Fluorocarbohydrates. Part XI. Formation of a cis-addition product in the bromofluorination of tri-O-acetyl-D-galactal

Abstract

Treatment of triacetyl-D-galactal with N-bromosuccinimide and hydrogen fluoride in ether at –70° led to a mixture of adducts from which crystalline 2-bromo-2-deoxy-α-D-galactopyranosyl fluoride was obtained by deacylation with sodium methoxide. The structure of the bromofluoride was shown by alkaline hydrolysis to 2,3-anhydro-α-D-talopyranosyl fluoride, and by methanolysis to methyl 2-bromo-2-deoxy-β-D-galactoside from which the known methyl 2,3-anhydro-β-D-talopyranoside was prepared.