N[C:2]1[CH:7]=[C:6]([CH3:8])[C:5]([Br:9])=[C:4]([CH3:10])[N:3]=1.[PH2](O)=[O:12].N([O-])=O.[Na+].[OH-].[Na+]>O>[Br:9][C:5]1[C:6]([CH3:8])=[CH:7][C:2](=[O:12])[NH:3][C:4]=1[CH3:10]
To a solution of 2-amino-5-bromo-4,6-dimethylpyridine (0.7 g, 3.48 mmol) in water (6.4 mL) was added an aqueous solution of hypophosphorous acid (50%, 2.9 mL, 27.84 mmol). The mixture was cooled to about 0° C. and a solution of sodium nitrite (0.281 g, 4.07 mmol) in water (1.4 mL) was added with vigorous stirring, maintaining the temperature below 5° C. The mixture was stirred for 30 minutes at 0° C. and was then allowed to warm up to r.t. overnight. The solution was neutralized to pH 6-7 with an aqueous solution of sodium hydroxide (2.0M) and cooled to 5° C. for 5 h. The resulting precipitate was filtered off and washed with cold water. The solid obtained was dried in vacuo to give the title compound (0.681 g, 97%) as a white solid. δH (CDCl3) 6.35 (1H, s), 2.47 (3H, s), 2.29 (3H, s). LCMS (ES+) 201/203 (M+H)+, RT 2.16 minutes (Method 1).
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