Radioiodination via solid phase organic chemistry

In principle, insoluble polymer-supported aryl stannanes provide a potentially convenient route to radioiodinated compounds for several reasons. Radioiododestannylation can proceed under mild conditions to provide no-carrier-added material that can be isolated by simple filtration from any insoluble unreacted starting material and from insoluble by-products. The final product should be free of tin impurities since the tin remains attached to the insoluble polymer. To convert principle to practice. we have been exploring the generality and usefulness of this approach. Through the use of appropriate protecting groups, several substituted phenyl rings have been bound through tin to the solid support. The meta and para substituents include hydroxy, methoxy, carboxyl, formyl and aminomethyl. Subsequent conversions of some of these groups have been attempted so that the aryl-stannanes can be used as precursors to libraries of radiopharmaceuticals. Conditions for radioiododestannylation have been investigated. In the specific case of the guanidinomethyl group, radioiodination leads to the release of MIBG (meta-iodobenzyl guanidinium) which has found use both diagnostically and therapeutically. [I-131]MIBG is produced in There Exists 90% radiochemical yield and high chemical purity with a reaction time of 5 minutes at room temperature and a total preparation time of about 10 minutes. [I-123]MIBG requires a temperature of -65 degrees for 5 minutes and again results in a product of There Exists 90% radiochemical yield and high chemical purity.