[¹⁸F]Fluoropropylsulfonyl chloride: A new reagent for radiolabeling primary and secondary amines for PET imaging

In vivo molecular imaging with positron emission tomography (PET) requires the preparation of an appropriate positron-emitting radiotracer. New methods for the introduction of F-18 into biologically interesting molecules could increase the availability of specific PET radiotracers and increase the application of PET to the study of human diseases. In this work, [¹⁸F] fluoropropylsulfonyl chloride was synthesized from 3-toluenesulfonyloxypropyl thiocyanate in two steps and was successfully incorporated into molecules containing a reactive amino group. Both a primary amine, L-phenylalanine ethyl ester hydrochloride, and a secondary amine, 1-(2-methoxyphenyl)-piperazine, were successfully radiolabeled by this method. The entire radiochemical synthesis required 90 min. The products were obtained in 25.7 ± 2.3% (n = 3) and 22.8 ± 9.1% (n = 6) (EOB). This method provides a useful and easy way to make new F-18 labeled radiopharmaceuticals for PET imaging.