Synthesis and cardiotonic activity of certain imidazo[2,1-b]-1,3,4-thiadiazole derivatives

A series of 5-imino-2-methyl-4-(4'-substituted phenacyl)-1,3, 4-thiadiazole derivatives 3-5 have been synthesized and further used to prepare a series of 2-methyl-6-(4'-substituted phenyl)imidazo[2, 1-b]-1,3,4-thiadiazoles 6-8 and 5-substituted-2-methyl-6-(4'-substituted phenyl) imidazo[2, 1-b]-1,3, 4-thiadiazoles 9-18. All of newly prepared imidazothiadiazole compounds were screened for their cardiotonic activity in isolated guinea pig atria. The detailed synthesis, spectroscopic and biological data are reported.