Sodium Hydroxide → 2-Methoxyimino-2-(1,2,3-thiadiazol-4-yl)acetic acid

A solution of sodium hydroxide (0.47 g.) in water (10 ml.) was added to a solution of ethyl 2-methoxyimino-2-(1,2,3-thiadiazol-4-yl)acetate (anti isomer) (2.1 g.) in methanol (20 ml.) and the resulting mixture was stirred for 6 hours at ambient temperature. Methanol was removed from the reaction mixture and to the residue was added water. The resulting mixture was washed with ether, adjusted to pH 1 with 10% hydrochloric acid and extracted twice with ether (50 ml.). The extract was washed with a saturated aqueous solution of sodium chloride and dried over magnesium sulfate. The solvent was distilled off to give oil of 2-methoxyimino-2-(1,2,3-thiadiazol-4-yl)acetic acid (anti isomer) (1.3 g.).