Science of Synthesis

Spitzner, D., Science of Synthesis, (2005) 15, 211.

Pyridine 1-oxides, e.g. ‌897‌ and ‌901‌, are easily nitrated with concentrated nitric acid in sulfuric acid, acetic acid, or dichloromethane, or with potassium nitrate in concentrated sulfuric acid at 80°C (‌Scheme 302‌);[‌792‌,‌1154‌,‌1155‌] the nitro group enters the 4-position of the heterocyclic system, e.g. formation of ‌900‌ and ‌902‌.[‌915‌,‌1153‌] Pyridine 1-oxides bearing electron-donating groups at C2 (amino, alkoxy) undergo 5-substitution but also give mixtures of the corresponding 4- and 5-nitropyridine 1-oxides.[‌1156‌–‌1158‌] An electron-withdrawing group at C3 of pyridine 1-oxide ‌903‌ leads to nitration at C5 and formation of ‌904‌ in 50% yield (‌Scheme 302‌).[‌1159‌]

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References

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• 8.Meeeee-Meee, (8888) 88/8, 888.
• 8.Meeeee-Meee, (8888) 88/8, 888.
• 8.Meeeee-Meee, (8888) M 8e, 888.