FACILE RADIOLABELING AND PURIFICATION OF TA-[O-(CH3)-C-11]-CARBOMETHOXY-3-BETA-ARYLTROPANES - RADIOTRACERS FOR THE DOPAMINE TRANSPORTER

Two potent dopamine transporter ligands, -C-11]-carbomethoxy-3-beta-(4 -methylphenyl)tropane and its 4-chlorophenyl analogue, were synthesize d by O-alkylation at the 2beta-carboxy position with [C-11]-iodomethan e. Separation of the [C-11]-labelled tropane from excess carboxylic ac id precursor was readily achieved by semipreparative HPLC providing pu re radiotracers at high specific activities (800-3000 mCi/mumole) suit able for in vivo PET studies. Radiosynthesis of this class of compound s by [O-(CH3)-C-11]-methylation offers advantages over previously repo rted [N-(CH3)-C-11]-methylation methods.