TMU-16-NH2: A Metal–Organic Framework as an Efficient, Green, and Heterogeneous Catalyst for the Michael Addition Annulations for the Synthesis of a New Series of 2,4-Diphenylpyrido[4,3-d]Pyrimidines

Considering the unprecedented attributes governed by metal-organic framework nanostructures, the present report discloses the fabrication of [Zn₂(H₂N-BDC)₂(4-bpdh)]·3DMF as a Zn-based MOF catalyst (TMU-16-NH₂ (TMU = Tarbiat Modares University)) through the coordination of 2,5-bis(4-pyridyl)-3,4-diaza-2,4-hexadiene (4-bpdh) ligand to the Zn(NO₃)₂·6H₂O salt under hydrothermal approach. In order to certify the successful synthesis of the catalyst, FT-IR, XRD, TGA, Elemental microanalysis, ICP OES and BET measurements were employed. The developed TMU-16-NH₂ catalytic agent acts as a promising candidate to deliver a new class of pharmaceutically relevant 2,4-diphenylpyrido[4,3-d]pyrimidine scaffolds via the Michael addition annulations of benzimidamid hydrochloride to (3E,5E)-3,5-bis-(benzylidene)-4-piperidone reacting species. The devised methodology is accompanied with noteworthy benefits including mild reaction conditions, wide substrate scope, excellent product yields and short reaction span. Besides, facile retrievability and remarkable reusability of the catalyst for 5 successive runs without any appreciable loss in catalytic efficacy are the additional factors that rationalize this protocol as worthwhile. Our findings highlight the potential of using MOFs as efficient and versatile catalysts in organic synthesis and contribute to the growing body of literature on the synthesis of pyrido[4,3-d]pyrimidines with diverse biological activities.