C([Li])CCC.CCCCCC.Br[C:13]1[C:14]([O:23][CH3:24])=[N:15][CH:16]=[N:17][C:18]=1[C:19]([F:22])([F:21])[F:20].[CH:25](OCC)=[O:26]>O1CCCC1.O>[CH3:24][O:23][C:14]1[C:13]([CH:25]=[O:26])=[C:18]([C:19]([F:22])([F:21])[F:20])[N:17]=[CH:16][N:15]=1
30.0 ml of n-butyllithium (a 1.6 moles/liter n-hexane solution, 48.0 mmoles) was gradually added, at −65 to −60° C., to a solution of 10.3 g (40.0 mmoles) of 5-bromo-4-methoxy-6-trifluoromethylpyrimidine dissolved in 100 ml of tetrahydrofuran. The mixture was stirred for 30 minutes. Thereto was added 3.6 g (48.0 mmoles) of ethyl formate at the same temperature. The resulting mixture was stirred at the same temperature for 3 hours to give rise to a reaction. The reaction mixture was poured into water, followed by extraction with ethyl acetate. The resulting organic layer was washed with water and an aqueous sodium chloride solution in this order and then dried over anhydrous magnesium sulfate. The resulting solution was subjected to vacuum distillation to remove the solvent contained therein. The residue was purified by silica gel column chromatography to obtain 1.3 g (yield: 15.8%) of 4-methoxy-6-trifluoromethylpyrimidine-5-carboaldehyde.
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