SYNTHESES OF 2-AZAFLUORENONES FROM 3-SUBSTITUTED 4-ARYLPYRIDINES

Article abstract of DOI:10.3987/COM-92-6199

3-substituted 4-arylpyridines (5a-i) were synthesized in good yields by reaction of mixed copper, zinc aryl organometallics (2a-e) with 1-ethoxycarbonylpyridinium chlorides (1a-d) followed by o-chloranil oxidation under reflux in toluene.The 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 phosphoric acid.