Synthesis of α‑C-Galactosylceramide via Diastereoselective Aziridination: The New Immunostimulant 4′-epi-C-Glycoside of KRN7000

A new immunostimulant, the 4′-epimer of α-C-GalCer, was synthesized from a C 2-symmetric dienediol and α-C-allyl galactoside. The intramolecular aziridination and the following reductive ring opening provided the core of the aliphatic amino alcohol with excellent regio- and stereocontrol. The new immunostimulants 3d and 3e gave a better polarized Th1-type cytokine response in murine NKT cells than the benchmarked α-C-GalCer.