Figure 13.

(A) Cysteine detection using chemoselective imidazolidino boronate (IzB)-cyclized peptide; (B) N-Terminal cysteine modification through TzB mediated acyl transfer reaction; (C) Conjugation of N-terminal cysteine (NCys) with 2-formylphenylboronic acid (2-FPBA) to afford a thiazolidine boronate (TzB) complex; (D) Coupling of AEP ligation with N-terminal cysteine trapping by 2-FPBA; (E) Site-selectively installing an iminoboronate using a boron hot-spot (BHS) strategy; (F) Modification of peptide using alkenyl boronic acid and sodium ascorbate; (G) Copper-mediated site-selective peptide arylation at the N-terminus.