Reaction of diiodomethane (I) with [18F]fluoride at 100 C leads to the radiolabeled fluoromethyl iodide (II). The known peripheral benzodiazepine receptor ligand (III) is then alkylated with iodide (II) in the presence of NaH in DMF to furnish the title compound.

Reaction of 2-bromoethyl triflate (I) with [18F]fluoride in boiling o-dichlorobenzene leads to the radiolabeled 1-bromo-2-fluoroethane (II). The known peripheral benzodiazepine receptor ligand (III) is then alkylated with bromide (II) in the presence of NaH in hot DMF to furnish the title compound.