RADIOSYNTHESIS OF~(18) F-FMTP

fluorobenzyl)-8-methoxy-1,2,3,4-tetrahydr ochromeno3,4- c pyridin-5-one(FMTP), a selective D 4 receptor antagonist, exhibits nanomolar affinity and high selectivity. 18 F-FMTP is synthesized in multistep reactions in which fluorine-18 is introduced by nucleophilic halogen displacement on a quaternary ammonium group precursor. The fluorine-18 labeled intermediate is subsequently reductively aminated with 8-methoxy-1,2,3,4-tetrahydrochromeno3,4- c pyridin-5-one to form the final products. The radiosynthesis of 18 F-FMTP needs approximatively 110 min with an overall radiochemical yield of 19.5%(decay-corrected) and with highly effective specific activities(>37 GBq/μmol). 18 F-FMTP may be a useful positron emission tomography (PET) tracer that can be applied to map brain dopamine D 4 receptor.