Readily accessible heteroaromatic silanes as fluoride acceptors in a mild ^(18)F-^(19)F isotopic exchange

Silicon fluoride acceptors (SiFAs) are under study as new imaging agents useful for positron emission tomography (PET).[1] They are readily labeled with the radioisotope flourine-18 via a fast and mild ^(18)F–^(19)F isotopic exchange reaction (IEX).[2] The application of SiFA-based PET probes has been hampered by their high intrinsic lipophilicity, originating from bulky tert-butyl groups required for in vivo stabilization of the Si–^(18)F bond. Herein, we present the first example of ^(18)F–labeled N- and S-heteroaromatic SiFAs with improved lipophilicity. Furthermore, we demonstrate that simple cartridge-based purification is sufficient, which avoids the usual time-consuming HPLC step.