Synthesis and enzymatic decarboxylation of 6‐bromo‐L‐dopa, a potential brain tracer for L‐dopa

Direct bromination of L‐dopa with stoichiometric amounts of molecular bromine was found to yield 6‐bromo‐L‐dopa as the sole product. This determination was made using liquid chromatography with electrochemical detector, mass spectroscopy, and proton NMR. 6‐Bromo‐L‐dopa was found to be a substrate of an isolated decarboxylase enzyme although the rate of decarboxylation was much slower than that for L‐dopa. These results suggest that a radiobrominated L‐dopa analog may be a suitable PET or SPECT tracer for L‐dopa in the brain.