Benzophenone-Based Phenylogous Peptide Linkage via Friedel–Crafts Acylation

This study introduces a novel method to diversify peptide backbones by replacing conventional amide bonds with phenylogous (vinylogous) amide linkages using benzophenone units via Friedel-Crafts acylation, starting from vinylogous carboxylic acid (benzoic acid) and vinylogous amine (aniline). The reaction, optimized under acidic and low-temperature conditions, was applied to di- and tetrapeptides and displayed broad substrate compatibility. These modified peptides enable further transformations, including Beckmann rearrangement, to eventually restore conventional amide bonding. This strategy expands peptide structural diversity, providing new opportunities in drug discovery and non-natural peptide architecture designs.