A comprehensive review on the rational design of MOF-based heterogeneous catalysts for the classic Biginelli reaction

The classic Biginelli reaction is a sustainable and powerful tool for synthesizing dihydropyrimidinone scaffolds (DHPMs) through an acid-catalyzed one-pot-three component process. Since such a multi-component reaction is accompanied by an entropy decrease in the transition state, utilizing a heterogeneous porous catalyst with abundant acidic sites will be beneficial. Activating reagents within catalyst cavities, which act as nanoreactors, helps stabilize the tightly bound transition state, reducing the activation energy and accelerating the reaction rate. As a unique class of porous crystalline materials with intrinsic acidic properties, metal–organic frameworks (MOFs) offer promising potential for catalyzing this reaction. Their catalytic activity originates from defects in the crystalline lattice and/or from functional groups on their organic linkers and/or inorganic nodes. Additionally, encapsulating catalytic guest species inside their pores can further enhance their catalytic activity. Furthermore, functionalizing the outer surface of MOF particles or hybridizing them with other materials can further tailor their properties, offering improved performance based on the nature of the materials incorporated. This review explains the current state-of-the art in using MOF-based solid platforms as porous heterogeneous catalysts for the classic Biginelli reactions. After providing a background introduction to the Biginelli reaction, its mechanistic aspects and the methods for characterizing MOF-based catalysts are reviewed. Finally, conclusion, challenges, and future trends were discussed. Despite the numerous reviews exist on the Biginelli reaction, no comprehensive study has specifically focused on the use of MOFs as catalysts for this reaction. This review aims to address this gap by presenting a detailed overview of MOFs as powerful and versatile heterogeneous catalysts for the Biginelli reaction. We hope this critical appraisal will serve as a foundation for researchers to design and develop more efficient MOF-based catalysts for this important transformation.