A compound according to formula Wherein R 1 is OH; R 2 is according to formula wherein R 7 is selected from the group consisting of C 1-6 -alkyl, C 6-14 -aryl-C 1-6 -alkyl, C 3-6 -alkylcarbonyl, C 6-14 -arylcarbonyl, C 1-6 -alkyl-C 6-14 -arylcarbonyl, C 6-14 -arylsulfonyl, C 1-6 -alkyl-C 6-14 -arylsulfonyl, C 6-14 -aryl-C 1-6 -alkylcarbonyl, C 6-14 -aryl-O-C 1-6 -alkylcarbonyl, C 6-14 -aryl-C 1-6 -alkyl-O-C 1-6 -alkyl-carbonyl, HOOC-(CH 2) m - - with m being from 0 to 6, a substituent of formula (V.1) with Ar being C 6-14 -aryl and n, p and q being independently from 0 to 6, C 6-14 -aryl-C 1-6 -alkyl-O-CO-NH-C 1-6 -alkyl-CO-, and C 6-14 -arylsulfonyl, and C 1-6 -alkyl-C 6-14 -arylsulfonyl, whereby alkyl and/or aryl in R 7 is optionally substituted by 1 to 6 halogen and/or CN; and R 8 is selected from the group consisting of C 6-14 -arylcarbonyl optionally substituted with 1 to 5 groups selected from halogen atoms, C 1-3 -alkyl sulfonyl groups, C 1-3 -alkyl groups and/or C 1-3 -alkoxy groups; C 3-6 -alkylcarbonyl; HOOC-(CH 2) m - - with m being from 0 to 6, a substituent of formula (V.1) as depicted hereinbefore with Ar being C 6-14 -aryl and n, p and q being independently from 0 to 6; and heteroarylcarbonyl having a 5- to 10-membered ring containing 1, 2 or 3 heteroatoms selected from the group consisting of O, N and S, the ring of the heteroarylcarbonyl optionally being substituted by 1 to 3 substituents selected from the group consisting of C 1-4 -alkyl, C 1-4 -alkoxy, C 2-4 -alkenyl, C 2-4 -alkenoxy, halogen and CN, whereby alkyl and/or aryl in R 8 is optionally substituted by 1 to 6 halogen and/or CN; R 3 is H; and R 4 and R 5 are independently selected from H and C 1-6 -alkylcarbonyl, whereby alkyl is optionally substituted by 1 to 6 halogen and/or CN, or R 4 and R 5 together form a single carbonyl group which forms a cyclic carbonate with both oxygen atoms it is bonded to; and or a pharmaceutically acceptable ester, amide, carbamate, solvate or salt thereof, including a salt of such an ester, amide or carbamate, and a solvate of such an ester, amide, carbamate or salt. R 1 is OH; R 2 is according to formula with Ar being C 6-14 -aryl and n, p and q being independently from 0 to 6, C 6-14 -aryl-C 1-6 -alkyl-O-CO-NH-C 1-6 -alkyl-CO-, and C 6-14 -arylsulfonyl, and C 1-6 -alkyl-C 6-14 -arylsulfonyl, whereby alkyl and/or aryl in R 7 is optionally substituted by 1 to 6 halogen and/or CN; and R 8 is selected from the group consisting of C 6-14 -arylcarbonyl optionally substituted with 1 to 5 groups selected from halogen atoms, C 1-3 -alkyl sulfonyl groups, C 1-3 -alkyl groups and/or C 1-3 -alkoxy groups; C 3-6 -alkylcarbonyl; HOOC-(CH 2) m - - with m being from 0 to 6, a substituent of formula (V.1) as depicted hereinbefore with Ar being C 6-14 -aryl and n, p and q being independently from 0 to 6; and heteroarylcarbonyl having a 5- to 10-membered ring containing 1, 2 or 3 heteroatoms selected from the group consisting of O, N and S, the ring of the heteroarylcarbonyl optionally being substituted by 1 to 3 substituents selected from the group consisting of C 1-4 -alkyl, C 1-4 -alkoxy, C 2-4 -alkenyl, C 2-4 -alkenoxy, halogen and CN, R 3 is H; and R 4 and R 5 are independently selected from H and C 1-6 -alkylcarbonyl, whereby alkyl is optionally substituted by 1 to 6 halogen and/or CN, or R 4 and R 5 together form a single carbonyl group which forms a cyclic carbonate with both oxygen atoms it is bonded to; and