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

A rapid and efficient n.c.a. radiosynthesis of 6-[C-11]methyldopamine ([C-11]MeDA) using the Stille cross-coupling reaction as a key step was developed. The labeling conditions for the formation of the intermediate compound (protected [C-11]MeDA, [C-11]7) were determined with respect to reaction temperature and time. The radiochemical yield 89 +/- 1.4% (decay-corrected) of the protected intermediate [C-11]7 was obtained at a reaction temperature of 60 degrees 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 degrees C for 10 min was 64 +/- 3.9% (decay-corrected) within a total preparation time of 40 min, including hydrolysis, HPLC purification and formulation. (C) 2012 Elsevier Ltd. All rights reserved.