Synthesis and Biological Activity of Quaternary Quinolinium Salts: A Review

Abstract

Heterocyclic chemistry is the only branch of chemistry that has applications in varied areas such as dyes, photosensitizers, coordination compounds, polymeric materials, biological, and many other fields. Quinoline and its derivatives have always engrossed both synthetic chemists and biologists because of their diverse chemical and pharmacological properties as these ring systems can be easily found in various natural products, especially in alkaloids. Among alkaloids, quinoline derivatives i.e. quinolinium salts have attracted much attention nowadays owing to their diverse biological profile such as antimicrobial, antitumor, antifungal, hypotensive, anti-HIV, analgesics and anti-inflammatory, etc. Quinoline and its analogs have recently been examined for their modes of function in the inhibition of tyrosine kinases, proteasome, tubulin polymerization, topoisomerase, and DNA repair. These observations have been guiding scientists for the expansion of new quinoline derivatives with improved and varied biological activities. Quinolinium salts have immense possibilities and scope to investigate these compounds as potential drug candidates. Therefore, we shall present a concise compilation of this work to aid in present knowledge and to help researchers explore an interesting quinoline class having medicinal potential.

Investigations into the structure–activity relationship in gemini QACs based on biphenyl and oxydiphenyl linker

“…1a ). 4,5 Bis-QACs activity against microorganisms is generally stronger comparing to corresponding monomeric compounds and depends on structure of the gemini molecule. 4 c ,4 g ,5 d Within a range of bis-QACs, cationic gemini bispyridinium salts play important role being broadly used as biocides.…”

Synthesis of Pyrrolo[2,1-a]isoquinolinium Salts from 1-Pyrrolines and Alkynes via Rhodium-Catalyzed C–H Functionalization/N-Annulation Tandem Reaction

“…Quaternary nitrogen heterocyclic salts (QNHS) represent a common motif of biologically active compounds, pharmaceuticals, and natural alkaloids . The simplest synthetic approach toward QNHS is based on the reaction between corresponding N -heterocycles and alkyl halides.…”

Efficient Synthesis of 7H‐Chromeno[3,2‐c]quinolin‐5‐ium Salts and Quinolin‐4‐ones through Acid‐Promoted Cascade Reaction of 3‐Formylchromones and Anilines

“…This core structure is present in natural products such as alkaloid cryptolepine [1] and nitidine [2] (Figure 1). Quinolinium salts have attracted much interest as essential scaffolds found in many biologically active molecules, [3–5] pharmaceuticals, [6–7] and material applications [8–11] . Owing to its strong oxidizing ability at a singlet excited state, quinolinium salts are interesting from theoretical and practical perspectives, and also they can be used as starting materials in organic reactions to construct heterocyclic compounds with special structures [12–17] .…”