反应详情

A solution of 1.275 g of 7β-phenylacetylamino-ceph-3-em-4-carboxylic acid in 5 ml of methanol and 20 ml of dioxane is treated with an excess of diphenyldiazomethane and allowed to stand at room temperature. The red-coloured reaction mixture is treated with a small amount of acetic acid and then evaporated to dryness under reduced pressure. The oily yellowish residue is taken up in a small amount of methylene chloride, the solution is treated with diethyl ether at an elevated temperature. The colourless precipitate (felt-like needles) is filtered off, washed with diethyl ether, then with pentane and dried to yield the 7β-phenylacetylamino-ceph-3-em-4-carboxylic acid diphenylmethylester of the formula ##STR28## m.p. 163.5°-164.5°; [α]D20 =+30°±1° (c=0.968 in dioxane); thin-layer chromatogram (silica gel): Rf=0.55 (system: toluene/acetone 4:1), Rf=0.35 (system: toluene/acetone 9:1) and Rf=0.40 (system: toluene/ethyl acetate 4:1); ultraviolet absorption spectrum: λmax =258 mμ (ε=6100) and λmin =240 mμ (ε=5250) (in methylene chloride) and λmax =259 mμ (ε=6050) and λmin =239 mμ (ε=4950); (95% ethanol) infrared absorption spectrum: characteristic bands at 2.90μ, 5.57μ, 5.76μ, 5.91μ, 6.09μ, 6.66μ, 7.13μ, 8.12μ, 8.63μ, 9.07μ, 10.43μ and 12.22μ (in methylene chloride) and at 3.01μ, 5.60μ, 5.82μ, 6.04μ, 6.08μ (shoulder), 6.51μ and 7.13μ (in mineral oil).

1. customto stand at room temperature
2. customevaporated to dryness under reduced pressure
3. additionthe solution is treated with diethyl ether at an elevated temperature
4. filtrationThe colourless precipitate (felt-like needles) is filtered off
5. washwashed with diethyl ether
6. dry with materialwith pentane and dried