Beyond azide-alkyne click reaction: easy access to 18F-labelled compounds via nitrile oxide cycloadditions

Radiofluorinated 4-fluorobenzonitrile oxide and N-hydroxy-4-fluorobenzimidoyl chloride rapidly react with different alkenes and alkynes under mild conditions. These cycloadditions are suitable for the preparation of low-molecular weight radiopharmaceuticals and, in a strain-promoted variant, can enable easy labelling of sensitive biopolymers