Copper catalyzed N-arylation of amidines with aryl boronic acids and one-pot synthesis of benzimidazoles by a chan-lam-evans N-arylation and C-h activation/c-N bond forming process.
Résumé
Mono-N-arylation of benzamidines 1 with aryl boronic acids 2 was effectively achieved in the presence of a catalytic amount of Cu(OAc)(2) and NaOPiv under mild aerobic conditions. Combining this step with an intramolecular direct C-H bond functionalization, catalyzed by the same catalytic system but under oxygen at 120 °C, afforded benzimidazoles 3 in good to excellent yields.