A new approach to obtaining Nα -t-Boc-amino acid aldehydes from asparagine and glutamine for reduced amide pseudopeptide solid-phase synthesis.

ABSTRACT

Reduced amide pseudopeptides have been proposed as structural probes that could be useful as potential malarial vaccine components. However, designing determined pseudopeptide sequences containing isoster peptide bonds, either on an asparagine (Asn) or on a glutamine (Gln) residues, can become difficult because these precursor amino acid aldehydes are obtained in yields lower than 0.5%. This work presents a new strategy for obtaining both Asn and Gln aldehydes based on a controlled side-chain protection approach as well as a suitable solvent partition procedure. FT-IR, (1) H-NMR and (13) C-NMR were used for molecule characterization and identification. Amino acid aldehydes were successfully incorporated into a 20-mer peptide from a malarial-relevant sequence, and their impact on the molecule's conformational properties was assessed.