| 摘要 |
A process for the preparation of 6-carbalkoxy-8-ethyl-5-oxo-2-piperazinyl-5,8-dihydro pyrido ¢2,3-d! pyrimidine (II) and salts thereof comprising reacting a 6-carbalkoxy-8-ethyl-2-halogeno-5-oxo-5,8-dihydro pyrido ¢2,3-d! pyrimidine with a neutral salt of piperazine in a dilute alcoholic medium in the presence of a base for maintaining the pH between 2.7 and 3.6. The compounds (II) are obtained as their salts and may be liberated by alkaline treatment. The esters of formula (II) may be hydrolyzed to give the corresponding acids, which are antibacterial products particularly active on Gram-negative germs. |
