Synthesis of the Peptide Fragment of Pseudobactin

Article abstract of DOI:10.1021/jo00112a009

Synthesis of the peptide fragment, L-Lys-D-threo-β-OH-Asp-L-Ala-D-allo-Thr-L-Ala-N-OH-D-cOrn, of pseudobactin (2) is reported.By utilizing 2-ethoxy-1-(ethoxycarbonyl)-1,2-dihydroquinoline (EEDQ) as a coupling reagent, peptide bonds were constructed without requiring protection of hydroxyl groups.To access the D-allo-Thr residue in the peptide fragment of pseudobactin, the Thr residue in N-Cbz-L-Ala-D-Thr-L-Ala-O-t-Bu (4b) was converted to a peptidyl oxazoline using Burgess' reagent.Hydrolysis of the oxazoline with 1 N HCl followed by base-catalyzed acyl migration then provided the D-allo-Thr analog 4a.