Syntheses of 2-azafluorenones from 3-substituted 4-arylpyridines

3-Substituted 4-arylpyridines (5a-i) were synthesized in good yields by reaction of mixed copper, zinc aryl organometallics (2a-e) with 1-ethoxycarbonyl-pyridinium chlorides (1a-d) followed by o-chloranil oxidation under reflux in toluene. The 4-arylpyridines (5a-i) are obtained predominantly. Having compounds (5a-i) in hand, a convenient method was developed for the synthesis of 2-azafluorenones (7a-f) by using cyclization of 4-arylpyridines (5a-i) with polyphosphoric acid.