A highly efficient and regioselective palladium-catalyzed annulation protocol for
a series of linear and terminally substituted 1,2- and 1,3-di(heteroaryl)alkanes to
the corresponding polyheterocyclic arenes is reported. Herein, intramolecular oxidative
coupling involving double C(sp2)–H bond functionalization provides a feasible access to biheteroaryl systems annulated
to a six-membered ring. The methodology is not restricted to six-membered annulations
and was extended to the synthesis of compounds with a seven-membered ring and biheteroaryl
core.
Key words
C–H functionalization - pyrroles - oxidative coupling - palladium - imidazoles