Triethylamine → (6R)-8-Oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylic acid

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Reaction Steps

Following the procedure described in Example 1, a solution of the appropriate 2-aryl-2-t-butoxycarbonyl-Rq -oxyiminoacetic acid (syn-isomer) (1 equiv) in methylene chloride optionally containing a few drops of N,N-dimethylformamide and triethylamine (1 equiv) was treated with oxalyl chloride (1 equiv) at 0°-5° for ca. 1 hour. The mixture was then evaporated to dryness. The residue was suspended or dissolved in acetone and added to a stirred, ice-cold solution of (6R,7R)-3-acetoxymethyl-7-aminoceph-3-em-4-carboxylic acid (1-1.2 equiv) in water or a mixture of acetone and water containing sodium hydrogen carbonate (2-2.5 equiv). The reaction mixture was stirred for 0.5-2.5 hours, allowing the temperature to rise to room temperature, whereafter the acetone was removed under reduced pressure. The pH was adjusted to 1.5- 2.0 and the product extracted into ethyl acetate (alternatively ether or methylene chloride may be used). The organic layer was washed with water and/or saturated brine, dried and evaporated to give the corresponding (6R,7R)-3-acetoxymethyl-7-(2-aryl-2-t-butoxycarbonyl-R q -oxyiminoacetamido)ceph-3-em-4-carboxylic acid (syn-isomer) which was characterised by optical rotation and/or by spectroscopy.

Provenance & Evidence