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

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 ana -logs 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 degrees 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 sig-nificant activity loss. The synthesized DHPM analogs of Vanillin were screened for their antioxidant and anti-bacterial 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.

Automated summary

In this study, DHPM analogs of Vanillin were synthesized in a one-step Biginelli condensation using a Eu-Gd@BiPO4 nano-composite catalyst. The catalyst showed high efficiency and the reaction provided good yields in a short time under solventless conditions. The synthesized compounds exhibited promising antioxidant and antibacterial activities.