Radiosynthesis of (±)‐(2‐((4‐(2‐[¹⁸F]fluoro‐ethoxy)phenyl)bis(4‐methoxy‐phenyl)methoxy)ethylpiperidine‐3‐carboxylic acid: a potential GAT‐3 PET ligand to study GABAergic neuro‐transmission in vivo

2-[18F]Fluoroethyl tosylate – a versatile tool for building18F-based radiotracers for positron emission tomography

“…36,47,55,79,87,91,101 The reason is that the synthesis of the corresponding tosylated/mesylated precursors has failed 79,86 or afforded extremely low yields (2-3%). 92,102 Under these circumstances, [ 18 F]fluoroethylation is the sole method to provide the desired radiotracer. Whether [ 18 F]fluoroethylation may be performed either by direct labeling or by introduction of the radiolabeled precursor [ 18 F]FETs (indirect approach) is dependent on the chemical behavior and reactivity of a particular precursor compound.…”

“…In contrast, the [ 18 F]fluoroethylation with [ 18 F]FETs was performed as a one-pot method and the piperazine in DMSO was added to the labeling agent. By using this approach, the overall RCY could be enhanced to 23% but surprisingly, as a drawback, the specific activity dropped from 92 Vandetanib is an antiangiogenic TKI also showing a methylpiperidine moiety and served as a lead for the development of an N-[ 18 F]fluoroethylated radiotracer which was built from a piperidine-substituted quinazoline and [ 18 F]FETs (Fig. 46).…”

“…52). 92 In summary, the direct radiolabeling approach is less efficient. Additionally, it should be considered that the ethyl-tosylated precursor was difficult to synthesize with a yield of only 2.6%.…”

“…Fig. 52 Synthesis of an O-[ 18 F]fluoroethylated triphenyl-substituted piperidine-3-carboxylic acid 91,92. …”

Visualizing GABA transporters in vivo: an overview of reported radioligands and future directions

“…For GAT3, however, Schirrmacher et al . attempted to synthesize a radioligand which they based on GAT3 inhibitor ( S )-SNAP-5114 (S)-42 [ 75 ]. This inhibitor was developed by Dhar et al .…”