Direct ortho-arylation of N-phenacylpyridinium bromide by palladium-catalyzed C-H-bond activation.

A novel palladium catalyzed direct ortho-arylation of N-phenacylpyridinium bromide was developed. The amazing N-phenacyl group regioselectively activates the C-H bond of pyridine and automatically departs from the arylated products. A kinetic isotope effect study proved that the reaction went through a C-H-bond activation pathway and 2,6-diphenylpyridine was produced stepwise from 2-phenylpyridine.