Regioselective Pyridination of m-Benziporphyrin

Stępień, M.; Latos-Grażyński, L.
Org. Lett. 2003, 5, 3379-3381 | view at publisher's site

Reaction of tetraaryl-m-benziporphyrin with pyridine and silver tetrafluoroborate yields 22-pyridiniumyl-m-benziporphyrin as the only substitution product. This compound is further rearranged to a fused m-benziphlorin containing a 4a-azafluorene fragment. A mechanism involving a high-valent silver complex is proposed for the pyridination reaction.