A Review on Green Synthetic Approaches in the Development of Quinoline Analogues

ABSTRACT Quinoline is a privileged nitrogen‐containing heterocycle that has attracted considerable attention owing to its structural versatility and broad‐spectrum biological potential, particularly in the design and discovery of anti‐infective agents. Despite being well‐established, conventional methods for the synthesis of quinoline analogues, many of these rely on energy‐intensive processes, hazardous solvents, harsh reaction conditions, and non‐recyclable reagents or catalysts, raising serious safety and environmental concerns. Consequently, green chemistry has become an attractive alternative for developing more sustainable, energy‐efficient, atom‐economical, and environmentally friendly synthetic processes. This review provides a comprehensive overview of recent developments in environmentally friendly strategies for the synthesis of quinoline analogues, with particular emphasis on metal‐free catalytic systems, solvent‐free approaches, microwave‐ and ultrasonic‐assisted techniques, organocatalysis, biocatalysis, one‐pot multicomponent reactions, ionic liquids, nanoparticle‐mediated systems, electrochemical transformations, and visible‐light‐promoted photocatalytic strategies. In addition, the substrate scope, reaction efficiency, and catalytic recyclability of these approaches are critically discussed to provide a comprehensive overview of their sustainable and synthetic utility. Thus, this review emphasizes recent progress in environmentally friendly quinoline synthesis and provides an up‐to‐date resource to support the wider adoption of sustainable synthetic strategies and to guide the rational development of greener quinoline‐based scaffolds for future use in heterocyclic and medicinal chemistry.