Three-Component Condensation Leading to β-Amino Acid Diamides: Convergent Assembly of β-Peptide Analogues

Abstract
A Passerini condensation of acyl cyanides, carboxylic acids, and isonitriles has been developed that affords efficient access to functionalized diamides as well as β-peptides of α-hydroxy-β-amino acids. Such compounds are protease-resistant and form stable helical and sheet structures when incorporated into larger peptides. N-Protected α-amino acids and isocyanoesters derived from α-amino acids participate in the condensation, leading to α/β peptides embodying the heterogeneous α/β/α backbone motif, recent examples of which display antibiotic activity.