Synthesis of Some Novel Quinoline-3-carboxylic Acids and Pyrimidoquinoline Derivatives as Potential Antimicrobial Agents

3-Cyano-8-methyl-2-oxo-1,4-disubstituted-1,2,5,6,7,8-hexahydroquinolines: synthesis and biological evaluation as antimicrobial and cytotoxic agents

“…In a similar fashion, warming the starting compounds 4-6 with acetic anhydride in the presence of anhydrous sodium acetate furnished the N-acetyl derivatives 12-14. In their turn, when the latter compounds were reacted with hydrazine hydrate, the targeted 5,6,7,8-tetrahydro [1,2,4] triazolo[3,4-a]quinolines 15-17 were successfully obtained. In Scheme 2, the same hexahydroquinolines 4-6 were utilized as key intermediates for the synthesis of the target compounds 18-32.…”

“…Whereas, acetylation (12)(13)(14) led to a slight improvement in the antimicrobial spectrum, especially 13 (R = Cl), which showed broad antibacterial in addition to some antifungal activities. However, cyclization of the latter N-acetyl compounds into the tricyclic [1,2,4]triazolo[3,4-a]quinolines 15-17 resulted in a dramatic reduction in the antimicrobial spectrum and potential. On the other hand, introducing a benzenesulfonyl moiety at position-1 gave rise to three active compounds 18-20, among which the chloro derivative 19 showed equipotent activity to ampicillin against E. coli and 50% of its activity against S. aureus, B. subtilis and P.aeruginosa, together with an appreciable antifungal activity against C. albicans.…”

“…In recent years, pyridines and some derived fused-ring systems such as quinolines have attracted much attention as versatile chemotherapeutic agents owing to their reported potential antimicrobial activity [4][5][6] , in addition to various antineoplastic 7 , antiproliferative 8 , and cytotoxic 9 potentials. Furthermore, particular interest has been given to cyanopyridine derivatives as anticancer and antiviral 10 agents.…”

“…The target compounds were designed to encounter various pharmacophores and functionalities at positin-1 that are believed to be responsible for the biological significance of some relevant antimicrobial and/or anticancer agents such as the formyl, acetyl, nitroso, benzenesulfonyl, thiocarbamoyl and alkyl groups. Moreover, it was considered worthwhile to utilize the N-acetyl derivatives as precursors for the synthesis of the tricyclic fused-ring system tetrahydro [1,2,4]triazolo [4,3-a]quinoline as an interesting structural variation, hoping to improve the anticipated chemotherapeutic activities.…”

Facile Synthesis of 5, 6, 7, 8-Tetrahydropyrimido [4, 5-b]-quinoline Derivatives

“…Pyrimidoquinolines are important compounds because of their biological properties, which are known to depend mainly on the nature and position of substituents, and include antimalarial [1], anticancer [2], antimicrobial [3,4], and anti-inflammatory activities [5,6]. Recently there has also been considerable interest in the synthesis and chemistry of tetrahydroquinolines and their fused derivatives [7][8][9][10][11].…”