Novel coumarin derivatives and the salts thereof, a process for the preparation thereof and their use in the pharmaceutical field

Coumarin derivatives of formula (I):

• 6
• wherein:
• X═O or S;
• n=zero, 1, 2, 3 or 4;
• R5 and R6, which can be the same or different, are optionally unsaturated C1-C4 alkyl groups, or together with the nitrogen atom they form a residue of cyclic amines optionally containing other heteroatoms;
• R1═CH3 or phenyl;
• R2 and R4, which can be the same or different, are H, OH, allyl, halogen or methyl;
• R3═H, straight or branched, saturated or unsaturated C1-C10 alkyl, which can bear OH groups, amido groups, residues of simple or derivatized sugars, or residues of optionally derivatized amino acids, or can be an optionally branched alkylene chain, (“spacer”), which links together the two residues, which can be the same or different, of formula (II)
• 7
• wherein X, n, R1, R2, R4, R5 and R6 have the meanings defined above.