Radiosynthesis of a selective dopamine D-1 receptor antagonist: R(+)-7-chloro-8-hydroxy-3-[11C]methyl-1-phenyl-2,3,4,5-tetrahydro-1H-3 -benzazepine ([11C]SCH 23390).

Carbon-11 labeled SCH 23390, a selective dopamine D-1 receptor antagonist (Fig. 1b), was prepared by N-alkylation of the nor-methyl precursor with [11C]iodomethane. The product was purified by semi-preparative HPLC and shown to be radiochemically pure at the end of synthesis. The synthesis was completed in approximately 22 min with an average radiochemical yield of 28% (based on [11C]iodomethane) and an average specific activity of approximately 1950 microCi/mumol calculated at the end of synthesis.