Heterogeneous Copper Nanoparticles Promoted Mannich Reaction

Significance

Copper nanoparticles were used for the Mannich reaction of ketones with aldehydes and amines. Thus, the reaction of cyclo­hexanone or acetophenones (1 mol equiv) with benzaldehydes (1 mol equiv) and anilines (1 mol equiv) was performed in the presence of copper nanoparticles (Æ 182 nm) to give the corresponding β-amino ketones in 73-97% yield (18 examples). The authors prepared nanoparticles of Æ = 10, 20, 30, 50 and 70 nm and found that the nanoparticles of Æ = 20 nm were the most active catalysts [R^¹, R^², R^³ = H; 87% (Æ = 10 nm); 95% (Æ = 20 nm); 84% (Æ = 30 nm); 71% (Æ = 50 nm); 65% (Æ = 70 nm)].