N-bromobutanimide → Ethyl 3-(bromomethyl)-1-(3-fluoro-2-pyridyl)pyrazole-4-carboxylate
Reaction equation
[F:1][C:2]1[C:3]([N:8]2[CH:12]=[C:11]([C:13]([O:15][CH2:16][CH3:17])=[O:14])[C:10]([CH3:18])=[N:9]2)=[N:4][CH:5]=[CH:6][CH:7]=1.[Br:19]N1C(=O)CCC1=O>ClC1C=CC=CC=1>[Br:19][CH2:18][C:10]1[C:11]([C:13]([O:15][CH2:16][CH3:17])=[O:14])=[CH:12][N:8]([C:3]2[C:2]([F:1])=[CH:7][CH:6]=[CH:5][N:4]=2)[N:9]=1Participants
4
Procedure
To a solution of ethyl 1-(3-fluoro-2-pyridyl)-3-methyl-pyrazole-4-carboxylate (10.2 g, 40.9 mmol) in chlorobenzene (205 mL), N-bromosuccinimide (8 g) is added at room temperature. The reaction mixture is stirred and irradiated under a 100 W lamp at room temperature overnight. Then more N-bromosuccinimide (2 g) is added and after 2 hr., no starting material is detected. Solids are filtered and solvent is evaporated. The crude is purified by normal phase Isco chromatography using as eluent dichloromethane and methanol to give 5.3 g of ethyl 3-(bromomethyl)-1-(3-fluoro-2-pyridyl)pyrazole-4-carboxylate. MS (m/z): 328; 330 (M+1; M+3).