Radiobromine labeled norcholesterol analogs. Synthesis and tissue distribution study in rats of bromine-82 labeled 6beta-bromomethyl-19-norcholest-5(10)-EN-38-OL.

6beta-Bromomethyl-19-norcholest-5(10)-en-3beta-ol (NCL-6-Br) was synthesized directly from cholest-5-ene-3beta,19-diol 19-toluene-p-sulfonate via homoallylic rearrangement with ammonium bromide or sodium bromide in acetonitrile. This method was applied to the radiolabeling of NCL-6-Br with bromine-82. Tissue distribution of bromine-82 labeled NCL-6-Br (NCL-6-Br-82) in rats was determined. The mean percent dose per gram uptake in adrenal at 24 and 120 h was 98 and 80 %/gm, respectively, which indicated a higher adrenal uptake as compared to iodine-131 labeled 19-iodocholest-5-en-3beta-ol (CL-19-I-131), but was at a lower level than that achieved with iodine-131 labeled 6beta-iodomethyl-19-norcholest-5(10)-en-3beta-ol (NCL-6-I-131). The ratio of radioactivity in the adrenal-to-liver concentration was also lower than that of CL-19-I-131 or NCL-6-I 131.