Intermediate useful in production of cephem prodrug ester

PURPOSE: To obtain a novel intermediate useful in the synthesis of a cephem prodrug ester which can give an antibiotic in a carboxylic acid form. CONSTITUTION: There is provided a compound comprising a 2-[(Z)-2- aminothiazol-4-yl]-2-(R 2 O-imino)acetic acid of the formula (wherein R 2 is an O-protective group of a type common to the synthesis of a cephalosporin compound), for example, ethyl 2-[(Z)-2-aminothiazol-4-yl]-2-trityloximinoacetate. This compound can be obtained, for example, by reacting ethyl 2-(aminothiazol-4-yl)-2-hydroximinoacetate with trityl chloride in the presence of NaOH in anhydrous tetrahydrofuran at room temperature to obtain an ester and treating this ester with sodium hydroxide at the reflux temperature in aqueous dioxane. COPYRIGHT: (C)1995,JPO