Thiophene-containing dinucleating ligands for the copper-catalyzed oxidative coupling of 2,6-dimethylphenol

The copper-catalysed polymerisation of 2,6-dimethylphenol leads to poly(2,6-dimethyl-1,4-phenylene) ether, which is a widely used high-performance thermoplastic. The oxidative coupling reactions have been performed in acetonitrile with structurally related dinucleating phenol-based “end-off” compartmental N,O,S- ligands. The bio-inspired copper catalysts appeared to be of great interest for a better understanding of the parameters governing the catalytic activities. Steric effects (difference between three side-arm and four side-arm ligands), as well as electronic effects (thiophene versus pyridine substituents) have been evidenced on the initial dioxygen-uptake rates.