Reactivity of Substituted Bromothiophenecarboxylates in Palladium-Catalyzed N-Arylation of Hetarylamines

The N-arylation of hetarylamines by reaction of aminopyridines or aminoquinolines with substituted bromothiophene-2- or -3-carboxylates is described. From 2-aminopyridines and 1-aminoisoquinoline, polycyclic compounds were obtained in one-pot, two-step reactions: C-N coupling is followed by intramolecular cyclization involving the nitrogen atom of the heterocyclic ring and the carboxylate. Steric hindrance seems to be a limitation for the latter reaction, because when 2-amino-6-picoline was used, the corresponding dihetarylamines were obtained.