Palladium-catalyzed tandem reaction to construct benzo[c]phenanthridine: application to the total synthesis of benzo[c]phenanthridine alkaloids.

A concise and efficient synthesis of benzo[c]phenanthridines was accomplished by the palladium-catalyzed ring-opening coupling of azabicyclic alkene with o-iodobenzoates, followed by tandem cyclization. The strategy was successfully applied in the total synthesis of benzo[c]phenanthridine alkaloids such as sanguinarine, chelerythrine, nitidine and avicine.