An easy and fast one-pot preparation of 2-thiomethyl and 2-thioacyl benzothiazoles, benzoxazoles, and benzimidazoles

Quaternary 2-thiomethylbenzazoles are important class of intermediates involved in the synthesis of symmetric and asymmetric monomethine cyanine dyes. In addition to, 2methylmercaptobenzothiazole, and 2methylmercaptobenzoxazole derivatives represent an essential group of compounds for the synthesis of cyanine dyes [1–3]. S-Alkylated heterocyclic derivatives are known as key compounds, finding application in copper and copper alloys protection against corrosion [4–6]. Thiocarboxylic acid esters (2-thioacyl derivatives) can be used in various chemical transformations, such as asymmetric aldol reactions [7], and as cephalosporin derivatives [8]. Thioethers play an important role in the development of thiol drugs, especially in masking the unpleasant odor and taste of the native thiol [9]. Recently we have published two methods as an environmentally benign ways the former of which involves the synthesis of substituted 2thiobenzothiazoles, 2-thiobenzoxazoles, 2thiobenzimidazoles, and 1,3-oxazolopyridine-2thiols [10], as well as an easy and fast ultrasonic selective S-alkylation of hetaryl thiols proceeding at room temperature as presented in the latter publication [11]. Herein we report that those two methods mentioned above can be joined together in a novel synthetic procedure, for an easy and fast one-pot preparation of 2-thiomethylbenzothiazoles, 2thiomethylbenzoxazoles, 2-thiomethylbenzimidazoles or 2-thioacylbenzothiazoles, 2thioacylbenzoxazoles and 2thioacylbenzimidazoles. EXPERIMENTAL