A simple synthesis of [C-11]dihydrotetrabenazine (DTBZ)

[C-11]Dihydrotetrabenazine (2-hydroxy-3-isobutyl-9-[C-11]methoxy-10-methoxy-1,2,3,4,6,7, -hexahydro-11bH-benzo[a]-quinolizine) ([C-11]DTBZ) was synthesized by re-acting the 9-hydroxy precursor in DMSO with gas phase [C-11]methyl iodide on a column of alumina impregnated with KOH. The reaction was instantaneous at room temperature. This column was then connected to the inlet of a short column containing basic alumina. Elution with cyclohexane removed radioactive contaminants. The radioactive product was then eluted with a few milliliters ether containing 1% ethanol. The [C-11]DTBZ was obtained in isolated yields of >200 mCi and specific activities >1600 Ci/mmol. (C) 1997 Elsevier Science Inc.