The condensation of benzhydryl 7-amino-3-vinyl-3-cephem-4-carboxylate (I) with 4-bromoacetoacetyl bromide (II) by means of trimethylsilylacetamide in ethyl acetate gives benzhydryl 7-(4-bromoaceto-acetamido)-3-vinyl-3-cephem-4-carboxylate (III), which by reaction with NaNO2 - acetic acid in dichloromethane and then with urea is converted to benzhydryl 7-[4-bromo-2-(hydroxyimino)acetoacetamido]-3-vinyl-3-cephem-4 carboxylate (IV). The cyclization of (IV) with thiourea in dimethylacetamide affords benzhydryl 7-[2-(2-aminothiazol-4-yl) (hydroxyimino)acetamido]-3-vinyl-3-cephem-4-carboxylate (V), which is finally hydrolyzed with trifluoroacetic acid - anisole as usual.
The reaction of quinolizidinone (I) with hydroxylamine and pyridine in refluxing ethanol gives the corresponding oxime (II), which is reduced with LiAlH4 in ether to yield 6-methyl-2-aminoquinolizidine (III). The acylation of (III) with 4-acetamido-5-chloro-2-methoxybenzoyl chloride (IV) [prepared from the corresponding acid (V) and SOCl2] by means of triethylamine in benzene affords the protected benzamide (VI), which is finally deprotected with KOH in refluxing ethanol.
The condensation of 2-(2-aminothiazol-4-yl)-2(Z)-(trityoloxyimino)thioacetic acid 2-benzothiazolyl ester (I) with 7-amino-3-vinyl-3-cephem-4-carboxylic acid (II) by means of tributylamine in DMA gives the corresponding amide (III), which is deprotected by means of HCl and formic acid to provide cefdinir.