Phosphorus pentachloride → (6R,7R)-7-[[(2Z)-2-(5-amino-1,2,4-thiadiazol-3-yl)-2-methoxyiminoacetyl]amino]-8-oxo-3-(3-oxobutanoyloxymethyl)-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylic acid

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Reaction Steps

In 240 ml of dichloromethane is suspended 9.06 g of 7β-amino-3-(3-oxobutyryloxymethyl)-3-cephem-4-carboxylic acid. To the suspension is added 28.9 g of bistrimethylsilylacetamide and the mixture is stirred at room temperature until complete dissolution and cooled in an ice-water bath. To this solution, 2-(5-amino-1,2,4-thiadiazol-3-yl)-2(Z)-methoxyiminoacetyl chloride hydrochloride prepared from 5.83 g of 2-(5-amino-1,2,4-thiadiazol-3yl)-2(Z)-methoximinoacetic acid and 6.02 g of phosphorus pentachloride in 90 ml of dischloromelthane is added and the mixture is stirred for a while. The whole mixture is stirred with ice-cooling for 60 minutes. The dichloromethane is evaporated off and the residue is dissolved in melthyl ethyl ketone. The solution is washed with water and dried. The solvent is then evaporated off and diethyl ether is added to the residue to give a fine precipiate, which is collected by filtration, giving 11.8 (82% yield) g of the title compound.

Provenance & Evidence