[Br:1][C:2]1[CH:6]=[CH:5][NH:4][N:3]=1.Cl[C:8]1[C:13]([Cl:14])=[CH:12][CH:11]=[CH:10][N:9]=1.C(=O)([O-])[O-].[Cs+].[Cs+].CN(C)C=O>O>[Br:1][C:2]1[CH:6]=[CH:5][N:4]([C:8]2[C:13]([Cl:14])=[CH:12][CH:11]=[CH:10][N:9]=2)[N:3]=1
A mixture of 10.7 g of 3-bromo-1H-pyrazole, 11.8 g of 2,3-dichloropyridine, 57.3 g of cesium carbonate and 80 ml of N,N-dimethylformamide was stirred at 100° C. for 8 hours. The reaction mixture was allowed to cool to room temperature. After water was added, and the reaction mixture was extracted with methyl tert-butyl ether two times. The organic layers were combined, washed with sequentially with water and a saturated solution of sodium chloride, dried over magnesium sulfate, and concentrated under reduced pressure. The resulting residue was subjected to silica gel column chromatography to obtain 12.9 g of 2-(3-bromo-1H-pyrazol-1-yl)-3-chloropyridine.
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