Abstract
Abstract[18F]2‐Fluoroethyl tosylate ([18F]FEOX, X=Ts) is widely used for labeling radiotracers for positron emission tomography (PET). Little work has been reported on syntheses of other [18F]2‐fluoroethyl arylsulfonates ([18F]FEOX) that bear a less electron‐rich aryl group, even though these might offer enhanced reactivities. Thus, a series of novel [18F]FEOX (X=benzenesulfonyl, brosyl, nosyl, 3,4‐dibromobenzenesulfonyl) were synthesized and reactivities compared to [18F]FEOTs. Precursors for radiolabeling (bis‐ethylene glycol arylsulfonates) and reference FEOX were synthesized (alcohol+arylsulfonyl chloride+KOSiMe3 in THF). Regardless of substitution pattern, [18F]FEOX (110°C, 5 min, acetonitrile) were obtained in similar decay‐corrected isolated radiochemical yields (RCY; 47–53%). All [18F]FEOX gave excellent RCYs (64–87%) of the dopamine uptake radioligand, [18F]FECNT (130°C, 10 min, acetonitrile). The 3,4‐dibromobenzensulfonate gave the highest RCY of [18F]FECNT (87%) and this HPLC‐purified labeling agent was used directly for efficient [18F]FECNT production. When the secondary aniline of an amyloid probe (HM‐IMPY) or p‐nitrophenol was reacted with [18F]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 [18F]FEOX and their ease of syntheses via stable precursors, such agents (particularly 3,4‐dibromobenzenesulfonate) should be considered as alternatives to [18F]FEOTs. Copyright © 2005 John Wiley & Sons, Ltd.
Published Version
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