Copper Acetylacetonate–Immobilized Halloysite Nanotube: An Efficient Natural and Green Catalyst for the Synthesis of 4H‐Chromenes at Room Temperature

• Published in: Applied organometallic chemistry 2025-01, Vol.39 (1), p.n/a
• Main Authors: Mousavi‐Mashhadi, Seyed Ali, Shiri, Ali
• Format: Article
• Language: English
• Subjects: 4H‐chromenes; Catalysts; Chemical bonds; Chemical synthesis; Copper; copper acetylacetonate; halloysite nanotubes; Malononitrile; multicomponent reactions; Nanotubes; natural support; Room temperature
• ISSN: 0268-2605; 1099-0739
• DOI: 10.1002/aoc.7944

ABSTRACT A new copper acetylacetonate immobilized on halloysite nanotube (HNT) was synthesized. For this purpose, (3‐aminopropyl)trimethoxysilane (AMPTSi) was covalently bonded to the surface of halloysite nanotubes, and then copper acetylacetonate was immobilized onto the modified support. The chemical and physical structure of Cu(acac)2/AMPTSi/HNTs were characterized via various analyses such as TEM, SEM, EDS, FTIR, XRD, TGA, and N2 adsorption–desorption. The efficiency of this catalyst was studied in a one‐pot three‐component reaction of benzaldehydes, dimedone, and malononitrile/ethyl cyanoacetate for the synthesis of 4H‐chromenes. For all substrates, good to excellent yields of the corresponding 4H‐chromenes were obtained. The study synthesized a novel copper acetylacetonate–immobilized halloysite nanotube (Cu(acac)2/AMPTSi/HNTs) and demonstrated its effectiveness as a green catalyst for the room–temperature synthesis of 4H–chromenes via a one–pot, three–component reaction. Characterization confirmed the successful modification of halloysite nanotubes, whereas the catalyst exhibited high yields, short reaction times, and good reusability across six cycles. The method highlighted environmental benefits, including mild reaction conditions and eco–friendly solvents, positioning the catalyst as a sustainable option for heterocyclic compound synthesis.