[Study of the relationship between structure and anticonvulsant activities of 5-substituted-1-butry-3-pyrazolidinones and their synthesis].

According to the quantitative structure-activity relationship studies of 3-pyrazolidinones with different substituent on positions 1 and 5 reported previously, the anticonvulsant activity is parabolically related with the total fragment constent (Fr hydrophobic parameter) of the 1 and 5 substituents of 3-pyrazolidion. The optimum Fr was about 5.6. Therefore, eleven new 5-substituted-3-pyrazolidinones have been synthesized. Pharmacological test showed that they are all potent anticonvulsant agents. Among them 1-n-butyl-5-(p-chlorophenyl)-3-pyrazolidinone was shown to be the most potent so far synthesized.