A process for the preparation of a C(3)-C(4)-transconfigurated.gamma.-butyrolactam of the formula (I) ##STR1## in which R.sup.1 represents hydrogen or alkyl, aryl or aralkyl with in each case up to 10 carbon atoms andR.sup.2 and R.sup.3 are identical or different and represent hydrogen, alkyl, aryl, aralkyl, alkoxy, aryloxy or aralkoxy with in each case up to 10 carbon atoms, acyl with up to 18 carbon atoms, trifluoromethyl, trifluoromethoxy, nitro, hydroxyl, halogen, amino, carboxyl, sulpho, dialkylamino with up to 4 carbon atoms in the alkyl groups or acylamino with up to 18 carbon atoms, in the form of their isomers, isomer mixtures, racemates or optical antipodes, comprising oxidizing a compound of the formula (II) ##STR2## in which R.sup.1, R.sup.2 and R.sup.3 have the above-mentioned meanings, in an inert organic solvent in the presence of a base. Such .gamma.-butyrolactams have an antiamnesic action.