[Na].[OH:2][N:3]=[C:4]([C:8]#[N:9])[C:5]([NH2:7])=[O:6].O.Cl[C:12]([O:14][CH2:15][CH:16]([CH3:18])[CH3:17])=[O:13]>CC(C)=O>[CH2:15]([O:14][C:12]([O:2][N:3]=[C:4]([C:8]#[N:9])[C:5]([NH2:7])=[O:6])=[O:13])[CH:16]([CH3:18])[CH3:17]A mixture of sodium salt of 2-hydroxyimino-2-cyanoacetic acid amide (13.5 g), water (80 ml) and acetone (10 ml) is cooled with ice-water, and isobutyl chloroformate (13.7 g) is dropwise added thereto. The resulting mixture is, after adjusted to pH 7, stirred at a temperature lower than 20°C for 1 hour. The precipitated crystals are collected by filtration and washed with water to give 2-isobutoxycarbonyloxyimino-2-cyanoacetic acid amide (12.3 g). A part of the product is recrystallized from ethyl acetate to obtain crystals melting at 156° to 158°C.
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