Synthesis of the Threoglucin 1,3-Oxazinane Core via Cyclothreonine Rearrangement

Cyclization of serine and threonine-containing <i>N</i>-hydroxy dipeptides under Mitsunobu conditions affords 1,3-oxazinanes via N-acylimine intermediates. Synthesis of the heterocyclic core of the threoglucin family of antibiotics proceeds in high yield to afford the α-quaternary amidoketal dipeptide. The described method provides convenient entry into a new class of constrained peptides featuring Cα-heteroatom substitution.