[Cl:1][C:2]([Cl:21])([Cl:20])[CH2:3][O:4][C:5]([CH2:7][O:8][N:9]=[C:10]([C:16](=O)[CH2:17]Cl)[C:11]([O:13][CH2:14][CH3:15])=[O:12])=[O:6].[NH2:22][C:23]([NH2:25])=[S:24].C([O-])(=O)C.[Na+]>C(O)C.O>[NH2:25][C:23]1[S:24][CH:17]=[C:16]([C:10](=[N:9][O:8][CH2:7][C:5]([O:4][CH2:3][C:2]([Cl:21])([Cl:20])[Cl:1])=[O:6])[C:11]([O:13][CH2:14][CH3:15])=[O:12])[N:22]=1A mixture of ethyl 2-(2,2,2-trichloroethoxycarbonylmethoxyimino)-4-chloro-3-oxobutyrate (20 g), thiourea (3.9 g) and sodium acetate (4.2 g) in ethanol (50 ml) and water (50 ml) was stirred at 40° C. for 5 hours. After removal of the solvent from the reaction mixture, the residue was triturated with diisopropyl ether. The precipitates were collected by filtration and washed with diisopropyl ether to give ethyl 2-(2-aminothiazol-4-yl)-2-(2,2,2-trichloroethoxycarbonylmethoxyimino)acetate (syn isomer) (10.6 g), mp 138°-141° C.
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