Chem. Pharm. Bull. 55(4) 557—560 (2007)

20th century. With the discovery of antibiotics people were convinced that infectious diseases might some day be wiped out. Diseases that were once life threatening, such as pneumonia, had become curable. The success of antibiotics in therapy related fields has made them one of the most important products of the drug industry today. However, the emergence of super bugs ie. bacteria that resists the effects of the most powerful antibiotics are posing a great challenge to the field of medicines. Thus scientists are working to find new ways to defeat bacteria that are increasingly resistant to the antibiotics already available. Literature survey shows that several fused pyrimidines and pyridines like triazolo quinazolines and triazoloquinolines have shown good antibacterial activity. Further condensed triazoles have been reported to possess large number of pharmacological activities like fungicidal, pesticidal etc. Thienopyrimidines has been reported to exhibit antimicrobial activities too. Based on the concept of bioisosterism and all the above observations have led us to the proposal to incorporate triazole ring system into thienopyrimidines leading to the synthesis of novel class of triazolothienopyrimidines as bioisosteres of triazoloquinolines and quinazolines and to test for its efficacy as antibacterial agents. Herewith we are reporting the synthesis of some novel 5-substiuted-1,2,4-triazolo[4,3-c]8,9,10,11,12-pentahydrocyclohepta/8,9,10-trihydrocyclopenta[b]thieno[3,2-e]pyrimidin-3-thiones as possible antibacterial agents.