• Reviews recent advances in ionic liquids as green platforms for pyran synthesis . • Surveys methodological diversity including microwave-assisted, mechanochemical, photo/enzyme hybrid, and aqueous one-pot protocols. • Discusses task-specific and supported IL systems (acidic, basic, chiral, magnetic, ferrocene-tagged, biodegradable, and nanoparticle-supported). • Critically evaluates mechanistic insights, recyclability, scalability, and life cycle considerations , outlining opportunities for future eco-compatible pyran chemistry. Pyrans and their fused derivatives are privileged oxygen heterocycles with broad biological activity and industrial relevance, yet their sustainable synthesis remains a continuing challenge. Ionic liquids (ILs) have emerged as versatile, green platforms for the efficient construction of pyran frameworks: as designer solvents, recyclable catalysts, and multifunctional reaction media that stabilize transition states, accelerate rates, and enhance selectivity. This review surveys recent advances in IL-enabled pyran chemistry, emphasizing methodological diversity (microwave-assisted, mechanochemical, photo/enzyme hybrid, and aqueous one-pot protocols), task-specific IL designs (acidic, basic, amino-functionalized, chiral, magnetic, ferrocene-tagged, and biodegradable variants), and supported/heterogeneous systems (nanoparticle, halloysite, carbon nanotube and magnetic supports). Representative transformations include Prins cyclizations, Knoevenagel–hetero-Diels–Alder cascades, domino and tandem sequences, and one-pot syntheses of 4H-pyrans, tetrahydrobenzobpyrans, pyrano-annulated heterocycles and spiropyrans. We highlight mechanistic insights, catalyst recyclability, process intensification, and examples of bioactive product discovery. Challenges such as scalability, IL toxicity and biodegradability, and life cycle considerations are discussed alongside opportunities afforded by IL and metal composites, immobilized organocatalysts, and green extraction techniques. By synthesizing these developments, the review demonstrates how ionic liquids furnish efficient, selective, and increasingly sustainable routes to pyran architectures, and outlines future directions for translating laboratory advances into practical, eco-compatible synthesis.
Maity et al. (Sun,) studied this question.