Hydrochloric Acid → Ethyl 1-(5-chloro-3-fluoropyridin-2-yl)-5-methyl-1H-pyrazole-4-carboxylate

Participants

Reaction Steps

5-Chloro-3-fluoro-2-hydrazinylpyridine (5 g) and ethyl (2-ethoxymethylene)-acetoacetate (5.76 g) synthesized according to the method described in J. Chem. Soc. Perkin trans. I, p. 1875 (1988) were added to a mixed solvent of 1 N hydrochloric acid aqueous solution (150 ml) and ethanol (100 ml), and stirred under reflux. After completion of the reaction, the mixture was allowed to cool, and the organic solvent was evaporated in vacuo. Then, the mixture was extracted with ethyl acetate, the organic layer was dried over anhydrous sodium sulfate, and then the solvent was evaporated in vacuo. The obtained residue was purified with silica gel column chromatography (n-hexane/ethyl acetate) to give 1-(5-chloro-3-fluoropyridin-2-yl)-5-methyl-1H-pyrazole-4-carboxylic acid ethyl ester (6.95 g) as a pale yellow solid. MS (ESI) m/z: 284 (M+H)+.

Provenance & Evidence