Synthesis of (E)-4-[4,4-dimethyl-2,5-dioxo-3-{1 '-(125I)iodo-1 '-propen-3 '-yl}-1-imidazolidinyl]-2-trifluoromethylbenzonitrile: A potential radioligand for the androgen receptor

The synthesis of a novel radioiodinated nonsteroidal androgen receptor liga nd (E)-4-[4,4-dimethyl-2,5- -dioxo-3-{1'-(I-125)iodo-1'-propen-3'-yl}-1-imi dazolidinyl]-2-trifluoromethylbenzonitrile ([I-125](1) under bar) is descri bed. In vitro competitive binding studies demonstrated that (1) under bar b ound to the rat androgen receptor with high affinity (Ki = 13 nM). No-carri er-added [1251](1) under bar was synthesized from the corresponding tri-n-b utyltin precursor by an oxidative radioiododestannylation reaction with Na[ I-125]iodide and 3% aqueous hydrogen peroxide as oxidant. Subsequent HPLC p urification provided [I-125](1) under bar in 86-92% (average = 90%; n = 5) isolated radiochemical yields having >99% radiochemical and chemical purity and a specific activity range of 1574-1835 Ci/mmol (average = 1733 Ci/mmol ; n = 3).