Defect-rich MOF-303 as a dual acid-base heterogeneous catalyst for the one- pot Biginelli synthesis of dihydropyrimidinones

Bifunctional MOF-303 (Al) exhibits promising catalytic activity for the Biginelli reaction. However, its intrinsic microporosity may hinder reactant and product diffusion and reducing efficiency. Introducing defects is crucial for enhancing its catalytic performance. In this work, defect-rich MOF-303 was prepared by grinding the hydrothermally synthesized MOF-303 into a fine powder. The resulting material was thoroughly characterized and exhibited excellent catalytic performance in the solvent-free synthesis of diverse dihydropyrimidinones under moderate reaction conditions, achieving yields between 94% and over 99%. Moreover, the catalyst was successfully recycled over five cycles with minimal activity loss. The structures of the obtained products were confirmed by IR, ¹H NMR, and melting point analysis. The simple preparation method using commercially inexpensive reagents, high catalytic performance under mild conditions, and recyclability of defect-rich MOF-303 highlight its potential as an efficient and sustainable catalyst for the Biginelli reaction.