Patent ID: 6838561

Claim:
A compound of formula (1): wherein R 1 is selected from the gronp consisting of a hydrogen atom, C 1 to C 5 alkyl, C 1 to C 5 mono or dihydroxyalkyl, phenyl or benzyl optionally substituted with a hydroxyl, amino or C 1 to C 5 alkoxy group; and R 2 is selected from the group consisting of C 1 to C 5 alkyl, C 1 to C 5 mono or dihydroxyalkyl, phenil or benzyl optionally substituted with a hydroxyl, amino or C 1 to C 3 alkoxy group; or R 1 and R 2 together with the nitrogen atom to which they are attached form a C 5 to C 6 saturated or unsaturated ring optionally containing in the ring one or more additional hetero atoms selected from O, S and N atoms.