Catalytic, One-Pot Synthesis of β-Amino Acids from α-Amino Acids. Preparation of α,β-Peptide Derivatives

The one-pot conversion of readily available α-amino acid into β-amino acid derivatives was carried out in good yields. The method is a sequential process initiated by a tandem radical decarboxylation−oxidation reaction; the resulting acyliminium ion was trapped by silyl ketenes. Stoichiometric and catalytic versions of this reaction were developed and then applied to prepare modified di- and tripeptides. Interestingly, some tripeptides formed expanded β-turns in the solid state.