反应详情

温度

80 °C

To a solution of acetyl bromide (43.09 mL, 582.81 mmol) in acetic acid (70 mL) was added 2,5-dimethyl-4-nitro-1-oxido-pyridin-1-ium (which may be prepared as described in Description 135) (9.8 g, 58.28 mmol) dropwise over 5 mins. After addition, the mixture was stirred at 80° C. overnight. The reaction mixture was poured on to ice and the solution basified to pH 8 with cold 2M sodium hydroxide. The aqueous layer was extracted with DCM (3x). The combined organics were washed with brine, dried over magnesium sulphate, filtered and evaporated to a pale yellow solid, 4-bromo-2,5-dimethyl-1-oxido-pyridin-1-ium (D136) (12.3 g);

1. additionAfter addition
2. additionThe reaction mixture was poured on to ice
3. extractionThe aqueous layer was extracted with DCM (3x)
4. washThe combined organics were washed with brine
5. dry with materialdried over magnesium sulphate
6. filtrationfiltered
7. customevaporated to a pale yellow solid, 4-bromo-2,5-dimethyl-1-oxido-pyridin-1-ium (D136) (12.3 g)