Recent Advances in Synthesis and Biological Assessment of Quinoline‐Oxygen Heterocycle Hybrids

Abstract

The exploration of hybrid molecules for targeting various diseases represents a highly promising approach which has showcased significant momentum worldwide, in the last two decades. Diversely substituted quinoline scaffolds present in naturally occurring bioactive compounds, signify their role in various biological processes and stimulated the research developments around it, for diverse therapeutic applications. With the ongoing search for suitable pharmacophores, the quinoline derivatives have emerged as versatile compounds possessing significant and broad spectrum of biological activities. Further, conjugation of quinoline with other bioactive heterocycles containing oxygen yielded hybrid organic frameworks with improved therapeutic profile leading to an emerging paradigm and tremendous growth in the contemporary drug discovery regime. The synthesis of these hybrid skeletons with high efficiency still remains the most strenuous task and a lot of research work is being performed in this direction. In the present article, we have reviewed the synthetic protocols leading to quinoline‐oxygen heterocycle hybrids and also highlighted the systematic and biological assessment of developed pharmacophores.

Click chemistry beyond metal‐catalyzed cycloaddition as a remarkable tool for green chemical synthesis of antifungal medications

“…Quinoline, an important heterocyclic scaffold found in naturally occurring bioactive compounds, belongs to the alkaloid family and is recognized as a secondary metabolite under the nitrogen‐containing natural products (Kumar, Saroha, et al., 2021). Well‐known drugs containing quinoline have displayed diverse biological activities, including antimalarial, antibacterial, anticancer, and antitubercular activities.…”

A Simple Preparative Synthesis of Isomeric 2-Chloroquinolinecarboxylic Esters

“…Step 2. Methyl 2-chloroquinoline-8-carboxylate (7), 2-chloroquinoline-8-carboxylic acid (8), methyl 2(1H)-2-oxoquinoline-8-carboxylate (9) Ester 6 (9.7 g, 0.0447 mol) was mixed with phosphorus pentachloride (12.6 g, 0.0605 mol) and phosphorus oxychloride (4.2 mL, 0.0447 mol), and stirred at 140 o C for 1 h. Water and ice were added to the reaction mass, the mixture was neutralized with 20 % NaOH to pH 5 -6 and extracted with chloroform 3×150 mL. The extract was passed through the aluminum oxide layer (6 -7 cm) and evaporated.…”

“…2-Chloroquinoline derivatives with carboxyl substituents have a wide range of activities, including antimicrobial [3], antiinflammatory [4], antitumor [5] and antiparasitic ones [6,7]. There are several methods of introducing halogen into position 2 of the quinoline molecule, but most of them relate to 2-chloroquinoline derivatives with a carboxyl/ester group in the pyridine nucleus [8,9].…”

Metal-free three-component assemblies of anilines, α-keto acids and alkyl lactates for quinoline synthesis and their anti-inflammatory activity

“…Quinoline is a fundamental heterocycle moiety and has been identified as the key structure in a large number of clinical medicines, biologically active lead compounds and natural products, as well as functional materials. 12 Traditional methods featuring carbonyl condensation, such as the Skraup, Pictet–Spengler, Doebner-von Miller, Friedlander, Pfitzinger and Combes reactions etc. , have played the main roles in the early years of quinoline synthesis.…”