Photobromination of carbohydrate derivatives. Part 7. Reaction of furanose derivatives with bromine: 4′-bromo- and 4′-fluoro-aldofuranose and -nucleoside esters

Abstract

Photobromination of 1-O-acetyl-2,3,5,6-tetra-O-benzoyl-β-D-glucose or -D-galactose with bromine gives the same mixture of 4-monobrominated compounds from which the D-galacto-epimer can be isolated in ca. 70% yield. 1-O-Acetyl-2,3,5-tri-O-benzoyl-β-D-ribose similarly gives the 4-bromo-products; the D-ribo-isomer was isolated and the corresponding halogenated derivative was obtained from pentabenzoyladenosine. In each of these series 4-fluoro-analogues were obtained from the initial bromides.