Synthesis and application of an effective magnetic catalyst immobilized copper oxide for the one-pot ultrasound-assisted synthesis of 1,4-dihydropyridines

In this study, Fe₃O₄ was modified with a biocompatible carbohydrate D-(+)-ribonic γ-lactone (RL) followed by immobilization with CuO nanoparticles (CuO NPs) to produce Fe₃O₄-APTES-RL-CuO as a Lewis acid catalyst. The sustainable RL can be utilized as a novel support for CuO NPs with increased catalytic activity. RL with plenty of hydroxyl groups not only catch the CuO NPs and prevents them from agglomeration but also, prevails upon immobilization of CuO NPs making the nanohybrid RL-supported CuO NPs significantly stable. This green and effective heterogeneous catalyst can be used for one-pot ultrasound-assisted synthesis of 1,4-dihydropyridines (1,4-DHPs) with high yield (95٪) and short time (15 min). The catalyst can be separated easily and cleanly by using an external magnet. This nanomagnetic catalyst is reused five times without any remarkable reduction in its activity. To illustrate the structure of the catalyst and characterize its physicochemical properties, different techniques like FT-IR, XRD, FE-SEM, EDS, TGA, and VSM were applied.