New Preorganized γ-Amino Acids as Foldamer Building Blocks

An asymmetric synthesis of two new diastereomeric gamma-amino acids is described. Both molecules contain a cyclohexyl ring to limit conformational flexibility about the C-alpha-C-beta bond; they differ in having cis vs trans stereochemistry on the ring. Residues derived from the cis gamma isomer are shown to support helical secondary structures in alpha/gamma-peptide oligomers.