| 摘要 |
There is provided a process for preparing in high yields a 6-[D(-)- alpha-(4-C1-C4-alkyl-2,3-dioxo-1- piperazinocarbonylamino)- phenylacetamido]penicillanic acid, or pharmaceutically acceptable salt thereof, in which a 4-C1-C4-alkyl- 2,3-dioxo-1-piperazinocarbonyl halide is added under controlled pH conditions to a solution or suspension of ampicillin in a mixture of ethyl acetate and water in the presence of a base to form a reaction mixture, the resulting mixture is agitated until the reaction is completed, the reaction mixture is acidified, and the desired antibiotic is recovered as a crystalline product under controlled pH conditions and using controlled amounts of ethyl acetate as solvent. |
