反应详情

A mixture of 0.312 g of 3ξ-hydroxy-7β-phenylacetylamino-cepham-4ξ-carboxylic acid diphenylmethyl ester in 15 ml of pyridine and 7 ml of acetic anhydride is left to stand for 16 hours at 0° C. and after addition of 50 ml of toluene is evaporated under reduced pressure. The residue is taken up in ethyl acetate; the organic solution is washed with a saturated aqueous sodium bicarbonate solution and a saturated aqueous sodium chloride solution, dried over sodium sulphate and evaporated under reduced pressure. The residue is purified by means of preparative thin layer chromatography; a silica gel plate of 100 cm length is used and development is carried out with a 1:1 mixture of toluene and ethyl acetate. 3ξ-Acetoxy-7β-phenylacetylaminocepham-4α-carboxylic acid diphenylmethyl ester of Rf=0.47 is obtained, melting at 162°-164° C. after crystallization from a mixture of methylene chloride and pentane; [α]D20 =+55°±1° (c=0.492 in chloroform); ultraviolet absorption spectrum (in 95% strength ethanol): λmax =253 mμ (ε=700), 258 mμ(ε=820) and 265 mμ (ε=660); infrared absorption spectrum (in methylene chloride): characteristic bands at 2.96μ, 5.66μ, 5.77μ, 5.97μ, 6.28μ and 6.71μ.

1. waitis left
2. customis evaporated under reduced pressure
3. washthe organic solution is washed with a saturated aqueous sodium bicarbonate solution
4. dry with materiala saturated aqueous sodium chloride solution, dried over sodium sulphate
5. customevaporated under reduced pressure
6. customThe residue is purified by means of preparative thin layer chromatography
7. additiondevelopment is carried out with a 1:1 mixture of toluene and ethyl acetate