Hydrochloric Acid → 2-Methyl-7-[2-methoxyimino-2-(2-aminothiazol-4-yl)acetamido]-3-cephem-4-carboxylic acid

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To a suspension of 2-methyl-7-[2-methoxyimino-2-(2-aminothiazol-4-yl)acetamido]-3-cephem-4-carboxylic acid hydrochloride (syn isomer), which can be represented as 2-methyl-7-[2-methoxyimino-2-(2-imino-2,3-dihydrothiazol-4-yl)acetamido]-3-cephem-4-carboxylic acid hydrochloride (syn isomer), (7.7 g.) in water (77 ml.) was added a saturated aqueous sodium bicarbonate solution (44 ml.). Thus obtained solution was adjusted to pH 3 with 1N hydrochloric acid and then allowed to stand for 1 hour at cold place. The precipitated crystals were collected by filtration, washed with water and then dried to give white powder of 2-methyl-7-[2-methoxyimino-2-(2-aminothiazol-4-yl)acetamido]-3-cephem-4-carboxylic acid (syn isomer), which can be represented as 2-methyl-7-[2-methoxyimino-2-(2-imino-2,3-dihydrothiazol-4-yl)acetamido]-3-cephem-4-carboxylic acid (syn isomer) (6.67 g.), mp 196° to 240° C. (dec.).

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