Eu-Gd@BiPO4 nano-composite: A potential heterogeneous catalyst in Biginelli reaction

Abstract

The Biginelli reaction found a prominent place among multicomponent reactions owing to the widespread pharmacological importance of the products dihydropyrimidinones (DHPMs). In the present work, DHPM analogs of Vanillin have been synthesized in a one-step Biginelli condensation of Vanillin, 1,3-diketo compound and urea in the presence of 5 mol% of the Eu-Gd@BiPO4 nano-composite catalyst. The heterogeneous catalyst afforded the desired DHPM products of Vanillin in high to excellent yields (85–93%) in a short interval of 30 mins at 80 °C under solvent less conditions. Being heterogeneous, the nano-composite catalyst was easily recovered after the reaction and re-employed in the Biginelli synthesis 5 times without any treatment or significant activity loss. The synthesized DHPM analogs of Vanillin were screened for their antioxidant and antibacterial potential. Out of nine compounds, three compounds 4e, 4h, and 4i were found to show the maximum %RSA of 66.7, 67, and 71% respectively in the DPPH assay and reducing power assay analysis respectively, in comparison to %RSA of 80.9 by the standard Ascorbic acid. The compounds 4a, 4d & 4e were able to inhibit the growth of both gram-positive and gram-negative bacteria to a considerable extent as predicted by the disc diffusion method.