Potassium Carbonate → methyl 4-(2,5-dimethylpyrimidin-4-yl)-1-methyl-1H-pyrazole-5-carboxylate

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4,4,5,5-Tetramethyl-1,3,2-dioxaborolane (1.5 ml) was added to a 1,4-dioxane (19 ml) solution of methyl 4-bromo-1-methyl-1H-pyrazole-5-carboxylate (1.9 g), 2-dicyclohexylphosphino-2′,6′-dimethoxy-1,1′-biphenyl (0.15 g), Tris(dibenzylideneacetone)dipalladium(0) (0.16 g), and triethylamine (3.7 ml). The obtained mixture was stirred in a nitrogen atmosphere at 100° C. for 30 minutes. Thereafter, 4,4,5,5-tetramethyl-1,3,2-dioxaborolane (1.5 ml) was added to the reaction solution, and the obtained mixture was then stirred for 30 minutes at the same temperature as described above. Thereafter, an aqueous solution (3.9 ml) of potassium carbonate (3.6 g) and a 1,4-dioxane (4 ml) solution of 4-chloro-2,5-dimethylpyrimidine (1.0 g) were successively added to the reaction solution, and the obtained mixture was then stirred at the same temperature as described above for 1 hour. Thereafter, water was added to the reaction solution, and the mixed solution was extracted with ethyl acetate and was then dried over anhydrous sodium sulfate. The solvent was distilled away under reduced pressure, and the obtained residue was purified by silica gel column chromatography (silica gel: eluent; heptane:ethyl acetate=3:1-1:1-0:1), so as to obtain the title compound (1.9 g) in the form of an orange liquid.

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