S-arylation of 2-mercaptobenzazoles: a comprehensive review

In recent years 2-arylthio-benzazoles (benzothiazoles, benzoxazoles, and benzimidazoles) have attracted more and more attention due to their diverse biological and pharmacological properties. Consequently, great efforts have been devoted to exploiting efficient strategies towards the synthesis of titled compounds. Among the different methods reported for the synthesis of 2-arylthio-benzazoles, the most general and applicable one consists of the C-S cross-coupling of corresponding 2-mercaptobenzazoles with various electrophilic coupling partners. This protocol has advantages of the easily accessible starting materials, satisfactory yield of products, broad substrate scope, and high generality which makes it a useful and attractive method for the construction of various 2-arylthio-benzazoles. In this review, we highlight the significant advances achieved in this field from 1987 to 2017, with special emphasis on the mechanistic aspects of the reactions. [GRAPHICS] .