A new series of amino acid derivatives of quinolines was synthesized through the hydrolysis of amino acid methyl esters of quinoline carboxamides with alkali hydroxide. The compounds were purified on silica gel by column chromatography and further characterized by TLC, NMR and ESI-TOF mass spectrometry. All compounds were screened for in vitro antimicrobial activity against different bacterial strains using the microdilution method. Most of the synthesized amino acid-quinolines show more potent or equipotent inhibitory action against the tested bacteria than their correspond esters. In addition, many of them exhibit fluorescent properties and could possibly be utilized as fluorophores. Molecular docking and simulation studies of the compounds at putative bacterial target enzymes suggest that the antimicrobial potency of these synthesized analogues could be due to enzyme inhibition via their favorable binding at the fluoroquinolone binding site at the GyrA subunit of DNA gyrase and/or the ParC subunit of topoisomerase-IV.

This study reports the synthesis of 2-thioxo-1,3-dithiol-carboxamides (TDTCAs) under mild conditions at room temperature using HBTU as a coupling agent, which significantly improved amide bond formation. The synthesized compounds were characterized using several analytical techniques, including ¹H and ¹³C NMR spectroscopy, and HRMS, confirming their intended structures and structural integrity. A DFT computational study at the B3LYP/6-31G(d,p) level was conducted on the four synthesized compounds to compare their electronic properties and molecular structures. The results showed that these compounds demonstrated antispasmodic effects on jejunum contractions. Molecular docking revealed that compounds c and d displayed the highest docking scores on potassium and voltage-gated calcium channels and adrenergic receptors. In summary, compounds c and d exhibit antispasmodic effects, potentially blocking alpha-adrenergic receptors and calcium channels, thus providing a scientific basis for their potential use in treating gastrointestinal disorders.

The chemistry of 2-quinolones derivatives has received more attention in organic chemistry and medicinal chemistry. Moreover, several advancements in the application of this family of compounds are considered to be of great utility. In recent years, a variety of new, effective, and novel synthetic approaches (including green chemistry, catalyzed and microwave-assisted synthesis) have been discovered and developed for the designing of safe and non-toxic 2-quinolone-based scaffolds to investigate their antibacterial activities. This review summarizes the results of the literature on the synthesis strategies of 2-quinolones derivatives and their reactivity, as well as their antibacterial evaluations against different bacteria strains.

Ten new quinoline-carboxamides have been synthesized using the coupling reaction between 2-oxo-1,2-dihydroquinoline-4-carboxylic acid as a substrate and five different amino ester at room temperature with basic media (triethylamine). The products were obtained with a good yield ranging from 60 to 80 % and were structurally characterized by 1H and 13C NMR spectroscopy and mass spectrometry. The antibacterial activities of the synthesized compounds have been evaluated against 9 strains of bacteria and compared to references (erythromycin, ofloxacin, ticarcillin, oxacillin, ampicillin, norfloxacin, ceftazidim, cefotaxim). The results showed that the majority of carboxamides-quinoline ester groups present a larger inhibition diameters than those of the antibiotics references. The highest antibacterial activity in vitro against the Enterococcus feacalis has been revealed for compound 1a (methyl 2-oxo-1.2-dihydroquinoline-4-yl-L-alaninate).

The substituted cyclopentadienyl ring in the title molecule, [Fe(C₅H₅)(C₁₈H₁₃ClN)], is nearly coplanar with the phenyl-1-(4-chlorophenyl)methanimine substituent, with dihedral angles between the planes of the phenylene ring and the Cp and 4-(chlorophenyl)methanimine units of 7.87 (19) and 9.23 (10)°, respectively. The unsubstituted cyclopentadienyl ring is rotationally disordered, the occupancy ratio for the two orientations refined to a 0.666 (7)/0.334 (7) ratio. In the crystal, the molecules pack in `bilayers' parallel to the ab plane with the ferrocenyl groups on the outer faces and the substituents directed towards the regions between them. The ferrocenyl groups are linked by C—H...π(ring) interactions. A Hirshfeld surface analysis of the crystal structure indicates that the most important contributions for the crystal packing are from H...H (46.1%), H...C/C... H (35.4%) and H...Cl/Cl...H (13.8%) interactions. Thus C—H...π(ring) and van der Waals interactions are the dominant interactions in the crystal packing.