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

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. © 1998 John Wiley & Sons, Ltd.