Substituent Effects of 2-Pyridones on Selective O-Arylation with Diaryliodonium Salts: Synthesis of 2-Aryloxypyridines under Transition­-Metal-Free Conditions

An efficient transition-metal-free strategy to synthesize 2-aryloxypyridine derivatives has been developed by a selective O-arylation of 2-pyridones with diaryliodonium salts. The reaction was compatible with a series of functional groups for 2-pyridones and diaryliodonium salts such as halides, nitro, cyano, and ester groups. The substituents at the C6-position of 2-pyridones favored O-arylation products because of steric hindrance. The reaction was easily performed on a gram-scale and 6-chloro-2-pyridone was a good precursor to access various unsubstituted 2-aryloxypyridines by dehalogenation. A P2Y1 lead compound analogue could be prepared in good yield over two steps.