Internal Peptide Late-Stage Diversification: Peptide-Isosteric Triazoles for Primary and Secondary C(sp3 )-H Activation.

Secondary C(sp3 )-H arylations were accomplished by palladium catalysis with triazoles as peptide bond isosteres. The unique power of this approach is highlighted by the possibility of achieving secondary C(sp3 )-H functionalizations on terminal peptides as well as the unprecedented positional-selective C(sp3 )-H functionalization of internal peptide positions, setting the stage for modular peptide late-stage diversification.