Measures and pitfalls for successful preparation of "no carrier added" asymmetric 6-[18F]fluor-L-dopa from 18F-fluoride ion.

6-[18F]Fluoro-L-dopa (6FD) has been proposed and used for probing cerebral dopamine metabolism by positron emission tomography. Recently a new method for asymmetric synthesis of 6FD has been reported. This method involves synthesis of 6-[18F]fluoro-3,4-dimethoxybenzylbromide which is reacted with (S)-1-Boc-2-tert-butyl-3-methyl-4-imidazolidinone. The resulting alkylated compound is then hydrolyzed with hydriodic acid to produce 6FD. This method has been used to produce 6FD and several critical steps that required attention found, in addition to some modification for successful 6FD production. 6FD is prepared in 6-13% radiochemical yield (decay not corrected) after HPLC purification with a production time of 85 min.