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.
Key words
heterogeneous catalysis - copper catalysis - C–N coupling - recyclability - 2-methyl-4-methoxydiphenylamine
(MMDPA)
