Synthesis and preliminary antimicrobial activity of new pyrimido[4,5-b]-quinoline and pyrido[2,3-d]pyrimidine

4-Chloro-2-methylthio-benzo[h]pyrimido[4,5-b]quinoline (5) and pyrido[2,3-d]-pyrimidine (12), were easily prepared from the cyclo-condensation of alpha, beta-unsaturated ketones and 6-aminothiouracil. Compound 5 reacted with different amines to give 8-aryl-amino- (6,7), 2,4-dihydrazino-pyrimido[4,5-b]quinoline (9). Compound 7 was converted into benzo[h]-12,13-dihydrobenzo[a]-pyrimido[3',2':1,6]pyrimido[4,5-b]-quinoline (8) with a new ring system. The 2,4-dihydrazino-reacted with formic acid to afford benzo[h]-s-triazolo[4',3':1,6]-s-triazolo[3'',4'':2,3]pyrimido[4,5-a]quinoline (10) with a new ring system. Also, reaction of (12) with bromomalononitrile gave 3-amino-thiazolo[4,5-a]pyrido[2,3-d]pyrimidine-2-carbonitrile (13). Compound 13 reacted with formic acid, urea, thiourea, formamide to affording the pyrimido[4',5':-4,5]thiazolo[3,2-a]pyrido[2,3-d]pyrimidin-12-one (14, 15, 16a,b, 21) and reacted with carbon disulfide to give pyrido[2 '',3 '':4',5']pyrimido[2',1':2,3]thiazolo[4,5-d][1,3]-thiazine (17). Some of the synthesized derivatives exhibited, upon screening, antibacterial and antifungal activities.