The labelling of 2‐oxoquazepam with electrophilic ¹⁸F

Abstract

Abstract 2‐Oxoquazepam, 7‐chloro‐1‐(2,2,2‐trifluoroethyl)‐1,3‐dihydro‐5‐(2‐fluorophenyl)‐2H‐1,4‐benzo‐diazepine‐2‐one, is a benzodiazepine agonist. It has been shown to bind in vitro with a higher affinity to benzodiazepine type 1 receptors than to type 2 receptors. Here we report the synthesis of a trimethyltin precursor and demonstrate the feasibility of using it for radiolabelling acid‐ and base‐sensitive benzodiazepine structures such as 2‐oxoquzepam. Conversions of the electrophilic fluorine to [ 18 F]‐2‐oxoquazepam on the order 20–25% were obtained.