<i>N</i> ‐Unsubstituted Dihydropyridines and Pyridones via Multicomponent Synthesis Under a Bio‐Derived Heterogeneous Catalyst

Abstract In our exploration of metal‐free and cost‐effective heterogeneous catalysts for MCRs, we identified a novel system: piperazine immobilized within an agar matrix, functioning as a recyclable and reusable catalyst. This system efficiently facilitates the synthesis of dihydropyridines (DHPs) via one‐pot condensation of dimedone, aldehydes, ammonium acetate, and various active methylene compounds—specifically malononitrile, acetophenone, or Meldrum's acid. A broad range of products was obtained, underscoring the versatility of the methodology. Notably, our prior investigations demonstrated this catalyst's efficacy in synthesizing N‐aryl‐substituted DHPs, affirming its general applicability. Additionally, fluorescence and UV absorption studies, along with in‐depth characterization using 2D NMR spectroscopy, were conducted to confirm the structure and peak assignments of the synthesized products.