[CH2:1]([O:3][N:4]=[C:5]([C:9]1[N:13]=[C:12]([NH:14]C=O)[S:11][N:10]=1)[C:6]([OH:8])=[O:7])[CH3:2].[OH-].[Na+].Cl>C(OCC)(=O)C>[CH2:1]([O:3][N:4]=[C:5]([C:9]1[N:13]=[C:12]([NH2:14])[S:11][N:10]=1)[C:6]([OH:8])=[O:7])[CH3:2]A mixture of 2-ethoxyimino-2-(5-formamido-1,2,4-thiadiazol-3-yl)acetic acid (syn isomer) (4.4 g) and 1 N aqueous solution of sodium hydroxide (54 ml) was stirred for 2 hours at 50° to 55° C. The mixture was cooled in an ice bath, acidified with hydrochloric acid (5.4 ml) and extracred with ethyl acetate. The extract was dried over magnesium sulfate and evaporated to dryness. The residue was triturated with diethyl ether to give 2-ethoxyimino-2-(5-amino-1,2,4-thiadiazol-3-yl)acetic acid (syn isomer) (2.92 g), mp. 168° to 170° C. (dec.).
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