A review on synthetic investigation for quinoline- recent green approaches

Tandem Protocol of Hexahydroquinoline Synthesis Using [H2-DABCO][HSO4]2 Ionic Liquid as a Green Catalyst at Room Temperature

“…DABCO is a cagelike tertiary amine having weak alkalinity. This cagelike structure increases the energy barrier of nitrogen inversion so the lone pair is localized and makes DABCO more susceptible toward quaternization and ionic liquid preparation and further applied in organic reactions. − Regarding the abovementioned notable properties of 1,4-DHP derivatives, their synthetic methods have been investigated in various environmental conditions. − However, most of the research studies have been done on the synthesis of 3-carboxylate derivatives of 1,4,5,6,7,8-hexahydroquinoline compared to 3-carbonitrile derivatives. 1,4,5,6,7,8-Hexahydroquinoline-3-carbonitrile was previously synthesized using NH 4 OAc, sulfonated rice husk, nanosized MgO, nano-Fe 3 O 4 @TDI@TiO 2 , citric acid/MCM-48, and K 2 CO 3 catalyst. − Despite the undeniable advantages of these processes, some disadvantages are also present, like the involvement of metal catalysts, nonrecyclable catalysts, high catalyst loading, long reaction time, high temperature, and small substrate scope.…”

Microwave-assisted catalyst-free multicomponent one-pot green synthesis of highly functionalized aminocyanopyridines and (4-hydroxy)quinolines in aqueous medium and its in silico studies

“…4 Acetic acid is also used as a green solvent at high temperatures for pyridine derivative synthesis. 43 There are not many systems available that are more viable in terms of environmental protection and atom economy. Among the nitrogen heterocyclic compounds, aminocyanohydropyridine derivatives are important motifs for organic synthesis and are widely found in many natural products, having different biological activities such as antimicrobial agents, 44 anticancer agents, 45 psychotropic, 46 anti-allergenic, 46 anti-inflammatory, 46 and estrogenic activities, and MK-2 kinase inhibitors 7 (Fig.…”

“…4 Acetic acid is also used as a green solvent at high temperatures for pyridine derivative synthesis. 43 There are not many systems available that are more viable in terms of environmental protection and atom economy.…”

Inverse Electron Demand Diels Alder Reaction of Aza-o-Quinone Methides and Enaminones: Accessing 3-Aroyl Quinolines and Indeno[1,2-b]quinolinones

“…There is a plethora of classical reactions such as Gould–Jacob, Friedländer, Pfitzinger, Skraup, Doebner–von Miller, and Conrad–Limpach for accessing quinoline and its derivatives . Apart from these methods, a number of transition metal catalyzed approaches and green protocols were also developed . In this letter, we describe a new approach to synthesize 3-aroyl/acyl quinolines.…”