Silica Supported Boric Acid (H₃BO₃‐SiO₂): An Extravagant Catalyst for One‐Pot Transesterification‐Biginelli Reaction Under Solvent‐Free Condition

Abstract Present study aimed to develop an eco‐friendly protocol for the synthesis of diverse structure of 3,4‐dihydropyrimidin‐2(1H)‐one/thione via one‐pot transesterification–multicomponent reaction using silica‐supported boric acid (H 3 BO 3 ‐SiO 2 ) as catalyst. This one‐pot trans‐esterification of commercially available β ‐ketoesters such as methyl or ethyl acetoacetate followed by multicomponent reactions with aldehydes and urea or thiourea under solvent‐free conditions at 100 °C afforded diverse structures of DHPM's. The catalyst used in the reaction can be recycled without significant loss of its activity which was verified by comparing SEM‐EDX micrographs of freshly prepared catalyst with the recycled one. The notable features of the present protocol are its ease‐of‐use, wide substrate scope, mild reaction conditions, most simplified work‐up process, less hazardous catalysts and so on. Thus, in our opinion, the present methodology is a superior and more practical greener route for the production of dihydropyrimidinones/thiones of biological importance.