Screw sense alone can govern enantioselective extension of a helical peptide by kinetic resolution of a racemic amino acid.

Helical peptides built principally from the achiral quaternary amino acid Aib but with an induced preferred screw-sense exhibit enantioselectivity in their chain-extension reactions when presented with a racemic tertiary amino acid. This is the first demonstration that secondary structure alone, in the absence of local chiral residues, can direct the enantioselectivity of peptide coupling.