反应详情

A solution of t-butyl 3-acetoxymethyl-7β-(2-dichloroacetoxyimino-2-phenylacetamido)-ceph-3-em-4-carboxylate (3.0 g) in trifluoroacetic acid (25 ml.) was allowed to stand at room temperature for ten minutes. The excess acid was removed under reduced pressure, and benzene evaporated from the residue, which was taken up into ethyl acetate and extracted into saturated aqueous sodium bicarbonate. The aqueous phase was washed with ethyl acetate, acidified and extracted with ethyl acetate. The extracts were combined, dried, concentrated to about 5 ml and added dropwise to petroleum (200 ml.). The solid which precipitated was filtered and dried, giving 3-acetoxymethyl-7β-(2-hydroxyamino-2-phenylacetamido)ceph-3-em-4-carboxylic acid (syn-isomer) as a white solid (1.9 g; 88%) [α]D +68° (c 0.8 DMSO), λmax. (EtOH) 254 nm (ε 17,600), νmax. (Nujol) 3380 (NH and OH) 1778 (β-lactam), 1720 (CO2H and acetate), 1666 and 1540 cm-1 (CONH), τ(DMSO-d6) values include 0.32 (doublet, J 9 Hz; NH of syn-isomer), 1.00 (doublet, J 9 Hz; NH of anti-isomer, comprising ca. 10% of the product), 2.15-2.7 (multiplet; aromatic protons), 7.8 (singlet; CH3CO).

1. waitto stand at room temperature for ten minutes
2. customThe excess acid was removed under reduced pressure, and benzene
3. customevaporated from the residue, which
4. extractionextracted into saturated aqueous sodium bicarbonate
5. washThe aqueous phase was washed with ethyl acetate
6. extractionextracted with ethyl acetate
7. customdried
8. concentrationconcentrated to about 5 ml
9. additionadded dropwise to petroleum (200 ml.)
10. customThe solid which precipitated
11. filtrationwas filtered
12. customdried