Synthesis and characterization of well-defined l-lactic acid-caprolactone co-oligomers and their rhenium (I) and technetium(I) conjugates

Staring from l-lactide and ε-caprolactone, the corresponding lactic-caprolactone cooligomer with hydroxyl and carboxylic acid groups were synthesized. These oligomers were connected with chelating groups through a long chain tether, ready for transition metal binding. Coordination of organometallic rhenium(I) and technetium(I) complexes generated the conjugates in high yield and short time, satisfying the requirements for short-lived radiopharmaceuticals in clinical applications. A reasonable pharmacophore model has been established to guide the design of well-defined lactic acid oligomer for nuclear medicine.