[Br:1][C:2]1[CH:3]=[N:4][C:5]([C:8]([O:10][CH2:11][CH3:12])=[O:9])=[N:6][CH:7]=1.FC(F)(F)C(OC(=O)C(F)(F)F)=[O:16].OO.NC(N)=O>ClCCl>[Br:1][C:2]1[CH:7]=[N:6][C:5]([C:8]([O:10][CH2:11][CH3:12])=[O:9])=[N+:4]([O-:16])[CH:3]=1To a 0° C. cooled solution of 1-ethyl 5-bromopyrimidine-2-carboxylate (2, 1.5 g, 6.5 mmol) in dichloromethane (30 mL), trifluoroacetic anhydride (13.69 g, 65 mmol) and Urea hydrogen peroxide (6.1 g, 65 mmol) were added. The reaction mixture was stirred at room temperature for 16 h. TLC showed consumption of starting material, the reaction mixture was diluted with water (10 mL) and neutralized with solid sodium bicarbonate. The solution was extracted with dichloromethane (2×40 mL). The organic layer was dried over anhydrous sodium sulfate, filtered and concentrated under reduced pressure to afford 5-bromo-2-(ethoxycarbonyl) pyrimidine 1-oxide (3) as yellow liquid which was used without further purification. Yield: 0.64 g, crude; MS (ESI) m/z 247.13 [M+1]+.
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