Patent ID: 8586570

Claim:
A peptide comprising an amino acid residue, a side chain of the amino acid residue reacted with a compound of structure (I): wherein R 1 is hydroxy, amino, or thiol; R 2 and R 3 are each independently hydrogen, an electron-withdrawing group, or —SO 2 X; each R 4 is independently hydrogen, an electron-withdrawing group or —SO 2 X, wherein R 4 can substitute any open valence of any ring within structure (I); X is —OR′ or —NR′R″; Y is a moiety that reacts with the side chain of an amino acid residue of the peptide to produce a thioether linkage between structure (I) and the side chain of the amino acid residue of the peptide; R′ and R″ are each independently hydrogen or C 1-6 alkyl; n is 0, 1, 2 or 3; and m is 1, 2 or 3, 4, and wherein at least one of R 2 , R 3 or R 4 is —SO 2 X.