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

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Reaction Steps

Ethyl (2-formamido-5-chlorothiazol-4-yl)glyoxylate (14.5 g) was added to a solution of 1 N aqueous potassium hydroxide (110 ml) at ambient temperature, and the mixture was stirred for 10 minutes to prepare the solution of potassium (2-formamido-5-chlorothiazol-4-yl)glyoxylate. After this solution was adjusted to pH 2 with 10% hydrochloric acid under ice-cooling, thereto were added pyridine (20 ml) and a solution of tert-butyl 2-aminooxyacetate (10.3 g) in tetrahydrofuran (50 ml), followed by stirring at ambient temperature for 5 hours. After the reaction mixture was washed with ethyl acetate, the remaining aqueous solution was adjusted to pH 1.5 with 10% hydrochloric acid and extracted with ethyl acetate. The extract was washed with an aqueous sodium chloride and then dried over magnesium sulfate. Removal of the solvent gave 2-tert-butoxycarbonylmethoxyimino-2-(2-formamido-5-chlorothiazol-4-yl)acetic acid (syn isomer) (8.5 g).

Provenance & Evidence