OICC Press Iranian Journal of Catalysis 2345-4865 14 2 2024 05 25 Natural base catalysis in the sustainable synthesis of functionalized 2-amino-4H-chromenes 10.57647/j.ijc.2024.1402.16 EN U. P. Patil Department of Chemistry, ACS College, Palus-416310, Dist: Sangli, MS, India (affiliated to Shivaji University, Kolhapur-416004, MS, India). 0000-0001-6519-2494 S. U. Patil Department of Life Sciences, KRP Kanya Mahavidyalaya, Islampur-415409, Dist: Sangli, MS, India (affiliated to Shivaji University, Kolhapur-416004, MS, India). 0000-0002-9370-4220 Journal Article 2024 05 25   Functionalized 2-amino-4H-chromenes have been successfully synthesized via cyclization of C-H activated acids, aromatic aldehydes, and active methylene compounds using a natural base catalyst derived from waste snail shells (Bellamya bengalensis) in the water at ambient temperature. Freshwater snail shells are significant biological materials with diverse uses. As an economical and environmentally benign alternative to traditional stoichiometric reagents and expensive metal catalysts, the waste shells of snails worked well as a heterogeneous base catalyst in hetero-cyclization. The as-prepared catalyst was analyzed using FTIR, XRD, EDS, SEM, TEM, and TGA tools. The chemical analysis revealed the predominance of CaO, which in the water possibly provides an alkaline medium to the reaction through which the reaction accelerates efficiently and offers a quantitative yield of the desired product. Catalytic reusability showed slight leaching of the catalyst that could be recovered and reused.   Highlights   ·         Waste shells of snail-derived catalyst employed in synthesizing densely functionalized 2-amino-4H-chromenes. ·         Utilization of natural feedstock in catalysis leads to cost-efficient and sustainable methodology. ·         Characterization tools exhibited a higher concentration of Ca species in snail shells. ·         CaO-enriched catalyst possibly responsible for promoting heterocyclization more efficiently in an aqueous medium. ·         Green credentials of the protocol are enhanced using water as a solvent, ambient temperature conditions, and achieving high yields.