Regiospecific incorporation of no-carrier-added radiobromine and radioiodine into aromatic rings via halogenodegermylation

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Abstract
A series of para-substituted aryltrimethylgermanium compounds have been used as model compounds with 77Br and 131I to assess the utility of no-carrier-added (n.c.a.) halogenodegermylation as a regiospecific halogenation method. With dichloramine-T as an oxidant, high radiochemical yields were rapidly obtained in both activated and deactivated ring systems using n.c.a. 131I with a variety of solvents at 25 °C. Use of n.c.a. 77Br resulted in high yields with activated systems in methanol at 25 °C, and with both activated and deactivated ring systems in the presence of acid or with warming. Halogenation was regiospecific in all cases. High yields, regiospecificity, rapid kinetics, and the low concentration of oxidant required make aromatic n.c.a. halogenodegermylation a useful method for labelling radiopharmaceuticals.