Synthesis of 18 F‐labelled stilbenes from 4‐[ 18 F]fluorobenz‐aldehyde using the Horner–Wadsworth–Emmons reaction

The first application of the Horner–Wadsworth–Emmons reaction in 18 F‐chemistry is described. This carbonyl‐olefination reaction was performed via a ‘multi‐step/one‐pot’ reaction by the coupling of benzylic phosphonic acid esters (3,5‐bis‐methoxymethoxybenzyl)‐phosphonic acid diethyl ester 2e , (4‐methoxy‐methoxybenzyl)‐phosphonic acid diethyl ester 3e and (4‐dimethyl‐aminobenzyl)phosphonic acid diethyl ester 4d ) with 4‐[ 18 F]fluorobenzaldehyde to give the corresponding 18 F‐labelled stilbenes [ 18 F]2g , [ 18 F]3g and [ 18 F]4e exclusively as the expected E ‐isomers. The radiochemical yields ranged from 9% to 22% (based upon [ 18 F]fluoride, including HPLC purification). The specific activity reached up to 90 GBq/µmol. Copyright © 2007 John Wiley & Sons, Ltd.