Synthesis, characterization, and antitumor activity of some novel S-functionalized benzo[d]thiazole-2-thiol derivatives; regioselective coupling to the –SH group

Abstract

Abstract Several 2-substituted sulfanyl benzo[d]thiazoles were regioselectively synthesized by the reaction of benzo[d]thiazole-2-thiol (1a) with a variety of reagents under different basic conditions. Some 2-(2,3-disubstituted propyl sulfanyl)benzo[d]thiazoles were obtained from 2-(allylthio)benzo[d]thiazole, which was prepared by the allylation of 1a with allyl bromide in the presence of sodium hydride in dry N,N-dimethylformamide. Reaction of 1a with various pyrazolyl-quinoxaline derivatives was also investigated. Better yields and shorter reaction time were achieved for the synthesis of some derivatives by using ultrasound irradiation. The structural elucidation of all compounds was based on both analytical and spectroscopic data. The newly synthesized compounds were tested in vitro for their antitumor activity against Ehrlich ascites carcinoma (EAC) cells grown in albino mice. Doxorubicin was used as a standard antitumor antibiotic, and some compounds showed half maximal inhibitory concentration (IC50) in the range 40–68 μg mL−1.