Diazomethane → Diphenylmethyl (6R-trans)-3-methoxy-8-oxo-7-(phenoxyacetamido)-5-thia-1-azabicyclo(4.2.0)oct-2-ene-2-carboxylate

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Reaction Steps

The resulting crude 7β-phenoxyacetamido-3-hydroxy-ceph-3-em-4-carboxylic acid diphenylmethyl ester is dissolved in methanol and a solution of diazomethane in ether is added at 0° C. After 10 minutes, the solution is carefully concentrated and the residue is dried under a high vacuum. The residue is purified by thick layer chromatography (toluene/ethyl acetate, 3:1, silica gel). After eluting the silica gel of the zone at Rf = 0.17 with ethyl acetate, and concentrating the solution on a rotary evaporator, 7β-phenoxyacetamido-3-methoxy-ceph-3-em-4-carboxylic acid diphenylmethyl ester is obtained; melting point 120° C. (from ether).

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