The labyrinthopeptins are a new class of lantibiotics containing two identical quaternary α,α-disubstituted amino acids, named labionin (Lab). The synthetic formation of this unique structural feature represents the key step in the total synthesis of these polycyclic peptides. In this report we describe the synthesis of an orthogonally protected α,α-disubstituted amino acid building block serving as labionin precursor for the future assembly of labyrinthopeptin A2 and of other labyrinthopeptin derivatives.

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