Hydrogenation over Raney nickel of the methyl ester of 1H-pyrazoline-3-carboxylic acid and also of its 4-phenyl and 5-methoxycarbonyl-substituted analogs, leads respectively to 3- aminopyrrolidin-2-one, its 4-phenyl-and 5-methoxycarbonyl derivatives, predominantly to the trans isomer. Under the same conditions 1-amino-4-methoxycarbonylpyrrolidin-2-one was obtained from 3, 4-di (methoxycarbonyl)-1H-pyrazoline, but 3, 4, 5-tri ( ...
