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Regioselective Transition‐Metal‐Free Synthesis of Diverse Benzothiazoles by Thermally Induced Cyclization of ortho ‐Halobenzanilides
Author(s) -
Jang Keun Sam,
Shin Dong Seok,
Song Ho Rim,
Lee Byoung Se,
Chi Dae Yoon
Publication year - 2017
Publication title -
chemistryselect
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.437
H-Index - 34
ISSN - 2365-6549
DOI - 10.1002/slct.201701130
Subject(s) - regioselectivity , benzothiazole , intramolecular force , substituent , chemistry , combinatorial chemistry , cascade reaction , bromine , molecule , reaction conditions , organic chemistry , catalysis
The highly regioselective and efficient synthesis of diverse substituted‐benzothiazoles, including heterocyclic units and amino groups, was achieved in moderate to high yields from ortho ‐bromothiobenzanilides, ortho ‐bromoarylthioureas, ortho ‐bromobenzanilides, and ortho ‐dibromobenzanilides, regardless of the electron density and substituted positions, via the prevalent carbon‐sulfur bond formation by thermally induced intramolecular cyclization reaction without using any metal sources or other additives. Polysubstituted‐benzothiazoles, particularly 2,4‐, 2,6‐disubstituted, and 2,4,6‐trisubstituted benzothiazoles, could be efficiently synthesized by a facile cascade reaction from appropriate ortho ‐bromobenzanilides under general thiolation conditions. This benign reaction represents a straightforward and practical approach toward diverse substituted‐benzothiazoles. In addition, the remaining bromine substituent of the resulting products was further utilized as a functional handle for the additional diversification and exploited as a complementary solution for the adjustment of harsh reaction condition. This methodology not only allows for the elaboration of benzothiazole molecules, but also provides a new valuable synthetic tool for a range of pharmaceutical applications.