Synthesis of tritiated bumetanide

Abstract

SummarvTritium lahelled bumetanide of high specific activity (16 Ci/mmol) has been prepared in our lahoratory by tris(tripheny1phosphine) rhodium chloride catalyzed reduction of an olefinic precursor with carrier free tritium pas in benzene-ethanol (1:l). The product is labelled in the N-butyl side chain. Comparison of both heterogeneous palladium and homogeneous rhodium catalyzed deuterium reductions as a model for the tritiation revealed that the latter reduction was accompanied by considerably less label scrambling.