Compounds with nootropic action, their preparation, pharmaceutical compositions containing them, and use thereof

A process for the preparation of compounds of the general formula (I)

• wherein:
• A is selected from the group consisting of carbocyclic aromatic groups, heterocyclic aromatic groups, and arylC1-4alkyl;
• R1 is selected from the group consisting of:
• hydrogen,
• arylC1-7alkyl, optionally substituted on the aryl moiety with one or more groups chosen among hydroxy, C1-4alkoxy, halogen, haloC1-4alkyl;
• heterocyclylC1-7alkyl, optionally substituted on the heterocyclyl moiety with one or more groups chosen among C1-4alkyl and hydroxy;
• and
• C1-7 alkyl, optionally interrupted by an oxygen or sulphur atom or optionally substituted at any position by one or more groups chosen among hydroxy, thio, amino, carboxyl, aminocarbonyl, guanidinyl;
• R2 is selected from the group consisting of hydrogen, C1-4alkyl, arylC1-4alkyl and phenyl;
• or else R1 and R2, taken together, form a saturated carbocyclic ring containing from 3 to 8 carbon atoms;
• R3 is selected from the group consisting of hydrogen, C1-4alkyl, arylC1-4alkyl, CONH2 and COOR5 in which R5 is selected from the group consisting of hydrogen and C1-4alkyl;
• R4 is selected from the group consisting of hydrogen, C1-4alkyl, aryl, arylC1-4alkyl and heterocyclyl;
• n is 2, 3 or 4;
• in the form of a racemic mixture or in the form of enantiomers, and pharmaceutically acceptable salts thereof, comprising the following stages:
• i) reacting an aminoacid of formula (IV) or of one of its activated derivatives
• with a compound of formula (V)
• A-NH2 (V)
• to obtain a compound of formula (VI):
• in which R1, R2 and A are as defined above, and P is H or a suitable protective group;
• ii) reacting the compound of formula (VI) obtained in stage i) with a compound of formula (VII)
• to obtain a compound of formula (VIII)
• in which A, R1, R2, R3, R4 and n are as defined above, P is defined as above, and R′ is an alkyl group;
• iii) optionally removing the protective group P by means of hydrogenolysis of the compound of formula (VIII) obtained from stage ii), to obtain the corresponding compound (VIII), in which P is H;
• and
• iv) cyclizing of the compound of formula (VIII), in which P is H coming from stage ii) or from stage iii), to obtain the desired compound of formula (I).