Copper(i)-free syntheses of [11C/18F]trifluoromethyl ketones from alkyl or aryl esters and [11C/18F]fluoroform

Abstract

Herein, we report a copper(I)-free method for labeling the trifluoroacetyl group with positron-emitting carbon-11 (t_1/2 = 20.4 min) or fluorine-18 (t_1/2 = 109.8 min) as part of our exploration of radiolabeled fluoroforms to access new radiolabeled chemotypes of interest for tracer development. Treatment of alkyl esters and aryl esters, containing electron-donating or electron-withdrawing groups, with [¹¹C/¹⁸F]fluoroform in the presence of strong base, gave [¹¹C/¹⁸F]trifluoromethyl ketones as novel radiolabeling synthons in moderate to high yields within 15 minutes.