反应详情

A solution of t-butyl 3-acetoxymethyl-7β-[2-dichloroacetoxyimino-(thien-2-yl)acetamido]ceph-3-em-4-carboxylate (syn-isomer) in anisole (20 ml.) was treated with trifluoroacetic acid (100 ml.). After 5 minutes at 20° the solution was concentrated under reduced pressure at 35°. Ethyl acetate was added and the solution was again concentrated, whereupon a solid separated out. Ethyl acetate was evaporated from the residue three more times and the solid was collected and washed with ether to give 3-acetoxymethyl-7β-[2-dichloroacetoxyimino-2-(thien-2-yl)acetamido]ceph-3-em-4-carboxylic acid (syn-isomer) (37 g., 53%) λmax. (ethanol) 263 nm (ε14,800), τ(DMSO-d6) values include -0.19 (doublet, J 8 Hz; NH), 3.02 (singlet, CHCl2), 7.94 (singlet, OCOCH3).

1. concentrationAfter 5 minutes at 20° the solution was concentrated under reduced pressure at 35°
2. additionEthyl acetate was added
3. concentrationthe solution was again concentrated, whereupon a solid
4. customseparated out
5. customEthyl acetate was evaporated from the residue three more times
6. customthe solid was collected
7. washwashed with ether