Studies on the synthesis of peptides containing dehydrovaline and dehydroisoleucine based on copper-mediated enamide formation

• Franziska Gille and
• Andreas Kirschning

Beilstein J. Org. Chem. 2016, 12, 564–570, doi:10.3762/bjoc.12.55

• moieties present in the antibiotic myxovalargin is reported. Peptide formation is based on a copper-mediated C–N cross-coupling protocol between an acyl amide and a peptidic vinyl iodide. The presence of a neighboring arginine in the vinyl iodide posed a challenge with respect to the choice of the

• ornithine as well as for the tripeptide 44 containing dehydroisoleucine with the correct stereochemistry. Keywords: catalysis; dehydroamino acids; Hartwig–Buchwald reaction; myxovalargin; peptides; Introduction Dehydroamino acids [1] are rare amino acids that are constituents of many oligopeptides from

• microbial sources. Typical examples are myxovalargin (1), argyrin (2) and nisin (3, Scheme 1). Dehydroamino acids and peptides are characterized by the presence of an olefinic double bond conjugated with the carboxyl or peptidic carbonyl group. Besides being α,β-unsaturated acids or amides, respectively