Radiosynthesis of carbon-11 labeled 6-methyldopamine ([11C]MeDA)

Abstract A rapid and efficient n.c.a. radiosynthesis of 6-[ 11 C]methyldopamine ([ 11 C]MeDA) using the Stille cross-coupling reaction as a key step was developed. The labeling conditions for the formation of the intermediate compound (protected [ 11 C]MeDA, [ 11 C] 7 ) were determined with respect to reaction temperature and time. The radiochemical yield 89±1.4% (decay-corrected) of the protected intermediate [ 11 C] 7 was obtained at a reaction temperature of 60 °C and a reaction time of 5 min using Pd 2 (dba) 3 /P( o -tolyl) 3 and CsF/CuBr as a co-catalyst system. The overall yield after deprotection with 45% HBr at 140 °C for 10 min was 64±3.9% (decay-corrected) within a total preparation time of 40 min, including hydrolysis, HPLC purification and formulation.