Efficient and robust superparamagnetic copper ferrite nanoparticle-catalyzed sequential methylation and C–H activation: aldehyde-free propargylamine synthesis

We have described a method for oxidative cross-coupling reactions between N-alkyl anilines and terminal alkynes forming N-aryl-N-methylpropargylamines. Superparamagnetic CuFe sub(2)O sub(4) nanoparticles were employed as efficient and robust catalyst. The optimum conditions involved the use of tert-butyl hydroperoxide (TBHP) as oxidant and methylating reagent in dimethylacetamide (DMA) solvent at 140 degree C. The two-step reaction, methylation and C-C cross-coupling, proceeds efficiently and has high selectivity, and good conversions were achieved in short reaction times. Preliminary mechanistic investigation was conducted. The CuFe sub(2)O sub(4) nanoparticles could be facilely separated from the reaction mixture by magnetic decantation and could be reused several times with only a slight decrease in catalytic activity.