Boc-SPPS: Compatible Linker for the Synthesis of Peptide o-Aminoanilides

A protection strategy is described for the efficient synthesis of peptide o-aminoanilides using in situ neutralization protocols for Boc-SPPS. On-resin protection of Boc-protected aminoacyl o-aminoanilides is achieved with 2-chlorobenzyl chloroformate. Activation through a peptidyl-benzotriazole intermediate allows for facile conversion to peptide-thioesters for use in native chemical ligation. In addition to providing a robust alternative to established thioester resins, as a latent thioester, the peptide o-aminoanilide has broad utility in convergent ligation strategies.