New Stable Ligand-Free Cu(I) Catalyst Supported on Weakly Acidic Polyacrylate Resin: Case Study in
Synthesis

Nitin S. Kore, Pavel Pazdera

Centre for Syntheses at Sustainable Conditions and their Management, Faculty of Science, Masaryk
University, Kamenice 5, CZ-62500 Brno, Czech Republic

Catalysis by Cu(I) catalysts like CuI is very well known for various C-C, C-N, C-O  and similar
oxidative coupling reactions, catalytic oxidation processes as well as for click chemistry
reactions.  Problem of using homogeneous catalyst and ligand remains a challenge as it is difficult
to separate and recycle and as a result produce unnecessary toxic waste. A simple and efficient
methodology for Cu(I) catalyzed C-N cross coupling post-Ullmann reactions and some click chemistry
reactions were studied using Cu(I) ion immobilized on inexpensive industrial weakly acidic
cation-exchanger resin as a catalyst. Coupling reaction of different aryl amine with
4-chloropyridine were carried out using ligand free Cu(I) ion immobilized on inexpensive industrial
weakly acidic cation-exchanger resin as a catalyst. C-N cross coupling product was obtained in good
yield as one hydrogen was easily replaced with aryl amine containing an electron donating group and
slightly deactivating group (Cl, Br, I, F).  Unexpectedly, novel triaryl amine molecules obtained
from the coupling reaction of 4-chloropyridine with aryl amine consisting a strong electron
withdrawing group like CN or NO[2]. The same catalytic system was found active for click chemistry.
In cycloaddition reaction of arylazide with aliphatic, aromatic and heterocyclic terminal alkyne
compounds almost quantitative yield corresponding 1,2,3 triazole compound. This presented supported
catalytic system is very stable, insensitive to moisture or atmospheric air and hence reactions can
be carried out under open atmospheric and mild condition. Our catalytic system is less-toxic,
economical, easily separable and recyclable.