A synthesis of nikkomycin Z: Improved synthesis and protection of the pyridyl γ-hydroxy-α-aminobutanoic acid component

The first synthesis of nikkomycin Z is described. An improvement of the isoxazoline-based methodology, and an effective method for protection of 1b were devised. The application of oxalyditriazole (23) for peptide coupling proved most effective in completing the synthesis. A new and efficient synthesis of the prorequisite pyridyl E-olefin (5) is also described.