MCM-41@Schiff base-Co(OAc)(2) as an efficient catalyst for the synthesis of pyran derivatives

Heterogeneous ordered mesoporous silica materials catalyst, MCM-41@Schiff base-Co(AcO)(2), reveals high catalytic performance within the synthesis of pyran derivatives using the multicomponent reaction of aldehydes, malononitrile and 2-naphthol (or cyclohexane-1,3-dione) in water. The reactions afforded the desired products in high yields (up to 97% and 95%). The substantial feature is that the mesoporous-complex catalyst could be easily separated from the reaction mixture by centrifugation and reused at least 6 times with more than 80% yield in activity. The gram-scale experiments were achieved with good yields and implied that the catalytic method was effective and convenient for heterocyclic synthesis. What is more, the synthesized catalyst was characterized using various spectroscopic techniques to obtain the structural and functional features. The analysis results confirmed that the Co-Schiff base complex immobilized on the surface of mesoporous materials MCM-41. Finally, a plausible reaction mechanism was proposed.