RADIOIODODESTANNYLATION - PREPARATION OF RADIOIODINATED VINYL ALCOHOLS AND SELECTED EVALUATION IN RATS

Radioiododestannylation has been employed to prepare a series of radio iodinated vinyl alcohols, two of which were evaluated for their tissue distribution in rats. The radioiodination method utilized tri-alkylst annylvinyl intermediates that can be prepared in good yields from 1,2- bis(tributylstannyl) ethylene and the appropriate ketones or by hydros tannation of the corresponding ethynyl alcohols. The radiolabeling pro ceeded at the no-carrier-added level to give, after HPLC separation, t he desired products in 85-95% isolated yields. Tissue distribution stu dies in the rat indicated that the agents were rapidly extracted by th e brain and then quickly cleared. No retention of activity was observe d in the nonmetabolizing or nonexcretory organs. Chemically, the use o f the E-tributylstannylvinyl lithium followed by radioiodination contr olled stereochemistry and eliminated the separation of E- and Z-iodovi nyl isomers. Biologically, the compounds behaved as neutral, diffusibl e and nonmetabolized radiotracers that may be used for the evaluation of cerebral blood flow, potentially with the short-lived radionuclide I-122 or other short-lived radiohalogens.