Hydrochloric Acid → Methyl [2-(1-(4-chlorophenyl)-3-pyrazolyloxy)pyridin-3-yl]glyoxylate

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Reaction Steps

At 60° C., 4.7 g (42 mmol) of potassium tert-butoxide were added a little at a time to a solution of 7.4 g (38.1 mmol) of 1-(4-chlorophenyl)-3-hydroxypyrazole in 15 ml of tert-butanol. The mixture was stirred at this temperature for 1 hour and the solvent was then removed under reduced pressure. The residue was dissolved in 25 ml of abs. dimethyl sulfoxide, and a solution of 8.0 g (38.1 mmol) of methyl (2-chloropyridin-3-yl)glyoxylate in 10 ml of abs. dimethyl sulfoxide was then added at such a rate that the temperature did not exceed 30° C. After 30 minutes at room temperature, 50 ml of 0.5 N HCl were added and the reaction mixture was extracted repeatedly with ethyl acetate. The combined organic phases were washed with water and dried over sodium sulfate. The solvent was subsequently removed under reduced pressure. The resulting residue was purified by silica gel column chromatography using cyclohexane/ethyl acetate (10:1) as eluant. 5.5 g (40%) of the title compound were obtained as a clear oil.

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