A silica gel-supported schiff base palladium nanocatalyst for sonogashira cross-coupling and synthesis of an anti-cancer chemotherapeutic agent

This work outlines the synthesis of a low-cost reusable silica gel-supported Schiff-base palladium nanocatalyst and its application in the synthesis of anti-cancer agent Eniuracil via the Sonogashira reaction. Silica gel was functionalized with amino containing silyl followed by the generation of a Schiff base through reaction with 1,10-phenanthroline-2,9-dicarboxaldehyde. Palladium was then coupled in the presence of hydrazine hydrate, resulting in the formation of the silica gel-supported Schiff-base palladium nanocatalyst (Si@SBPdNPs 3). Successful palladium incorporation was confirmed through Fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analyses. Scanning Electron Microscope (SEM) images revealed spherical silica gel particles and Transmission Electron Microscopy (TEM) analysis indicated an average palladium nanoparticle size of 5.92 ± 0.1 nm. The Inductively Coupled Plasma (ICP) and Energy Dispersive X-ray (EDX) data confirmed the anchoring of 0.27 mol% of palladium to the Schiff-base in the catalyst. The industrial efficacy of the catalysts is demonstrated through its application in carbon-to-carbon bond formation between aryl halides and aromatic alkyne via the Sonogashira reaction. Furthermore, the catalyst proved effective in the synthesis of the anti-cancer agent Eniuracil, a vital component in fluoropyrimidine-based chemotherapy. The catalyst exhibited reusability without significant loss of productivity, demonstrating its robustness in C [tbnd]C bond formation in organic synthesis.