合成路线1

2) The condensation of 7-(formamido)-3-(hydroxymethyl)-3-cephem-4-carboxylic acid diphenylmethyl ester (XV) with trichloromethyl chloroformate and dimethylamine in THF gives the corresponding dimethylcarbamoyloxy derivative (XVI), which is hydrolyzed with trifluoroacetic acid and anisole to the corresponding acid (as Na salt) (XVII). The esterification of (XVII) with 1-(isopropoxycarbonyloxy)ethyl iodide (XIV) in DMF as before affords the corresponding ester (XVIII), which is deformylated with HCl in methanol/THF to the 7-amino derivative (XIX). The acylation of (XIX) with 4-bromo-3-oxobutyryl bromide (XX) (obtained from diketene (XXI) with Br2) by means of bis(trimethylsilyl)acetamide in dichloromethane affords the 7-(4-bromo-3-oxobutyramido)-derivative (XXII), which is treated with NaNO2 and acetic acid to obtain the hydroxyimino compound (XXIII). Finally, this compound is cyclized with thiourea in dimethylacetamide. 3) The 7-amino cephem derivative (XIX) can also be acylated with 4-chloro-3-oxobutyryl chloride (XXV) (obtained from diketene (XXI) with Cl2) to yield the 7-(4-chloro-3-oxobutyramido)-derivative (XXVI), which is treated with amyl nitrite and acetyl chloride to afford the hydroxyimino compound (XXVII). Finally, this compound is cyclized with thiourea as before.