Metal‐free sp 2 ‐C7−H Borylation of Tryptophan Containing Peptides and Late‐stage Modification

The discovery of milder and robust strategies to enable the introduction of organoboronates in peptides remains conspicuously underdeveloped. Herein, we demonstrate an efficient method for the site‐selective sp 2 ‐C7−H borylation of tryptophan under metal‐free condition using BBr 3 directed by pivaloyl group. The versatility of this approach is that gram scale synthesis and C7‐borylated N ‐Phth‐Trp( N ‐Piv)(C7‐BPin)‐OMe was modified into various C7‐substituted derivatives. Moreover, the strategy enables for the peptide elongation and late‐stage borylation of peptides, natural product Brevianamide F and drug Oglufanide.