N-bromobutanimide → Ethyl 3-(bromomethyl)-1-(3-fluoro-2-pyridyl)pyrazole-4-carboxylate

Participants

Reaction Steps

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).

Provenance & Evidence