Phosphorus trichloride → 4-Nitrobenzyl 7-[2-(2-thienyl)acetamido]-3-chloro-3-cephem-4-carboxylate

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Reaction Steps

Alternatively, the 3-hydroxy-3-cephem esters prepared via the reduction of a sulfoxide compound of the formula I can be reacted with phosphorus trichloride is DMF to effect chlorination of the 3-hydroxy group and provide a 3-chloro-3-cephem ester. For example, 4-nitrobenzyl 7-[2-(2-thienyl)acetamido]-3-hydroxy-3-cephem-4-carboxylate is reacted with phosphorus trichloride in DMF to yield 4-nitrobenzyl 7-[2-(2-thienyl)acetamido]-3-chloro-3-cephem-4-carboxylate. Cleavage of the 4-nitrobenzyl ester group provides the antibiotic compound 7-[2-(2-thienyl)acetamido]-3-chloro-3-cephem-4-carboxylic acid. These 3-halo-3-cephem antibiotics are likewise fully disclosed in my copending applications Ser. Nos. 457,150 and 457,153 filed Apr. 1, 1974 the latter now U.S. Pat. No. 3,925,372 issued Dec. 9, 1975.

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