Carbohydrate conjugates for molecular imaging and radiotherapy:: 99mTc(I) and 186Re(I) tricarbonyl complexes of N-(2′-hydroxybenzyl)-2-amino-2-deoxy-D-glucose

An approach to a new class of potential radiopharmaceuticals is demonstrated by the labeling of a glucosamine derivative with the tricarbonyls of Tc-99m and Re-186. The proligand HL2 (N-(2'-hydroxybenzyl)-2-amino-2-deoxy-d-glucose) was produced by hydrogenation of the corresponding Schiff base and reacted with [NEt4](2)[Re(CO)(3)Br-3] to form the neutral complex [(L-2)Re(CO)(3)] in 40% yield. H-1 and C-13 NMR spectra indicate that the {Re(CO)(3)} core is bound in a tridentate fashion via the amino N, phenolato O, and C-3 hydroxyl O atoms of the ligand. At the tracer-level, labeling of HL2 with [Tc-99m(CO)(3)(H2O)(3)](+) and [Re-186(CO)(3)(H2O)(3)](+) was achieved in aqueous conditions in 95 +/- 2% and 94 +/- 3% average radiochemical yields, respectively.