Compound of formula: and pharmaceutically acceptable salts thereof, wherein X and Y are different one from the other and are O or NH; R 1 is selected from the group consisting of C 1 -C 6 -alkyl; C 3 -C 6 -cycloalkyl and halo C 1 -C 3 -alkyl. R 2 is selected from the group consisting of: - C 1 -C 8 alkyl; - C 3 -C 6 cycloalkyl; - phenyl unsubstituted or substituted with at least one group selected from a -O-C 1 -C 4 -akyl and C 1 -C 4 -alkyl; - benzothiophene; - a 5 or 6 membered-heteroaromatic ring selected from pyridine and pyrrole. R 3 is selected from the group consisting of: - C 1 -C 8 alkyl; - (CH 2) m COCH 3, wherein m is an integer comprised between 1 and 4; - (CH 2) n -Z, wherein n is an integer comprised between 1 and 3and Z is selected from the group consisting of dialkylamine, C 3 -C 6 -cycloalkyl, benzotriazole, isoindol-1,3 -dione-2-yl, imidazole, triazole, indole, furane, and phenyl, the latter being unsubstituted or substituted with one or more groups selected from halo, C 1 -C 3 alkyl, O-C 1 -C 3 alkyl and C 1 -C 3 alkylamino; - C 3 -C 6 cycloalkyl unsubstituted or substituted with one or more groups selected from halo, and C 1 -C 3 alkyl; - 2-methyl-1,3-oxazol-4-yl; - phenyl unsubstituted or substituted with one or more groups selected from C 1 -C 3 alkyl, hydroxyl, halo and nitro for use as a medicament. and pharmaceutically acceptable salts thereof, wherein X and Y are different one from the other and are O or NH; R 1 is selected from the group consisting of C 1 -C 6 -alkyl; C 3 -C 6 -cycloalkyl and halo C 1 -C 3 -alkyl. R 2 is selected from the group consisting of: - C 1 -C 8 alkyl; - C 3 -C 6 cycloalkyl; - phenyl unsubstituted or substituted with at least one group selected from a -O-C 1 -C 4 -akyl and C 1 -C 4 -alkyl; - benzothiophene; - a 5 or 6 membered-heteroaromatic ring selected from pyridine and pyrrole. - C 1 -C 8 alkyl; - C 3 -C 6 cycloalkyl; - phenyl unsubstituted or substituted with at least one group selected from a -O-C 1 -C 4 -akyl and C 1 -C 4 -alkyl; - benzothiophene; - a 5 or 6 membered-heteroaromatic ring selected from pyridine and pyrrole. R 3 is selected from the group consisting of: - C 1 -C 8 alkyl; - (CH 2) m COCH 3, wherein m is an integer comprised between 1 and 4; - (CH 2) n -Z, wherein n is an integer comprised between 1 and 3and Z is selected from the group consisting of dialkylamine, C 3 -C 6 -cycloalkyl, benzotriazole, isoindol-1,3 -dione-2-yl, imidazole, triazole, indole, furane, and phenyl, the latter being unsubstituted or substituted with one or more groups selected from halo, C 1 -C 3 alkyl, O-C 1 -C 3 alkyl and C 1 -C 3 alkylamino; - C 3 -C 6 cycloalkyl unsubstituted or substituted with one or more groups selected from halo, and C 1 -C 3 alkyl; - 2-methyl-1,3-oxazol-4-yl; - phenyl unsubstituted or substituted with one or more groups selected from C 1 -C 3 alkyl, hydroxyl, halo and nitro for use as a medicament. - C 1 -C 8 alkyl; - (CH 2) m COCH 3, wherein m is an integer comprised between 1 and 4; - (CH 2) n -Z, wherein n is an integer comprised between 1 and 3and Z is selected from the group consisting of dialkylamine, C 3 -C 6 -cycloalkyl, benzotriazole, isoindol-1,3 -dione-2-yl, imidazole, triazole, indole, furane, and phenyl, the latter being unsubstituted or substituted with one or more groups selected from halo, C 1 -C 3 alkyl, O-C 1 -C 3 alkyl and C 1 -C 3 alkylamino; - C 3 -C 6 cycloalkyl unsubstituted or substituted with one or more groups selected from halo, and C 1 -C 3 alkyl; - 2-methyl-1,3-oxazol-4-yl; - phenyl unsubstituted or substituted with one or more groups selected from C 1 -C 3 alkyl, hydroxyl, halo and nitro for use as a medicament.