Facile One-Pot Direct Arylation and Alkylation of Nitropyridine N-Oxides with Grignard Reagents

Facile arylation and alkylation of nitropyridine N-oxides were developed through the reactions of Grignard reagents with nitropyridine N-oxides. For the same 4-nitropyridine N-oxide, arylation occurred at the 2- (or 6-) position, whereas alkylation occurred at the 3-position in an adjustably site-selective manner. The cooperative action of the two groups was discovered in the reactions of 3-nitropyridine N-oxides. This protocol can find wide applications in building various pyridine compounds as illustrated in total syntheses of Emoxipin and Caerulomycin A and E.