Photocatalytic Oxidative C–H Thiolation: Synthesis of Benzothiazoles and Sulfenylated Indoles
作者:Andrew N. Dinh、Ashley D. Nguyen、Ernesto Millan Aceves、Samuel T. Albright、Mario R. Cedano、Diane K. Smith、Jeffrey L. Gustafson
DOI:10.1055/s-0039-1690107
日期:2019.9
sulfenylated indoles via an intermolecular reaction. Cyclic voltammetry (CV) and density functional theory studies suggest that benzothiazole formation proceeds via a mechanism that involves an electrophilic sulfur radical, while the indole sulfenylation likely proceeds via a nucleophilic sulfur radical adding into a radical cationic indole. These conditions were successfully extended to several thiobenzamides
Iron-Promoted Three-Component 2-Substituted Benzothiazole Formation via Nitroarene <i>ortho</i>-C–H Sulfuration with Elemental Sulfur
作者:Qiaoyan Xing、Yanfeng Ma、Hao Xie、Fuhong Xiao、Feng Zhang、Guo-Jun Deng
DOI:10.1021/acs.joc.8b02619
日期:2019.2.1
A three-component procedure for the preparation of 2-substituted benzothiazoles from nitroarenes, alcohols, and sulfur powder is described. The reaction showed a good functional group tolerance to provide the heterocyclic products in moderate to good yields. The sequential assembly involving nitro reduction, C–N condensation, and C–S bond formation has been realized in one pot.
Catalyst- and Supporting-Electrolyte-Free Electrosynthesis of Benzothiazoles and Thiazolopyridines in Continuous Flow
作者:Ana A. Folgueiras-Amador、Xiang-Yang Qian、Hai-Chao Xu、Thomas Wirth
DOI:10.1002/chem.201705016
日期:2018.1.9
N‐arylthioamides have been converted to the corresponding benzothiazoles in good to excellent yields and with high current efficiencies. This transformation is achieved using only electricity and laboratory grade solvent, avoiding degassing or the use of inert atmosphere. This work highlights three advantages of electrochemistry in flow, which is (i) a supporting electrolyte‐free reaction, (ii) an easy scale‐up
Exogenous Photosensitizer-, Metal-, and Base-Free Visible-Light-Promoted C–H Thiolation via Reverse Hydrogen Atom Transfer
作者:Ze-Ming Xu、Hong-Xi Li、David James Young、Da-Liang Zhu、Hai-Yan Li、Jian-Ping Lang
DOI:10.1021/acs.orglett.8b03679
日期:2019.1.4
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-tetramethylpiperidineN-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.