Acetyl chloride → Diphenylmethyl 7-(2-thienylacetamido)-3-(1-acetoxyethyl)-3-cephem-4-carboxylate

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Reaction Steps

To a solution of non-polar stereoisomer A of diphenylmethyl 7-(2-thienylacetamido)-3-(1-acetoxyethyl)-3-cephem-4-carboxylate 1-oxide (85 mg) in N,N-dimethylformamide (2.5 ml) is added under ice cooling stannous chloride dihydrate (81 mg) with stirring. Ten minutes after the addition of acetyl chloride (0.34 mg), the mixture is stirred with ice for 20 minutes. The reaction mixture is poured into ice water, and is extracted with ethyl acetate. The extract solution is washed with aqueous sodium hydrogen carbonate and saline, dried over sodium sulfate, and evaporated. Recrystallization of the residue (81 mg) from petroleum ether gives the stereoisomer A of diphenylmethyl 7-(2-thienylacetamido)-3-(1-acetoxyethyl)-3-cephem-4-carboxylate (66 mg). m.p. 77°-85° C. Yield: 79.8%. IR: νmaxCHCl 3 3405, 1789, 1728, 1685, 1509 cm-1. NMR: δCDCl 3 1.34d(6.5Hz)3H, 1.98s3H, 3.37s2H, 3.82s2H, 4.96d(5Hz)1H, 5.79q (8.5;5Hz)1H, 5.99q(6.5Hz)1H, 6.32d(8.5Hz)1H, 6.8-7.5m14H.

Provenance & Evidence