Yield:62516-08-9 90%

Reaction Conditions:

Stage #1: 5-bromo-2-methyl-pyridine-N-oxidewith nitric acid in sulfuric acid at 20 - 90; for 2 h;
Stage #2: with sodium carbonate in sulfuric acid;water; pH=10;

Steps:

7

5-bromo-2-methyl-4-nitropyridine 1 -oxide5-bromo-2 -methylpyridine 1-oxide (2.269 g, 12.07 mmol, 1 eq) was dissolved in sulfuric acid (4 mL, 80 mmol, 6 eq) and cooled at 0 ⁰C. Fuming nitric acid (3 mL, 60 mmol, 5 eq) was added dropwise. After addition of the nitric acid was complete, the reaction mixture was first warmed to room temperature and then heated to 90 ⁰C. After 2 hours the reaction was cooled in an ice bath and slowly adjusted to pH 10 with 2 M aqueous sodium carbonate. This solution was extracted twice with dichloromethane. The combined organic extracts were dried over magnesium sulfate and concentrated to yield 2.54 g (90%) of 5-bromo-2-methyl-4-nitropyridine 1 -oxide. LMCS (ESI) m+H = 233.0.

References:

WO2011/3065,2011,A2 Location in patent:Page/Page column 83-84