol.21 (1), p.237-241
Main Authors: Xu, Ze-Ming, Li, Hong-Xi, Young, David James, Zhu, Da-Liang, Li, Hai-Yan, Lang, Jian-Ping
Format: Article
Language:English
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Summary:Visible-light-driven, intramolecular C­(sp2)–H thiolation has been achieved without addition of a photosensitizer, metal catalyst, or base. This reaction induces the cyclization of thiobenzanilides to benzothiazoles. The substrate absorbs visible light, and its excited state undergoes a reverse hydrogen-atom transfer (RHAT) with 2,2,6,6-tetramethylpiperidine N-oxyl to form a sulfur radical. The addition of the sulfur radical to the benzene ring gives an aryl radical, which then rearomatizes to benzothiazole via RHAT.
ISSN:1523-7060
1523-7052
DOI:10.1021/acs.orglett.8b03679