合成路线1

The protection of the amino group of ethyl 2-(2-amino-4-thiazolyl)-2-methoxyiminoacetate (I) with trityl chloride (B) by means of triethylamine in CH2Cl2 gives ethyl 2-(2-tritylamino-4-thiazolyl)-2-methoxyimino acetate (II), which is hydrolyzed to the corresponding acid (III) with NaOH in refluxing dioxane-water. The condensation of (III) with 7-aminocephalosporanic acid (IV) by means of dicyclohexylcarbodiimide in CH2Cl2 containing triethylamine affords 7-(2-(2-tritylamino-4-thiazolyl)-2-methoxyiminoacetamido]cephalosporanic acid (V). The elimination of the trityl group is performed with hot 55% formic acid yielding the corresponding free acid, which is finally treated with NaHCO3 in water.

合成路线2

The methylation of ethyl 3-oxo-2-hydroxyiminobutyrate (I) with dimethyl sulfate and Na2CO3 in methanol gives ethyl 3-oxo-2-methoxyiminobutyrate (II), which is brominated with Br2 in CHCl3 to afford ethyl 4-bromo-3-oxo-2-methoxyiminobutyrate (III). The cyclization of (III) with thiourea (A) in refluxing ethanol affords ethyl 2-(2-aminothiazol-4-yl)-2-methoxyiminoacetate (IV), which is acylated with chloroacetyl chloride in dimethylacetamide to yield ethyl 2-(2-chloroacetamidothiazol-4-yl)-2-methoxyiminoacetate (V). The hydrolysis of (V) with KOH in ethanol-water gives the corresponding free acid (VI), which is treated with PCl5 in methylene chloride to obtain the acyl chloride (VII). The condensation of tert-butyl 7-aminocephalosporanate (VIII) with (VII) by means of pyridine in methylene chloride gives tert-butyl 7-[alpha-methoxyimino-(2-chloroacetamidothiazol-4-yl)acetamido]cephalosporanate (IX), which is desacylated with thiourea and triethylbenzylammonium bromide in THF-ethanol yielding tert-butyl 7-[alpha-methoxyimino-alpha-(2-aminothiazol-4-yl)acetamido]cephalosporanate (X), which is hydrolyzed with trifluoroacetic acid to afford the free cephalosporanic acid (Xl). Finally, this compound is condensed with 1-methyl-5-mercaptotetrazol (XII) by means of NaHCO3 and triethylbenzylammoniurn bromide in water.

合成路线3

The methylation of ethyl 2-(hydroxyimino)-3-oxobutyrate (I) with dimethyl sulfate and Na2CO3 in methanol gives ethyl 2-(methoxyimino)-3-oxobutyrate (II), which is brominated with Br2 in CHCl3 yielding ethyl 4-bromo-2-(methoxyimino)-3-oxobutyrate (III). The cyclization of (III) with thiourea (IV) in refluxing ethanol affords ethyl 2-(2-aminothiazol-4-yl)-2-(methoxyimino)acetate (V), which is acylated with chloroacetyl chloride (VI) in DMA to give the corresponding N-chloroacetyl derivative (VII). The hydrolysis of (VII) with KOH in ethanol-water affords 2-(2-chloroacetamidothiazol-4-yl)-2-(methoxyimino)acetic acid (VIII), which is condensed with desacetoxycephalosporanic acid (IX) by means of N-hydroxysuccinimide (NOHS) and dicyclohexylcarbodiimide (DCC) in THF yielding 7beta-[2-(2-chloroacetamidothiazol-4-yl)-2(Z)-(methoxyimino)acetamido]desacetoxycephalosporanic acid (X). The deprotection of (X) with sodium acetate in THF gives the free acid (XI), which is finally esterified with pivaloyloxymethyl bromide (XII) by means of NaHCO3 in ethyl acetate-DMSO.

合成路线4

The reaction of ethyl acetoacetate (I) with NaNO2 in acetic acid-water gives ethyl 2-(hydroxyimino)-3-oxobutyrate (II), which is cyclized with thiourea (III) by means of SO2Cl2 in methylene chloride yielding ethyl 2-(2-aminothiazol-4-yl)-2-(hydroxyimino)acetate (IV). The treatment of (IV) with trityl chloride (V) and triethylamine in DMF affords ethyl 2-(hydroxyimino)-2-(2-tritylaminothiazol-4-yl)acetate (VI), which by condensation with tert-butyl 2-bromo-2-methylpropionate (VII) by means of K2CO3 in DMSO is converted into ethyl 2-(2-tert-butoxycarbonyl-2-propyloxymino)-2-(2-tritylaminothiazol-4-yl)acetate (VIII). The hydrolysis of (VIII) with NaOH in refluxing methanol gives 2-(2-tert-butoxycarbonyl-2-propyloxyimino)-2-(2-tritylaminothiazol-4-yl)acetic acid (IX), which by condensation with tert-butyl 7-aminocephalosporanate (X) by means of 1-hydroxybenzotriazole and dicyclohexylcarbodiimide in DMF yields tert-butyl 7-[2-(2-tert-butoxycarbonyl-2-propyloxyimino)-2-(2-tritylaminothiazol-4-yl)acetamido]cephalosporanate (XI). The hydrolysis of (XI) with trifluoroacetic acid in anisole affords 7-[2-(2-aminothiazol-4-yl)-2-(2-carboxy-2-propyloxyimino)acetamido]cephalosporanic acid (XII), which is finally treated with pyridine (A) and NaI.

合成路线5