Green and Sustainable Approaches for the Synthesis of Imidazo[1,2-a]Pyridines: Advances, Challenges, and Future...

Imidazo[1,2-a]pyridines are privileged nitrogen-bridged heterocycles with significant applications in medicinal chemistry, materials science, and pharmaceuticals. The synthetic approaches through conventional modes rely on hazardous reagents, toxic solvents, and energy-intensive conditions, posing environmental and economic concerns. To overcome these bottlenecks, recent research has initiated focused efforts on sustainable and eco-friendly strategies aligning with green chemistry principles. This review evaluates recent advancements (2020-2024) in synthesis, including microwave-assisted, ultrasound-assisted, catalyst-free, solvent-free, green solvent-mediated, and homogenous catalyst-assisted approaches. The mechanistic pathways, efficiency, and sustainability of these methodologies are thoroughly analyzed, along with their advantages and inherent limitations. Furthermore, key challenges such as scalability, catalyst recovery, and industrial applicability are discussed alongside innovations such as biocatalysis, photocatalysis, and electrosynthesis. The integration of these advanced strategies is expected to drive the transition toward greener, cost-effective, and scalable methodologies for a sustainable future in heterocyclic chemistry.