Nucleophilic ring-opening of activated aziridines: A one-step method for labeling biomolecules with fluorine-18

The direct labeling of biomolecules with fluorine-18 is highly desirable. An option is the ring-opening of an activated aziridine moiety in a biomolecule using 18F-fluoride. Therefore, a series of aziridine-based model compounds and three aziridine-based biomolecules four aziridine-based model compounds were synthesized and evaluated as potential precursors for a direct one-step radiolabeling with fluorine-18. High to moderate yields of 18F-incorporation were achieved under mild labeling conditions. The influence of different activating groups, reaction temperature, solvent and base was investigated. The applicability of this method for the direct 18F-radiolabeling of biomolecules for positron emission tomography (PET) studies is illustrated with examples.