Diethyl Ether → 2-(1H-Pyrazol-3-Yl)Pyridine

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8.88 g of 3-(3,5-dichloro-2-pyridyl)-5-trifluoromethyl-[1H]-pyrazole (Example P10) are introduced into 35 ml of N-methylpyrrolidone. After the addition of 13.0 g of potassium carbonate, the mixture is stirred and heated to 55° C. 2.36 ml of methyl iodide in 5.0 ml of N-methylpyrrolidone are then slowly added dropwise. After subsequently stirring for 2 hours, diethyl ether and water are added, the mixture is extracted by shaking and the organic phase is separated off. The separated ethereal phase is washed with brine, dried over sodium sulfate, filtered and concentrated. The crude product is purified by means of flash chromatography (silica gel; eluant: toluene/ethyl acetate 100/1). First of all 3.96 g of the 5-pyridylpyrazole isomer (yield 42%) are isolated in the form of a yellow oil and then 1.96 g of the 3-pyridylpyrazole (yield 21%) are isolated in the form of a yellow solid. The Rf values of the 3- and 5-pyridylpyrazole isomers on silica gel 60 F254 using toluene/ethyl acetate 30/1 as eluant (UV) are:

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