Trifluoroacetic acid → 7-[2-(5-amino-1,2,4-thiadiazol-3-yl)-2-carboxymethoxyiminoacetamido]-3-[(Z)-2-(3-pyridyl)vinylthio]-3-cephem-4-carboxylic acid

Participants

Reaction Steps

To a solution of benzhydryl 7-[2-(5-amino-1,2,4-thiadiazol-3-yl)-2-carboxymethoxyiminoacetamido]-3-[(Z)-2-(3-pyridyl)vinylthio]-3-cephem-4-carboxylate (syn isomer) (1.28 g) in a mixture of methylene chloride (3.8 ml) and anisole (1.28 ml) was added trifluoroacetic acid (2.6 ml) under ice-cooling. The mixture was stirred for 45 minutes at the same temperature The mixture was poured into diisopropyl ether (200 ml) to give a precipitate. The precipitate was collected, washed with diisopropyl ether and dissolved in a mixture of ethyl acetate and dilute aqueous solution of sodium bicarbonate at pH 5. The insoluble material was filtered off. The aqueous layer was separated and concentrated in vacuo in order to remove ethyl acetate. The aqueous solution was adjusted to pH 4.5 with dilute hydrochloric acid, subjected to column chromatography on macroporous non-ionic adsorption resin "Diaion HP-20" (20 ml) and eluted with water. The fractions containing the object compound were combined and concentrated in vacuo to about 20 ml. The concentrated solution was adjusted to pH 2 with dilute hydrochloric acid under ice-cooling to give a precipitate. The precipitate was collected, washed with cold water and dried over phosphorus pentoxide to give 7-[2-(5-amino-1,2,4-thiadiazol-3-yl)-2-carboxymethoxyiminoacetamido]-3-[(Z)-2-(3-pyridyl)vinylthio]-3-cephem-4-carboxylic acid (syn isomer) (220 mg).

Provenance & Evidence