Synthesis and Preliminary Antimicrobial Activity of New Pyrimido[4,5-b]-quinoline and Pyrido[2,3-d]pyrimidine

Abstract

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 α,β -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-b]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.

Keywords:

• 4-Chlorobenzo[h]pyrimido[4,5-b]quinoline
• benzo[h]-12,13-dihydro-benzo [a]pyrimido[3′,2′:1,6]pyrimido[4,5-b]quinoline
• benzo[h]-s-triazolo-[4′,3′:1,6]-s-triazolo [3″,4″:2,3]pyrimido[4,5-b]quinoline

Notes

*C = Concentration of the sample in mg/ml; + = Inhibition values = 0.1–0.5 cm beyond control; ++ = Inhibition values = 0.6–1.0 cm beyond control; and +++ = Inhibition values = 1.1–1.5 cm beyond control.