6-[18F]Fluoro-L-DOPA by radiofluorodestannylation : A short and simple synthesis of a new labelling precursor

Article abstract of DOI:10.1002/(SICI)1099-1344(199802)41:2<105::AID-JLCR65>3.0.CO;2-H

This paper describes a short and simple synthesis of a new fully protected stannylated precursor, namely N-(tert-butoxycarbonyl)-3,4-di(tert-butoxycarbonyloxy)-6-trimethylstannyl-L -phenylalanine ethyl ester, for the preparation of 6-[¹⁸F]fluoro-L-DOPA, used routinely in our Positron Emission Tomography program on neurodegenerative diseases as a tracer of the cerebral dopamine metabolism. The chemical pathway described for the total synthesis of our labelling precursor uses a straightforward protection sequence. This 4-step chemical synthesis allows the rapid preparation of several grammes of pure material in good overall yield. Regioselective radiofluorodestannylation using [¹⁸F]fluorine ([¹⁸F]F₂, cyclotron-produced isotope, half-life : 110 min) gave pure 6-[¹⁸F]fluoro-L- DOPA (8) in good radiochemical yield (26% decay-corrected, based on starting [¹⁸F]fluorine recovered from the target) in 45-50 min after the End of Bombardment. The product was found to be >99% chemically, radiochemically and enantiomerically pure.