6-[F-18]FLUORO-L-DOPA BY RADIOFLUORODESTANNYLATION - A SHORT AND SIMPLE SYNTHESIS OF A NEW LABELING PRECURSOR

This paper describes a short and simple synthesis of a new fully prote cted stannylated precursor, namely xycarbonyloxy)-6-trimeth-ylstannyl- L-phenyiaianine ethyl ester, for the preparation of 6-[F-18]fluoro-L-D OPA, used routinely in our Positron Emission Tomography program on neu rodegenerative diseases as a tracer of the cerebral dopamine metabolis m The chemical pathway described for the total synthesis of our labell ing precursor uses a straightforward protection sequence. This I-step chemical synthesis allows the rapid preparation of several grammes of pure material in good overall yield. Regioselective radiofluorodestann ylation using [F-18]fluorine ([F-18]F-2, cyclotron-produced isotope, h alf-life : 110 min) gave pure 6-[F-18]fluoro-L-DOPA (8) in good radioc hemical yield (26% decay-corrected, based on starting [F-18]fluorine r ecovered from the target) in 45-50 min after the End of Bombardment. T he product was found to be >99% chemically, radiochemically and enanti omerically Fu!e.