[C:1]([Br:4])(=[O:3])[CH3:2].[CH3:5][C:6]1[C:11]([CH3:12])=[C:10]([N+]([O-])=[O:14])[CH:9]=[CH:8][N+:7]=1[O-:16].C([O-])([O-])=O.[K+].[K+]>C(O)(=O)C>[C:1]([O-:3])(=[O:14])[CH3:2].[Br:4][C:10]1[CH:9]=[CH:8][N+:7]([OH:16])=[C:6]([CH3:5])[C:11]=1[CH3:12]To a stirred solution of acetyl bromide (67.45 mL, 912.28 mmol) in acetic acid (140 mL) was added 2,3-dimethyl-4-nitro-1-oxido-pyridin-1-ium [TCl](15.34 g, 91.23 mmol) portionwise under nitrogen. The reaction was then warmed to 80° C. for 3 hours. The reaction was cooled and poured into a beaker of ice, and then basified with K2CO3 [caution]. The aqueous was then extracted with EtOAc (600 mL) and the organics were washed with brine (100 mL), dried over MgSO4, filtered and concentrated in vacuo. This gave 4-bromo-1-hydroxy-2,3-dimethyl-pyridin-1-ium acetate (D5)(18.12 g, 65.677 mmol, 72% yield);
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