An aqua-stable pyridine-functionalized recyclable Zr( iv ) MOF for highly efficient catalytic synthesis of 1,4-dihydropyridines containing drug molecules and sustainable synthesis of quinolines

The design and synthesis of efficient heterogeneous catalysts for organic transformations under sustainable conditions has always remained a significant challenge. In the past decade, MOFs have been extensively employed as heterogeneous catalysts because of their robust nature and tunable porosity, establishing them as a promising class of catalysts. In this endeavor, we present the report of a pyridine-functionalized Zr(IV)-MOF serving as a robust heterogeneous catalyst for the sustainable synthesis of two distinct classes of pharmacologically important heterocyclic drugs under mild conditions. We developed an aqua-stable, pyridine-functionalized Zr(IV)-MOF (1') that serves as a stable heterogeneous catalyst for the multicomponent Hantzsch reaction for the synthesis of 1,4-dihydropyridine (1,4-DHP)-containing drugs and the Friedländer annulation for solvent-free quinoline synthesis, which are two well-established reactions in pharmaceutical synthesis. The catalyst demonstrates excellent catalytic efficacy, broad substrate scope, and high reusability across both reaction pathways. For the Hantzsch condensation, our reported Zr(IV)-MOF enables the synthesis of calcium channel blocker drugs (nemadipine B, nitrendipine, nifedipine and riodipine) under sustainable and mild conditions with high catalytic efficiency. In parallel, the same catalytic system, Zr(IV)-MOF, effectively mediates the Friedländer quinoline synthesis in a solvent-free medium, offering a sustainable alternative to conventional homogeneous acid catalysts for producing biologically active scaffolds. Notably, the reported catalyst restores its structural integrity over repeated catalytic cycles, demonstrating the robustness of this developed MOF. Thus, this study establishes a versatile, robust, and pyridine-functionalized Zr(IV)-MOF as a dual-purpose heterogeneous catalyst, offering a unified, sustainable pathway for achieving two pharmaceutically valuable heterocyclic drug-relevant scaffolds.