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 H11) are initially introduced into 35 ml of N-methylpyrrolidone. After addition of 13.0 g of potassium carbonate, the mixture is stirred and heated up to 55° C. 2.36 ml of methyl iodide in 5.0 ml of N-methylpyrrolidone are then slowly added dropwise. After the mixture has been subsequently stirred for 2 hours, diethyl ether and water are added, the mixture is extracted by shaking and the organic phase is separated off. The ether phase which has been separated off is washed with brine, dried over sodium sulfate, filtered and concentrated. The crude product is purified by means of flash chromatography (silica gel; eluting agent: toluene/ethyl acetate 100/1). First, 3.96 g of the isomeric 5-pyridylpyrazole (yield 42%) are isolated as a yellow oil, and then 1.96 g of the 3-pyridylpyrazoie (yield 21%) are isolated as a yellow solid. The Rf values of the two isomeric 3- and 5-pyridyipyrazoles are as follows on silica gel 60 F254 with toluenelethyl acetate 30/1 as the eluting agent (UV):

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