Green‐Light Photocatalytic Synthesis of Non‐Proteinogenic Isothiocyanate‐Decorated Amino Acids from Lysine Residues and Carbon Disulfide

A sustainable and mild approach for the synthesis of nonproteinogenic isothiocyanate‐decorated amino acids from lysine residues and carbon disulfide via green‐light photocatalysis is described. A series of pharmacologically interesting isothiocyanate‐containing amino acids and oligopeptides are synthesized for the first time through the desulfurization method with the wide tolerance of protected groups and amino acid residues. The produced unnatural amino acids can be successfully converted into thioamide‐containing amino acids such as thiocitrulline and its analogs. Mechanism studies support the dithiocarbamate radical coupling, deprotonation, and desulfurization processes. This approach expands the scope of nonproteinogenic amino acids and provides a new type of amino acid residues with a robust active site, which are significant organic building blocks and potential biological diagnostic markers.