Organocuprate-mediated alkylation of sugar epoxides. New stereospecific route to 3-C-alkyl-3-deoxy-α-D-glucose

Abstract

The reactivity of the 5,6-anhydroglucofuranose derivatives 1 and 3, readily prepared from D-glucose, toward different cyanocuprates was examined. The former epoxide led to the corresponding C-6 chainextended sugars, e.g., 2. Alkylation of 5,6-anhydro-3-deoxy-1,2-O-isopropylidene-α-D-erythro-hex-3-enofuranose 3 with mixed cyanocuprates RCu(CN)Li [R = Me, Bu] provided a convenient and stereospecific route to 3-C-alkyl (methyl, butyl)-3-deoxy-α-D-glucofuranose derivatives 12 and 14via 1,4-addition followed by hydroboration–oxidation.