An Effective Heterogeneous Copper Catalyst System for C–N Coupling and Its Application in the Preparation of 2-Methyl-4-methoxydiphenylamine (MMDPA)

A ligand-recyclable, environmentally benign heterogeneous catalyst system composed of CuI and polystyrene-supported N(-(4-(aminomethyl)naphthalen-1-yl)-N(-phenyl-1H-pyrrole-2-carbohydrazide (PSAP) has been established for Ullmann type C–N coupling based on the homogeneous catalyst system N′,N′-diphenyl-1H-pyrrole-2-carbohydrazide/CuI. This heterogeneous catalyst system maintained the catalytic effectiveness of the homogeneous catalyst. A variety of functionalized aryl bromides can be efficiently aminated with aryl amines and aliphatic amines with high selectivity for amines over alcohols. Moreover, a practical application of this catalyst system to promote the reaction of commercially available 4-methoxy-2-methylaniline and bromobenzene in 10 mmol scale, provided 2-methyl-4-methoxydiphenylamine (MMDPA) with 93% yield with the merit of the approach being simple operation for work-up and purification.