Water compatible photoarylation of amino acids and peptides.

A novel photoarylation of amino acids and peptides is described, which tolerates the presence of water. Irradiation of Boc-protected amino acids in the presence of N-protected 2-azidobenzimidazoles leads to selective arylation of carboxy termini or side chains. The new reaction also works for peptides. Irradiation of the nonapeptide H-SPSYVYHQF-OH also resulted in selective arylation of the tyrosine side chains, as indicated by ESI-MS/MS fragmentation. Chemo- and regioselectivity could add the title reaction to the repertoire of photoaffinity labeling methods.