Heterocyclic compounds, their preparation and their use as medicaments, in particular as anti-alzheimer agents

A compound of formula G

• or a pharmaceutical salt or a stereoisomer of G;
• wherein:
• the dotted circle line represents one double bond between CR5-CR6, and another double bond between either CR2-CR3 or CR3-CR4;
• and
• a) except as provided in c) below, R1, R2, R3, and R4, which may be identical or different, are each selected from the group consisting of hydrogen, OH, (C1-C8) alkyl, aryl, heteroaryl, (C1-C8) alkylaryl, aryl (C1-C8) alkyl, alkoxy, hydroxy (C1-C8) alkyl, alkoxy (C1-C8) alkyl, phenyl, (CH2)n—COOH, Z and Z1, and
• b) R5 and R6 taken together with the carbon atoms to which R5 and R6 are attached form a ring selected from the group consisting of a 6-membered aromatic ring and a 5- or 6-membered heterocyclic ring, the ring being optionally substituted by one or more group, identical or different, each selected from the group consisting of OH, (C1-C8) alkyl, aryl, heteroaryl, (C1-C8) alkylaryl, aryl (C1-C8) alkyl, alkoxy, hydroxy (C1-C8) alkyl, alkoxy (C1-C8) alkyl, phenyl, (CH2)n—COOH, Z and, Z1;
• and
• c) at least one group among R2 and R3 is an electron withdrawing group selected from the group consisting of COOR, COSR, CONRR′, CN, COR, CF3, SOR, SO2R, SONRR′, SO2NRR′, NO2, halogen and heteroaryl, wherein
• R, and R′ are each a group selected from the group consisting of H, alkyl, cycloalkyl, arylalkyl, heteroarylalkyl, hydroxyalkyl, alkoxyalkyl, aryloxyalkyl, alkylaminoalkyl, aminoalkyl, heteroaryloxyalkyl, halogenoalkyl, thioalkyl, thioalkoxyalkyl, aryl, alkylaryl, hydroxyaryl, alkoxyaryl, aryloxyaryl, aminoaryl, alkylaminoaryl, halogenoaryl, heteroaryl, alkylheteroaryl, alkoxyheteroaryl, aminoheteroaryl, alkylaminoheteroaryl and halogenoheteroaryl, or
• R and R′ taken together with the nitrogen atom to which they are attached form an heterocyclic ring of at least 3 members optionally substituted by one or more groups being as defined for R2, or
• R and R′ taken together with the nitrogen atom to which they are attached form a fused polyheterocyclic system, optionally tetrahydroisoquinoline, indoline or isoindoline, optionally substituted by one or more group being as defined for R2;
• and wherein
• Z is a group defined by formula -(L)m-Z1, wherein L is selected from the group consisting of (C1-C8) alkyl, aryl, heteroaryl, phenyl, (C1-C8) alkylaryl and aryl(C1-C8) alkyl;
• Z1 is defined by formula
• wherein X and Y are each selected from the group consisting of O and S;
• wherein R7 and R8, which may be identical or different, are each selected from the group consisting of hydrogen, (C1-C8) alkyl, aryl, heteroaryl, (C1-C8) alkylaryl, phenyl, cyclopropyl and(CH2)n—COOH;
• and
• wherein n and m are each an integer ≧1, optionally m is comprised between 1 and 4 and n is comprised between 1 and 6;
• and provided that at least one of R1, R2, R3 and R4 is Z or Z1 and that R1 is not H or Z1.