Hydrochloric Acid → 2-(2-Formamido-5-chlorothiazol-4-yl)-2-propargyloxyiminoacetic acid

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Reaction Steps

A solution of chlorine (3.2 g) in acetic acid (44 ml) was added dropwise to a solution of 2-(2-propynyloxyimino)-2-(2-formamidothiazol-4-yl)acetic acid (syn isomer)(10 g) in chloroform (250 ml) at 0° C. and the mixture was stirred for 30 minutes at the same temperature. The resulting solution was added to a saturated aqueous sodium bicarbonate and the mixture was adjusted to pH 7.5 with 10% aqueous sodium hydroxide. The separated aqueous layer was adjusted to pH 2.0 with conc. hydrochloric acid and extracted with ethyl acetate. The extracts were washed with a saturated aqueous sodium chloride, dried over magnesium sulfate and evaporated. The residue was washed with diisopropyl ether and filtered to give 2-(2-propynyloxyimino)-2-(2-formamido-5-chlorothiazol-4-yl)acetic acid (syn isomer)(5.96 g), mp 161°-162° C. (dec.).

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