18F‐FESB: synthesis and automated radiofluorination of a novel 18F‐labeled pet tracer for β‐amyloid plaques

1‐(2′‐[¹⁸F]‐fluoroethoxy)‐2,5‐bis(4′‐methoxystyryl)benzene (¹⁸F‐FESB) was synthesized in ～76% radiochemical yield (specific activity >58.6 GBq or 1.58 Ci/µmol) in an Advanced Cyclotron Systems' automated synthesis unit by nucleophilic substitution of 1‐(2′‐toluenesulfonylethoxy)‐2,5‐bis(4′‐methoxystyryl)benzene and purified using reversed phase column chromatography. When performed in the presence of ionic fluid, either 1‐butyl‐3‐methylimidazolium tetrafluoroborate (Bmimtetrafluoroborate; BmimBF₄) or 1‐ethyl‐3‐methylimidazolium trifluoromethanesulfonate (Emimtriflate; EmimTFMS), radiochemical yields of ¹⁸F‐FESB ranged from 17 to 76%. The radiochemical yields were consistently lower (～3–7%) in the absence of these ionic fluids. Copyright © 2005 John Wiley & Sons, Ltd.