7-Acylamino and 7-amino-3-(substituted)carbonylamino-3(or 2)-cephem-4-carboxylic acids and esters thereof, which are useful as antibiotics or as intermediates in preparing antibiotic substances respectively, are prepared from 7-acylamino-3-azidocarbonyl-2(or 3)-cephem-4-carboxylic acid esters via the corresponding thermally derived 3-isocyanatocephem derivatives.
7-酰胺基和7-
氨基-3-(取代基)羧酰胺基-3(或2)-头孢-4-
羧酸及其
酯类是有用的抗生素或抗生素物质的中间体,它们通过相应的热导出的3-异
氰酸基头孢-4-
羧酸酯类从7-酰胺基-3-偶氮基羧酰基-2(或3)-头孢-4-
羧酸酯类制备而成。