Patent ID: 6872747

Claim:
A compound of a general formula (I) wherein R 1 is H; a linear or branched C 1-6 alkyl; C 1-6 alkyl which is mono -or polysubstituted by a C 6-14 aryl; linear or branched carboxy C 1-18 alkyl; linear or branched C 1-6 , alkoxycarbonyl; linear or branched C 1-12 alkylcarbonyl; C 2-6 alkenyl; C 2-6 alkinyl; linear or branched cyano C 1-6 alkyl; benzyloxy; 9-fluorenylmethoxycarbonyl (Fmoc); triphenylmethyl (Tr); 2-(4′-pyridyl)ethoxycarbonyl (Pyoc); or diphenylmethylsilyl (DPMS) residue, R 2 is H; a linear or branched C 1-6 alkyl; C 1-6 alkyl which is mono -or polysubstituted by C 6-14 aryl; linear or branched carboxy C 1-18 alkyl; linear or branched C 1-6 alkoxycarbonyl; linear or branched C 1-12 alkylcarbonyl; C 2-6 alkenyl; C 2-6 alkinyl; linear or branched cyano C 1-6 alkyl; benzyloxy; 9-fluorenylmethoxycarbonyl (Fmoc); triphenylmethyl (Tr); 2-(4′-pyridyl)ethoxycarbonyl (Pyoc); or diphenylmethylsilyl (DPMS) residue, X is O, S, a NOH or NOR 4 residue, wherein R 4 is a linear or branched C 1-6 alkyl; C 1-6 alkyl residue which is mono- or polysubstituted by C 6-14 aryl; linear or branched carboxy C 1-18 alkyl; linear or branched C 1-6 alkoxycarbonyl; or linear or branched C 1-12 alkylcarbonyl residue, Y is O or S and Z is H or OR 3 wherein R 3 is H, linear or branched C 1-6 alkyl; C 1-6 alkyl residue which is mono- or polysubstituted by C 6-14 aryl; linear or branched carboxy C 1-18 alkyl; linear or branched C 1-6 alkoxycarbonyl; linear or branched C 1-12 alkylcarbonyl; C 2-6 alkenyl; C 2-6 alkinyl; linear or branched cyano C 1-6 alkyl; benzyloxy; 9-fluorenyl-methoxycarbonyl (Fmoc); triphenylmethyl (Tr); 2-(4′-pyridyl) ethoxycarbonyl (Pyoc); or diphenylmethylsilyl (DPMS) residue.