2-Amino-4,5-dimethylbenzothiazole is a reagent used in the synthesis of a series of substituted pyrimido[2,1-b]benzothiazoles which exhibit antimicrobial activity. 2-Amino-4,5-dimethylbenzothiazole can also be used as a potential modulator of SKCa, IKCa, and BKCa channels.