Trifluoroacetic acid → 7-Amino-3vinyl-3-cephem-4-carboxylic acid

Participants

Reaction Steps

To a suspension of benzhydryl 7-benzylideneamino-3-vinyl-3-cephem-4-carboxylate (8.6 g) in anisole (10 ml) was added dropwise trifluoroacetic acid (10 ml) at -20° C., and the reaction temperature was gradually raised to ambient temperature with stirring, followed by stirring at ambient temperature for half an hour. The reaction mixture was poured into a mixture of ethyl acetate (100 ml) and a saturated aqueous sodium bicarbonate (100 ml), and then the mixture was adjusted to pH 7.5 with 20% aqueous sodium carbonate. The separated aqueous solution was washed with ethyl acetate (100 ml) and adjusted to pH 7.2 with conc. hydrochloric acid, followed by subjecting to column chromatography on alumina (10 ml). Elution was carried out with 15% aqueous sodium chloride, and fractions containing a desired compound were collected and then adjusted to pH 3.3 with conc. hydrochloric acid. The precipitated crystals were collected by filtration, washed with acetone and dried to obtain 7-amino-3-vinyl-3-cephem-4-carboxylic acid (2.0 g), mp 200°-230° C. (dec.).

Provenance & Evidence