Synthesis and Derivatization of 1,1-[18 F]Difluorinated Alkenes.

A general method for the synthesis of 1,1-[18 F]difluorinated alkenes from [18 F]fluoride is reported. This transformation is highly regioselective giving the desired 18 F-fluoroalkenes with radiochemical purities of up to 77 % within 20 minutes and a molar activity (Am ) of 1 GBq μmol-1 . The transformations are operationally simple to perform and were readily translated onto a commercial automated synthesis unit. The resultant 1,1-[18 F]difluorinated alkene motif is prevalent in numerous drug molecules, and this is the first general method to synthesize this motif with fluorine-18. 18 F-fluorinated alkenes are excellent building blocks and participate in a number of post-labeling transformations to access a range of 18 F-perfluorinated functional groups that have never before been radiolabeled with non-carrier-added [18 F]fluoride. This method considerably expands the range of 18 F-motifs accessible to radiochemists.