Recent advancement in the synthesis of quinoline derivatives via multicomponent reactions

The synthesis of quinoline derivatives through multicomponent reactions (MCRs) has emerged as an efficient and versatile strategy in organic synthesis. MCRs offer the advantage of constructing complex molecular architectures in a single step, utilising multiple starting materials in a convergent manner. This review provides an overview of recent advancements in the field of quinoline synthesis via MCRs. Various MCRs, such as the Povarov reaction, the Gewald reaction, and the Ugi reaction have been successfully employed for the synthesis of diverse quinoline scaffolds. These methodologies not only showcase high atom economy but also allow the incorporation of structural diversity into the final products. The versatility of MCRs enables the introduction of functional groups and substitution patterns tailored to specific applications. This review highlights the significance of quinoline derivatives in medicinal chemistry, materials science, and other interdisciplinary areas. The continuous innovation and development of novel MCR-based approaches for quinoline synthesis hold great promise for the rapid and efficient generation of valuable compounds with a wide range of biological and physicochemical properties.

An environmentally benign regioselective synthesis of 2-benzyl-4-arylquinoline derivatives using aryl amines, styrene oxides and aryl acetylenes

A novel and an expedient metal- and solvent-free synthesis of a wide variety of 2-benzyl-4-arylquinoline derivatives is described from readily available aryl amines, styrene oxides and aryl acetylenes in the presence of 10 mol% molecular iodine. This domino reaction occurs under metal- and solvent-free conditions at 120 °C, which avoids the usage of metal catalyst and as a consequence generation of metal waste. The salient features of this methodology are the use of simple starting materials, ease of handling, high regioselectivity, shorter reaction time, atom-economical, step-economical, the formation of one C-N and two C-C bonds and a wide range of functional groups tolerance.

Metal-free synthesis of quinoline-2,4-dicarboxylate derivatives using aryl amines and acetylenedicarboxylates through a pseudo three-component reaction

An efficient, useful and one-pot protocol for the synthesis of quinoline-2,4-dicarboxylate scaffolds is accomplished from aryl amines and dimethyl/diethyl acetylenedicarboxylates using 20 mol% molecular iodine as a catalyst in acetonitrile at 80 °C. In addition, the mechanistic explanation for the formation of the desired products is disclosed. The pivotal role of molecular iodine in the formation of the major products, diester quinoline derivatives, and the minor product, triesters, in two cases is described in the mechanism. The notable advantages of this method are non-involvement of a metal catalyst, avoiding of metal contamination in the final product as well as waste generation, use of a low cost and eco-friendly catalyst, ease of handling, high regioselectivity, shorter reaction time, the formation of one C-N and two C-C bonds and a broad substrate scope with good yields.

Environmentally Friendly Nafion-Catalyzed Synthesis of Substituted 2-Ethyl-3-Methylquinolines from Aniline and Propionaldehyde under Microwave Irradiation

Herein, we report a facile synthetic methodology for the preparation of 2,3-dialkylquinolines from anilines and propionaldehydes. This cyclization involved environmentally friendly Nafion® NR50 as an acidic catalyst with microwave irradiation as the heating source. A series of substituted 2-ethyl-3-methylquinolines were prepared from various anilines and propionaldehyde derivatives through this protocol with good to excellent yields. Some new chemical structures were confirmed by X-ray single-crystal diffraction analysis and the related data were provided. The plausible reaction mechanism studies are also discussed.

The Protection of Crocin Against Ulcerative Colitis and Colorectal Cancer via Suppression of NF-κB-Mediated Inflammation

Background: In China, the incidence of ulcerative colitis (UC) is increasing every year, but the etiology of UC remains unclear. UC is known to increase the risk of colorectal cancer (CRC). The aim of this study was to investigate the protective effects of crocin against UC and CRC in mouse models.

Methods: Crocin was used to treat the dextran sodium sulfate (DSS)-induced UC mice for 3 weeks, and Apc^MinC/Gpt mice with colorectal cancer for 8 weeks. Proteomics screening was used to detect changes in the protein profiles of colon tissues of UC mice. Enzyme-linked immunosorbent assays and western blot were used to verify these changes.

Results: Crocin strongly reduced the disease activity index scores of UC mice, and improved the pathological symptoms of the colonic epithelium. The anti-inflammatory effects of crocin were indicated by its regulation of the activity of various cytokines, such as interleukins, via the modulation of nuclear factor kappa-B (NF-κB) signaling. Crocin significantly suppressed tumor growth in Apc^MinC/Gpt mice and ameliorated pathological alterations in the colon and liver, but had no effects on spleen and kidney. Additionally, crocin significantly decreased the concentrations of interleukins and tumor necrosis factor-α in the sera and colon tissues, suggesting its anti-inflammatory effects related to NF-κB signaling. Finally, 12-h incubation of SW480 cells with crocin caused cell cycle arrest, enhanced the apoptotic rate, promoted the dissipation of mitochondrial membrane potential, and the over-accumulation of reactive oxygen species. From the theoretical analyses, phosphorylated residues on S536 may enhance the protein-protein interactions which may influence the conformational changes in the secondary structure of NF-κB.

Conclusion: The protective effects of crocin on UC and CRC were due to its suppression of NF-κB-mediated inflammation.

Copper(ii) triflate catalyzed three-component reaction for the synthesis of 2,3-diarylquinoline derivatives using aryl amines, aryl aldehydes and styrene oxides

An efficient and expedient synthetic protocol is reported for the synthesis of 2,3-diarylquinoline derivatives from readily available aryl amines, aryl aldehydes and styrene oxides using 10 mol% copper(ii) triflate by employing three-component reaction.