Synthesis and characterization of silica@copper core-shell nanoparticles: Application for conjugate addition reactions

Silica@copper (SiO2@Cu) core-shell nanoparticles were synthesized and well characterized by XRD, TEM, AFM, XPS, UV/Vis, TGA-MS, and ICP-AES techniques. The synthesized SiO2@Cu core-shell nanoparticles were employed as catalysts for the conjugate addition of amines to alpha,beta-unsaturated compounds in water to obtain beta-amino carbonyl compounds in excellent yields in shorter reaction times. Furthermore, the catalyst works well for hetero-Michael addition reactions of heteroatom nucleophiles such as thiols to alpha,beta-unsaturated compounds. As the reaction is performed in water, it allows for easy recycling of the catalyst with consistent activity.