Synthesis of Some Novel Pyridazine, Thieno(2,3-c)pyridazine, and Pyrimidothienopyridazine Derivatives having a Sulfonamido Moieties as Potential Antimicrobial Agents

Cyano-5,6-dimethylpyridazin-3-ylthio)-N-(4-substituted-sulfamoyl)phenyl)acetamides 4a-c, were prepared by reaction of 4-Cyano-5,6-dimethylpyridazine-3(2H)-thione 3 with N-Chloroacetylsulfanilamides in the presence of sodium acetate, which were cyclized with piperidine to afford the corresponding thieno(2,3-c)pyridazines derivatives 5a-c. Cyclization of compounds 5a-c with triethyl orthoformate furnished the novel pyrimidothienopyridazines7a-c. Also, refluxing of compound 5a with carbon disulfide in pyridine afforded the corresponding pyrimido('4,'5:4,5)thieno(2,3-c)pyridazine derivative 8. S-alkylated products 9, 10 were obtained by the reaction of compound 8 with some halocompounds in ethanol in the presence of base. The antimicrobial activity for all the synthesized compounds was screened.