In situ Generation of Quinoliziniums for Dual Visible Light‐induced Gold(III)‐catalyzed Alkynylation and Peptide Modification

Abstract A new approach of dual visible light‐induced gold(III)‐catalyzed alkynylation and its application in selective modification of alkyne‐linked peptides has been developed. The bis‐cyclometalated gold(III) complex exhibited dual roles of (1) in situ generation of quinolizinium‐based photosensitizer (λ em =500 – 594 nm) and (2) alkynylation of iminium ions. Under optimized conditions, alkynylated products were afforded in good yields up to 73 %. The application of this strategy in selective modification of alkyne‐linked peptides gave modified peptides in up to 67 % conversion. Our dual visible light/gold(III) catalysis exemplifies the potential of merging photocatalysis and transition metal catalysis to develop novel bioconjugation.