U. Ackermann, H. Tochon-Danguy, A. Scott
Jul 1, 2004
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0
Influential Citations
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Journal
Journal of Labelled Compounds and Radiopharmaceuticals
Abstract
A novel way of preparing 11C labelled methyl esters using [11C]methanol and either BF3 etherate or trimethylsilyl chloride as catalyst was investigated. Radiochemical yields with BF3 etherate were between 30 and 33% for [11C]methyl benzoate and less than 1% for [11C]methyl thio salicylate. No [11C]methyl ester formation could be observed with trimethylsilyl chloride for all compounds investigated. This method is an alternative to using [11C]methyl iodide in the presence of a base. It is particularly suited for carboxylic acids bearing functional groups which would compete for [11C]methyl iodide, thus eliminating the need to introduce protecting groups. However, o-anisic acid formed [11C]methyl salicylate in 33–30% decay corrected radiochemical yield due to hydrolytic cleavage of the methyl ether, and none of the desired [11C]methyl 2-methoxy benzoate could be obtained. When salicylic acid was used as starting material, [11C]methyl salicylate could only be obtained in 5–8% decay corrected radiochemical yield. Copyright © 2004 John Wiley & Sons, Ltd.