反应详情

A mixture of 103.2 g of dicyclohexylcarbodiimide, 43.5 g of t-butyl alcohol and 1.1 g of cuprous chloride was held at room temperature for 3 days and the mixture was then dissolved in 200 ml of methylene chloride. The resulting solution was added dropwise to a suspension of 35 g of 7-benzamido-3-methyl-3-cephem-4-carboxylic acid-1-oxide in 500 ml of methylene chloride and after stirring for 24 hours at room temperature, the precipitated N,N'-dicyclohexyl urea was removed by filtration and the precipitate washed with methylene chloride. The combined filtrates were washed sequentially with 2 N hydrochloric acid, saturated sodium bicarbonate solution (three times) and with water (twice). Methylene chloride was removed by evaporation in vacuo and toluene was added to the residue. The crystalline solid was isolated by filtration and washed with toluene. Upon crystallization from a methylene chloride/toluene mixture, 19.6 g (48% yield) of t-butyl 7-benzamido-3-methyl-3-cephem-4-carboxylate 1-oxide were obtained.

1. customthe precipitated N,N'-dicyclohexyl urea was removed by filtration
2. washthe precipitate washed with methylene chloride
3. washThe combined filtrates were washed sequentially with 2 N hydrochloric acid, saturated sodium bicarbonate solution (three times) and with water (twice)
4. customMethylene chloride was removed by evaporation in vacuo and toluene
5. additionwas added to the residue
6. customThe crystalline solid was isolated by filtration
7. washwashed with toluene
8. customUpon crystallization from a methylene chloride/toluene mixture