Session 8: Radiopharmaceutical Chemistry-Halogens II

• Publisher: John Wiley and Sons
• Year: 2003
• Tongue: French
• Weight: 639 KB
• Volume: 46
• Category: Article
• ISSN: 0022-2135
• DOI: 10.1002/jlcr.757

✦ Synopsis

Recently, there is much interest to label choline with C-11 and F-18 for PET imaging of various tumors. Hara et al. reported the preparation of [ 18 F]fluoroethylcholine (FECh) and DeGrado et al. the synthesis of [ 18 F]fluorocholine (FCH). Both syntheses require sophisticated purification step (preparative purification using ion-pair reagent for FECh and GC purification for FCH). We have designed an approach to prepare FECh and FCH that allows us to use the same equipment that produces FDG. Coenen et al. systematically studied the [ 18 F]fluorination of disubstituted alkanes and found that [ 18 F]fluoroethyl tosylate can be prepared in high yield from ditosylethane, while the corresponding [ 18 F]fluoromethyl tosylate can not prepared in useful yield. The 1-pot 2-step reaction started with [ 18 F]labeling of disulfonate alkane followed by fluorosulfonate intermediate's alkylation with dimethylethanolamine. [ 18 F]fluorination of ditosylethane proceeded efficiently (80%) while the alkylation step was surprisingly average. Thus, FECh overall yield was only 50%, decay corrected. [ 18 F]Fluorination of di-tosylmethane was more delicate. This step, when driven to completion, only yielde d [ 18 F]di-fluoromethane, not the mono-AcOH EtOH/ Water Dimethyl amine D itosyl K222/ Carbonate 3-W a y Valves Argon Reaction Vessel