The <i>tert</i>-Butyl Side Chain: A Powerful Means to Lock Peptoid Amide Bonds in the Cis Conformation

The very simple sterically hindered tert-butyl side chain exerts complete control over the peptoid amide geometry which only exists in the cis conformation. It is exemplified in NtBu glycine homo-oligomers and in linear oligopeptoids designed with an alternating cis–trans backbone amide pattern.