Synthesis of 4-Azido-4-deoxy-Neu5,7,8,9Ac42en1Me. A Key Intermediate for the Synthesis of GG167 from d-Glucono-δ-lactone

Stereoselective synthesis of 5-acetamido-7,8,9-tri-O-acetyl-2,6-anhydro-4-azido-3,4,5-trideoxy-d-glycero-d-galacto-non-2-enonic acid methyl ester, an advanced key intermediate for the synthesis of neuraminidase inhibitor GG167 (Zanamivir, Relenza), was accomplished using d-glucono-δ-lactone as starting material. A highly diastereoselective allyllation of an imine intermediate, a regioselective azide-opening of an aziridine, and chemoselective oxidations of vicinal diols served successfully as key steps.