Synthesis and in vitro evaluation of 18F-labelled S-fluoroalkyl diarylguanidines: Novel high-affinity NMDA receptor antagonists for imaging with PET

Abstract Two S -[ 18 F]fluoroalkylated diarylguanidines were synthesized and evaluated in vitro as potential tracers for imaging of N -methyl- d -aspartate receptors (NMDARs) with positron emission tomography (PET). [ 18 F] 1 and [ 18 F] 10 were synthesized by [ 18 F]fluoroethylation and [ 18 F]fluoromethylation of the thiol precursor 6 , respectively. [ 18 F] 1 is a promising candidate NMDAR PET tracer, with low nanomolar affinity for the NMDA PCP-site, high selectivity and moderate lipophilicity.