Functionalization of Azacalixaromatics by Cu(II)-Catalyzed Oxidative Cross-Coupling Reaction between the Arene C–H Bond and Boronic Acids

Catalyzed by Cu­(ClO4)2·6H2O under mild aerobic conditions using air as the oxidant, azacalix[1]­arene[3]­pyridines underwent a highly efficient oxidative cross-coupling reaction with a large number of aryl-, alkenyl-, and alkylboronic acids to afford diverse functionalized macrocycles. Stoichiometric reactions of an arylboronic acid with isolated and structurally well-defined high valent organocopper compounds indicated the involvement of arylcopper­(II) rather than arylcopper­(III) species as an organometallic intermediate in catalysis.