Microwave-assisted synthesis of 2-aryl(hetaryl)-5-phenylamino-1,3,4-thiadiazoles from 5-substituted tetrazoles

Abstract

In the recent years 2-aryl-5-arylamino-1,3,4-thiadiazoles have attracted considerable attention due to their intrinsic high biological activity [1]. Compounds of the 2-aryl-5-arylamino-1,3,4-thiadiazole series were found to exhibit antimicrobial [2], antituberculous [3], and antiphlogistic properties [4], as well as to inhibit development of some cancer diseases [5]. However, the lack of convenient methods for the preparation of 2,5-disubstituted 1,3,4-thiadiazoles strongly restricts their potential application in medical practice. Known and widely used methods of synthesis of 2,5-disubstituted 1,3,4-thiadiazoles often include a number of steps and are insufficiently effective [1, 6]. On the other hand, as early as 1961 Huisgen et al. [7] reported a simple one-step procedure for the synthesis of 2-phenyl-5-phenylamino-1,3,4-thiadiazole from 5-phenyl-1H-tetrazole and phenyl isothiocyanate.