Recent Innovations in Synthetic Methodologies and Patent Landscape of Quinoline Analogues: A Comprehensive Review

Abstract: Quinoline is a general group of heterocyclic compounds that have garnered much interest in medicinal chemistry and drug development due to their wide range of pharmacological effects. Pyridine ring fused with benzene defines the class of chemical compounds known as quinolines. Quinoline is a weak tertiary base, also known as 1-aza-naphthalene. Numerous patents have been filed for the synthesis of quinoline-based compounds, detailing their derivatives and their uses. Here, we have discussed the methods of quinoline synthesis, structural alterations, and patents showing its importance in various industries. Quinolines have been investigated as antimalarial substances, with substances, like quinine and chloroquine, serving as notable examples, and they have also been investigated to possess anti-inflammatory, anti-tumor, and CNS activity. The synthesis of quinoline is also subjected to several recognized procedures. The variations in the ring system and various synthetic approaches are the key highlights of the article, and it includes the various catalysts that could be recycled and reused by the assisted technique, which increases the yield and requires less time for the synthesis (ultrasound-promoted synthesis, one-pot reaction, and microwave and photocatalytic reactions). The development of synthetic procedures can help in the sustainable synthesis of quinoline derivatives.