反应详情

温度

0 °C

A solution, cooled to 0° C., of 2.0 g of 7β-phenylacetylamino-cepham-3-one-4ξ-carboxylic acid diphenylmethyl ester in 75 ml of methanol is treated with excess diazo-n-butane in diethyl ether. The mixture is stirred for 15 minutes at 0° C. and is then evaporated under reduced pressure. The oily residue is purified by means of preparative thin layer chromatography (silica gel plates, 6×100 cm; system: toluene/ethyl acetate, 3:1). The layer which is visible under ultraviolet light (λ=254 mμ) is removed and in each case eluted with acetone. This zone (Rf~0.33) yields 3-n-butoxy-7β-phenylacetylamino-3-cephem-4-carboxylic acid diphenylmethyl ester which after crystallisation from a mixture of methylene chloride and diethyl ether is in the form of colourless flakes which melt at 168°-170° C., [α]D20 =+55°±1° (c=0.38 in chloroform); ultraviolet absorption spectrum (in 95% strength aqueous ethanol): λmax =264 mμ (ε=7,300); infrared absorption spectrum (in methylene chloride): characteristic bands at 2.98μ, 5.62μ, 5.81μ, 5.92μ, 6.25μ and 6.62μ.

1. customis then evaporated under reduced pressure
2. customThe oily residue is purified by means of preparative thin layer chromatography (silica gel plates, 6×100 cm; system: toluene/ethyl acetate, 3:1)
3. customis removed and in each case
4. washeluted with acetone