Metal Oxide/MWCNT–Supported Catalysts for One-Pot Multicomponent Synthesis of Fused Azepine Derivatives: Recent Advances and Biological Relevance

Abstract

This review highlights recent (2021–2026) advances in the application of metals oxide (Fe₃O₄, CuO, ZnO, Ag, TiO₂, and CdO)@multiwalled carbon nanotubes (MO@MWCNTs)–supported catalysts for the one-pot multicomponent synthesis of fused azepine derivatives with five-, six-, and seven-membered rings, an important class of seven-membered nitrogen-containing heterocycles with diverse pharmacological properties. MO@MWCNTs-supported catalysts have emerged as highly efficient and versatile platforms for promoting one-pot multicomponent reactions (MCRs) owing to exceptional surface area, thermal stability, and tunable functionalization. The synergistic role of MO@MWCNTs in facilitating catalyst dispersion, improving recyclability, and enabling mild reaction conditions is critically discussed. These catalytic systems combine the exceptional surface area, thermal stability, and tunable functionalization of MO@MWCNTs with the reactivity of active catalytic species, enabling enhanced reaction efficiency and selectivity. Emphasis is placed on green synthesis approaches that minimize waste, reduce reaction time, and eliminate harsh conditions or toxic solvents. The synergistic role of MO@MWCNTs in facilitating catalyst dispersion, improving recyclability, and enabling mild reaction conditions is critically discussed.