Copper-mediated 77Br, 125I, and 211At radiohalogenation of aryl thianthrenium salts using visible light

This article describes a Cu-mediated visible-light ipso-radiohalogenation of thianthrenium salts with bromine-77, iodine-125 and astatine-211. Thianthrenium precursors provide late-stage, regioselective access to labelled (hetero)arenes, delivering radiohalides in moderate to high radiochemical yields within 1 min at room temperature. Notably, radioastatination proceeds without photocatalysts, revealing distinct photoreactivity. The optimised protocols were applied to functionally dense small molecules, including a methoxyestrone derivative featuring a steroidal template common in many radiopharmaceuticals.