Syntheses of 2-Azafluorenones from 3-Substituted 4-Arylpyridines
摘要:
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.
Regio- and Chemoselective Addition of Mixed Copper, Zinc Benzylic Organometallics to Functionalized Pyridinium Salts: A Facile Synthesis of Functionalized 4-Benzylpyridines
2′,3-Disubstituted 4-benzylpyridines 4 were synthesized in good yield by reaction of mixed copper, zinc benzylic organometallics 1 with 3-substituted 1-(ethoxycarbonyl)pyridinium chlorides 2 followed by sulfur oxidation under reflux in decalin.