Synthetic studies toward the mannopeptimycins: synthesis of orthogonally protected beta-hydroxyenduracididines

The asymmetric synthesis of the nonproteinogenic amino acids (2S,3S,4'S)-beta-hydroxyenduracididine 3 and (2R,3S,4'S)-beta-hydroxyenduracididine 4 in orthogonally protected form in 15 total steps from Garner's aldehyde is reported. The former and N-glycosylated form of the latter are found in the glycopeptide antibiotic mannopeptimycin.