Cefmenoxime is a third-generation cephalosporin antibiotic.
Synthesis
The
alkylation of ethyl 2-hydroxyimino-3-oxobutanoate (1) with
dimethylsulfate gives ethyl (2Z)-2-methoxyimino-3-oxo-butanoate (2).
Halogenation with molecular bromine leads to ethyl 4-bromo-2-methoxyimino-3-oxobutanoate (3). Treatment with
thiourea gives ethyl (Z)-2-(2-amino-4-thiazolyl)-2-methoxyiminoacetate (4) which is reacted with chloroacetyl chloride to give the
amide (5).
Saponification with potassium hydroxide gives (6) which is halogenated with phosphorus pentachloride to (7). Amide formation with the
cephalosporin intermediate (8) then gives (9). Removal of the
protecting group with benzyltriethylammonium bromide yields (10). The tert-butyl
ester was deprotected with trifluoroacetic acid to give (11). Lastly,
thioether formation with 5-mercapto-1-methyltetrazole (12) completes the synthesis of cefmenoxime.
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Further reading
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