(S)-(2-(2'-Pyridyl)ethyl)cysteamine and(S)-(2-(2'-Pyridyl)ethyl)-D,L-homocysteine as Ligands for the 'feo[M(CO)_3]~+'(M=Re,~(99m)Tc)Core

摘要

The reaction of fac-[NEt_4]_2[Re(CO)_3Br_3] with(S)-(2-(2'-pyridyl)ethyl)-cysteamine,LI,in methanol leads to the formation of the cationic fac-[Re(CO)_3(NSN)][Br] complex,1,with coordination of the nitrogen of the pyridine,the sulfur of the thioether,and the nitrogen of the primary amine.When fac-[NEt_4]_2[Re(CO)_3Br_3] reacts with the homocysteine derivative(S)-(2-(2'-pyridyl)ethyl)-D,L-homocysteine,L_2,the neutral fac-Re(CO)_3(NSO)complex,2,is produced with coordination of the nitrogen of the primary amine,the sulfur of the thioether,and the oxygen of the carboxylate group,while the pyridine ring remains uncoordinated.The analogous technetium-99m complexes,1' and 2',were also prepared quantitatively by the reaction of L_1 and L_2 with the fac-[~(99m)Tc(CO)_3(H_2O)_3]~+ precursor at 70 deg C in water.Given that both(S)-(2-(2'-pyridyl)ethyl)cysteamine and homocysteine can be easily N-or S-derivatized by a bioactive molecule of interest,both the NSN or NSO ligand systems could be used to develop target-specific radiopharmaceuticals for diagnosis and therapy.