Abstract: | The small synthetic peptide, benzyl 2‐(tert‐butoxycarbonyl‐amino)isobutyrate, C16H23NO4, has the α‐helical conformation |?| = 55.8 (2)° and |ψ| = 37.9 (2)°] observed in peptide fragments of peptaibols containing the α‐aminoisobutyric acid (Aib) residue. The structure shows no intramolecular hydrogen bonding, which would disrupt the limited conformational freedom associated with this amino acid. Two weak intermolecular hydrogen contacts are observed. |