C[O-].[Na+].[CH2:4]([C:8]([NH2:10])=[O:9])[C:5]([NH2:7])=[O:6].C(O[CH:14]=[CH:15][C:16](=O)[C:17]([F:20])([F:19])[F:18])C.Cl>CO>[O:6]=[C:5]1[C:4]([C:8]([NH2:10])=[O:9])=[CH:14][CH:15]=[C:16]([C:17]([F:20])([F:19])[F:18])[NH:7]1
Sodium methoxide (74 g, 1.37 mol) was dissolved in methanol (1,000 mL), and malon diamide (100 g, 0.979 mol) was added to this solution at room temperature. To this mixture, 4-ethoxy-1,1,1-trifluoro-3-buten-2-one (191 g, 1.14 mol) was added dropwise at a temperature between 25 and 30° C., and the resultant mixture was refluxed under heating for 2 hours. After cooling to 45° C., concentrated hydrochloric acid was added to the mixed solution to give a pH of 3 to 4, and 500 mL of methanol was distilled off at normal pressure. To the residue, water (500 mL) was added, and the mixture was stirred for a day at room temperature. The resultant product was precipitated while cooling with ice. Thus obtained crystal was collected by filtration, washed with water, and then dried under reduced pressure, to obtain 167 g of a subject compound (yield: 83%).
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