Abstract
| - An efficient epimerization-free route toward β,β-disubstitutedβ-amino acid-containing peptides isdescribed. The methodology involves the use of4,4-disubstituted-N-Boc β-lactams asacylatingagents, which upon coupling with amino acid esters, promoted bypotassium cyanide, give rise todipeptides with no appreciable racemization. By this procedureshort peptide segments containinga four-, five-, or six-membered ring at the β-position of theβ-amino acid residue have been prepared.The method has also proven to be valuable for the preparation oftripeptides. In addition thesterically hindered amino terminus of the β-amino acid can undergopeptide couplings understandard conditions.
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