Radiosyntheses and reactivities of novel [ 18 F]2‐fluoroethyl arylsulfonates

[ 18 F]2‐Fluoroethyl tosylate ([ 18 F]FEOX, X=Ts) is widely used for labeling radiotracers for positron emission tomography (PET). Little work has been reported on syntheses of other [ 18 F]2‐fluoroethyl arylsulfonates ([ 18 F]FEOX) that bear a less electron‐rich aryl group, even though these might offer enhanced reactivities. Thus, a series of novel [ 18 F]FEOX (X=benzenesulfonyl, brosyl, nosyl, 3,4‐dibromobenzenesulfonyl) were synthesized and reactivities compared to [ 18 F]FEOTs. Precursors for radiolabeling ( bis ‐ethylene glycol arylsulfonates) and reference FEOX were synthesized (alcohol+arylsulfonyl chloride+KOSiMe 3 in THF). Regardless of substitution pattern, [ 18 F]FEOX (110°C, 5 min, acetonitrile) were obtained in similar decay‐corrected isolated radiochemical yields (RCY; 47–53%). All [ 18 F]FEOX gave excellent RCYs (64–87%) of the dopamine uptake radioligand, [ 18 F]FECNT (130°C, 10 min, acetonitrile). The 3,4‐dibromobenzensulfonate gave the highest RCY of [ 18 F]FECNT (87%) and this HPLC‐purified labeling agent was used directly for efficient [ 18 F]FECNT production. When the secondary aniline of an amyloid probe (HM‐IMPY) or p ‐nitrophenol was reacted with [ 18 F]FEOX, RCYs were appreciably higher for brosylate and nosylate than for tosylate, while 3,4‐dibromobenzenesulfonate again gave the highest RCY. Owing to the high reactivity of the new [ 18 F]FEOX and their ease of syntheses via stable precursors, such agents (particularly 3,4‐dibromobenzenesulfonate) should be considered as alternatives to [ 18 F]FEOTs. Copyright © 2005 John Wiley & Sons, Ltd.