Pyrrolidine derivatives of the formula ##STR1## wherein R.sup.1 is hydrogen or lower alkanoyl, R.sup.2 is hydrogen or lower alkyl and R.sup.3 is hydrogen, lower alkyl or a group of the formula --(CH.sub.2).sub.n --NR.sup.4 R.sup.5, wherein n is a whole number of 2 to 4 and R.sup.4 and R.sup.5 each, independently, are hydrogen or lower alkyl, or R.sup.4 and R.sup.5 taken together with the nitrogen atom are a pyrrolidinyl, piperidinyl, piperazinyl or morpholinyl group which is optionally substituted by one or two lower alkyl groups, enantiomers thereof, and acid addition salts of compounds of formula I and their enantiomers which are basic, are useful in the control or prevention of cerebral insufficiency or in the improvement of intellectual capacity. The compounds of formula I of the invention can be prepared starting from starting materials hereinafter described, and are useful as medicaments, for example, in the form of pharmaceutical preparations.
2-(2-Oxo-1-pyrrolidinyl)acetic acids of the formula ##STR1## wherein R.sup.2 is hydrogen or lower alkyl and R.sup.11 is hydrogen, lower alkanoyl or another group readily cleavable by means of ammonia, are described. The compounds of formula III of the invention are useful to prepare the compound of formula I of the invention which are useful as medicaments, for example, in the form of pharmaceutical preparations.