Synthesis and antimicrobial activity of new pyridothienopyrimidines and pyridothienotriazines

5-Acetyl-3-amino-4-aryl-6-methylthieno[2,3-b]pyridine-2-carboxamides (5a,b) were reacted with triethyl orthoformate or nitrous acid to give the corresponding pyrimidinones 6a,b and triazinones 7a,b. The reaction of 5a,b with acetic anhydride was carried out and its products were identified as a mixture of 8-acetyl-9-aryl-2,7-dimethylpyrido[3',2':4,5]thieno[3,2-d]pyrimidine-4(3H)-one(9a,b) and related 5-acetyl-4-aryl-3-biacetylamino-6-methylthieno[2,3-b]pyridine-2-carbonitrile (10a,b). Reaction of 7a with some halocompounds afforded the N-alkylated triazinones 8a-c. Chlorination of 6a,b and 9a,b with phosphorus oxychloride produced 4-chloropyrimidines 11a-d which were used as precursors for the rest of the target heterocycles. Some of the prepared compounds were tested in vitro for their antimicrobial activities.