[CH3:1][C:2]1[CH:6]=[C:5]([C:7]([O:9][CH2:10][CH3:11])=[O:8])[NH:4][N:3]=1.CS(O[CH2:17][CH:18]1[CH2:20][CH2:19]1)(=O)=O.C(N(CCCC)CCCC)CCC>C(OCC)C>[CH:18]1([CH2:17][N:4]2[C:5]([C:7]([O:9][CH2:10][CH3:11])=[O:8])=[CH:6][C:2]([CH3:1])=[N:3]2)[CH2:20][CH2:19]1A mixture comprising 3.8 g of ethyl 3-methyl-1H-pyrazole-5-carboxylate, 3.8 g of cyclopropylmethyl methanesulfonate and 4.6 g of tri-n-butylamine was allowed to react at 110 ° C. for three hours without using any solvent. Then the reaction mixture was allowed to cool and diethyl ether was added thereto. The obtained mixture was successively washed with 1 N hydrochloric acid, an aqueous solution of sodium hydrogencarbonate and a saturated aqueous solution of common salt and then dried over anhydrous sodium sulfate. The solvent was distilled off under reduced pressure and the obtained residue was purified by column chromatography (eluent: hexane:ethyl acetate=14 : 1). Thus 0.62 g of the aimed ethyl 1-cyclobutyl-3-methyl-1H-pyrazole-5-carboxylate (compound No. 1001) (yield: 12.1 %) and 2.45 g of ethyl 1-cyclopropylmethyl-3-methyl-1H-pyrazole-5-carboxylate (yield: 54.3 %) were obtained.
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