Novel C-3 Epimerization of Glycals by Metal Chlorides
Treatment of tri-O-acetyl-D-glycals, e.g., tri-O-acetyl-D-glucal, tri-O-acetyl-D-allal and tri-O-acetyl-D-galactal, with metal chlorides in acetic anhydride afforded the C-3 epimer of the glycal triacetate with pseudo-glycal triacetate and unreacted glycal triacetate as an equilibrium mixture.The C-3 epimer of the glycal was readily separated from the reaction mixture using preparative HPLC.