Ethyl Pinacol Boronates as Advantageous Precursors for Copper-Mediated Radiofluorination

(Hetero)aryl pinacol boronic esters are routinely used for ¹⁸F-labeling and have accelerated numerous diagnostic and drug discovery programs. An analysis of the current state-of-play, however, highlights a pending challenge. Reports have indicated that some pinacol boronic esters are unstable and difficult to purify, hindering broader adoption in the clinic. Herein, we demonstrate that more stable boronic esters derived from 3,4-diethylhexane-3,4-diol (Epin) are highly suitable for copper-mediated radiolabeling. Impact is illustrated with the automated synthesis of [¹⁸F]FMZ.