β-nitro-α-amino acids as latent α,β-dehydro-α- amino acid residues in solid-phase peptide synthesis

β-Nitro-α-amino acids, that are readily accessible through either the reaction of bromoglycine derivatives with alkyl nitronates or the three-component coupling of amines, nitroalkanes and glyoxalate in aqueous base, are easily converted to the corresponding N-t-Boc-amino acids. These undergo solid-phase Merrifield peptide synthesis, with elimination of nitrous acid, either during or subsequent to cleavage of the peptide from the resin, converting the nitro amino acids to dehydro amino acid residues. The method has been applied successfully with two β,β-disubstituted nitro amino acids and N-methyl-β-nitronorvaline, but failed with β-nitroalanine.