S8 -Mediated Cyclization of 2-Aminophenols/thiophenols with Arylmethyl Chloride: Approach to Benzoxazoles and Benzothiazoles

Haifeng Gan; Dazhuang Miao; Qiang Pan; Renhe Hu; Xiaotong Li; Shiqing Han

doi:10.1002/asia.201600355

S8 -Mediated Cyclization of 2-Aminophenols/thiophenols with Arylmethyl Chloride: Approach to Benzoxazoles and Benzothiazoles

Chem Asian J. 2016 Jun 21;11(12):1770-4. doi: 10.1002/asia.201600355. Epub 2016 May 24.

Authors

Haifeng Gan¹, Dazhuang Miao¹, Qiang Pan¹, Renhe Hu¹, Xiaotong Li¹, Shiqing Han^{2

3}

Affiliations

¹ College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing, Jiangsu, 211816, P. R. China.
² College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing, Jiangsu, 211816, P. R. China. hanshiqing@njtech.edu.cn.
³ Key Laboratory of Synthetic Chemistry of Natural Substances, Shanghai Institute of Organic Chemistry, CAS, Shanghai, 200032, P. R. China. hanshiqing@njtech.edu.cn.

PMID: 27124616
DOI: 10.1002/asia.201600355

Abstract

A metal-free approach to benzazoles from arylmethyl chlorides and 2-mercaptan/2-hydroxyanilines using elemental sulfur as a traceless oxidizing agent has been developed. The reactions proceeded in good to excellent yields, exhibiting good functional groups tolerance and gram-scale ability. A key mechanistic investigation indicated that the key intermediate trisulfide 6, which was characterized by NMR, HRMS and crystal X-ray crystallography, was separated in the reaction prior to the formation of the product.

Keywords: arylmethyl chlorides; benzothiazoles; benzoxazoles; cyclization; sulfur.