Non-innocent behaviour of aromatic isocyanides under visible light: a pathway to thioformimidates and dehydroalanine

Despite the significant potential of isocyanides to engage in reactions with thiyl radicals to produce nitrogen-containing organic molecules, their widespread use has been limited by the need for high-energy UV light activation. Herein, we disclose the synthesis of thioformimidates under mild reaction conditions employing visible light without additives. This study demonstrates the ability of aromatic isocyanides to generate thiyl radicals under visible light, functioning as radical intitators. Furthermore, the developed methodology reveals its utility in the selective activation of the thiol group in cysteine, which is subsequently converted to dehydroalanine, opening the door to late-stage peptide modification.