Trifluoroacetic acid → 7-[2-(2-Aminothiazol-4-yl)-2-methoxyimino-acetamido]-3-vinyl-3-cephem-4-carboxylic acid

Participants

Reaction Steps

To a suspension of benzhydryl 7-[2-(2-aminothiazol-4-yl)-2-methoxyiminoacetamido]-3-vinyl-3-cephem-4-carboxylate (syn isomer)(0.9 g) in methylene chloride (10 ml) and anisole (0.66 g) was added trifluoroacetic acid (2.5 g) under ice-cooling, followed by stirring at ambient temperature for an hour. The reaction mixture was added dropwise to diisopropyl ether (100 ml), and the precipitates were collected by filtration and suspended in a mixture of ethyl acetate and water, followed by adjusting to pH 7 with a saturated aqueous sodium bicarbonate. The separated aqueous solution was saturated with sodium chloride, and thereto was added a mixed solvent of ethyl acetate and tetrahydrofuran (8:2 by volume). After adjusting to pH 3.2 with 10% hydrochloric acid, the organic layer was separated out, washed with a saturated aqueous sodium chloride and then dried over magnesium sulfate. Removal of the solvent gave a residue, which was washed with diisopropyl ether to obtain 7-[2-(2-aminothiazol-4-yl)-2-methoxyiminoacetamido]-3-vinyl-3-cephem-4-carboxylic acid (syn isomer) (0.4 g).

Provenance & Evidence