CuO-ZnO Nanocomposite as a Green and Reusable Catalyst for One-Pot Green Synthesis of Dibenzo[a,j]xanthene under Solvent-Free Conditions

A CuO–ZnO nanocomposite was developed as a green, efficient, and reusable catalyst for the solvent-free, one-pot multicomponent synthesis of 14-aryl-H-dibenzo[a,j]xanthenes via the cyclocondensation of aromatic aldehydes with β-naphthols. The catalyst was prepared through a simple ball-milling method using CuO and ZnO powders in 1:1 and 2:1 ratios and was thoroughly characterized by UV–Vis spectroscopy, powder X-ray diffraction (pXRD), scanning electron microscopy (SEM), and EDAX with elemental mapping. The protocol offers several advantages, including operational simplicity, elimination of hazardous solvents, and high product yields. A series of 14 derivatives (3a–3n) was synthesized with good to excellent yields. Notably, the catalyst demonstrated excellent recyclability, retaining its activity over five consecutive cycles without significant loss in efficiency. The combination of solvent-free conditions, high product purity, and sustainable catalytic performance highlights the practical potential of the CuO–ZnO nanocomposite in green organic synthesis.