A one-step automated high-radiochemical-yield synthesis of 18F-FECNT from mesylate precursor

Abstract

2 β-Carbomethoxy-3 β-(4-chlorophenyl)-8-(2-[ 18F]fluoroethyl)nortropane ( 18F-FECNT) is a potential dopamine transporter imaging agent. In this article, a new mesylate precursor was prepared and a one-step automated synthesis of 18F-FECNT was developed. The mesylate precursor ( 4) was synthesized from 2 β-carbomethoxy-3 β-(4-chlorophenyl)tropane ( 1) by N-demethylation, hydroxyethylation followed by mesylation at a total yield of 47%. [ 18F]fluorination was performed by heating 4 mg mesylate precursor and K[ 18F] in 1 ml acetonitrile at 90 °C for 20 min. The crude 18F-FECNT was obtained with a radiolabeling yield of 48%. After purification by preparative high performance liquid chromatography (HPLC), the final 18F-FECNT product was obtained with a radiochemical purity of 98.4% and a decay corrected radiochemical yield of 33±9% (and the uncorrected radiochemical yield was 19±5%, n=5). The duration of the total procedure was 80–90 min.