Immobilized L–Proline on Carbon Nanofibers as Organocatalysis for Enantioselective Biginelli Reaction

A mixture of carbon nanofibers with a twisted morphology is synthesized by catalytic pyrolysis of acetylene at ۷۰۰ œC using ZnFe۲O۴ nanoparticles as the catalyst precursor by chemical vapor deposition method by using acetylene as carbon source. Obtained carbon nanofibers were chemically functionalized by treatment with aryl diazonium salts to provide binding anchors for L-proline molecules. L-proline as the catalytic active site was immobilized on carbon-produced nanofibers by using a covalent binding strategy. The structural and chemical nature of the catalyst was characterized by a variety of techniques including XRD, FTIR, Raman, and SEM. An efficient one-pot enantioselective synthesis of Biginelli reaction by three-component reaction of ethyl acetoacetate, benzaldehyde, and urea in water in the presence of Immobilized L-proline on carbon nanofibers is reported. A series of dihydropyrimidinones were obtained in high yields with good to high enantioselectivities. The as-synthesized polymers were characterized with NMR, FTIR, melting points, mass spectroscopy, and polarimetry. The as-prepared catalyst is efficient, selective, durable, recyclable, and reusable.

Keywords:

CVD , CNFs , ZnFe۲O۴ , Enantiomeric excess , dihydropyrimidinones