Amnesia-reversal activity of a series of 5-alkoxy-1-arylcarbonyl-2-pyrrolidinones and 5-alkoxy-1-arylmethyl-2-pyrrolidinones

Abstract

A series of 5-alkoxy-1-arylcarbonyl-2-pyrrolidinones (1-27) were prepared by condensation of arylcarbonyl chlorides with 5-alkoxy-2 pyrrolidinones in the presence of butyl lithium in tetrahydrofuran. Alkylation of these intermediates with substituted benzyl bromides or chlorides, under solid/liquid phase-transfer conditions (KOH/Bu4NBr) in tetrahydrofuran, yielded 5-alkoxy-1-arylmethyl-2-pyrrolidinones (28-48). In the first series, the compounds with a 5-n-pentyloxy group had maximal ECS-induced amnesia reversing activity in mice, and in the second series, those with a 5-n-octyloxy group. In both series, substitutions on the phenyl ring had detrimental effects. The two most promising compounds 1-benzoyl-5-n-pentyloxy-2-pyrrolidinone (14) and 1-benzyl-5-n-octyloxy-2-pyrrolidinone (37) were more potent than piracetam and aniracetam and active over broader dose ranges: 50-200 and 50-400 mg/kg, po. Both compounds also reversed scopolamine-induced amnesia in mice, from 50 to 400 mg/kg, po (14) and from 100 to 400 mg/kg, po (37). Finally, 37 showed remarkable activity in protecting the mouse brain against chemically induced hypoxia, with a minimal effective dose of 50 mg/kg, ip, or 100 mg/kg, ip, in NaNO2- or KCN-induced hypoxia. © 1991.