Synthesis of 18 F-labelled aryl trifluoromethyl ketones with improved molar activity.

A method for the radiosynthesis of 18 F-labelled aryl trifluoromethyl ketones starting from widely available Weinreb amides using [ 18 F]fluoroform is presented. The method uses potassium hexamethyldisilazane as base and delivers products in high molar activity (up to 24 GBq μmol -1 ) and excellent radiochemical conversions. The applicability for PET tracer synthesis is demonstrated by the radiosynthesis of ten (hetero)aryl trifluoromethylketones, bearing electron-withdrawing and -donating substituents including a derivative of bioactive probenecid.