General procedure for the synthesis of 5-bromo-1-methyl-1H-1,2,4-triazole from 1-methyl-1H-1,2,4-triazole: 1.6 M n-BuLi (8.70 mL, 13.86 mmol) was slowly added to a mixed solution of 1-methyl-1H-1,2,4-triazole (1.0 mL, 13.20 mmol) and THF (100 mL) at -78 °C. 13.86 mmol). After 45 min of reaction, 1,2-dibromo-1,1,2,2-tetrafluoroethane (1.76 mL, 14.52 mmol) was added, and then the reaction mixture was slowly warmed to room temperature and stirring was continued for 2 hours. After completion of the reaction, the reaction solution was diluted with EtOAc (200 mL), washed sequentially with water (150 mL) and brine (150 mL), the organic phase was dried with MgSO4, filtered and concentrated to afford 5-bromo-1-methyl-1H-1,2,4-triazole (1.37 g, 8.46 mmol, 64% yield). The product was confirmed by 1H NMR (CDCl3): δ 3.82 (s, 3H), 7.78 (s, 1H). LC/MS analysis showed that the m/z calculated value [C3H4BrN3(M+H)+] was 162.0 and the measured value was 161.9.
