1-O-Benzyl-2,3-O-isopropylidene-6-O-tosyl-α-l-sorbofuranose

In the title compound (systematic name: {(3aS,5S,6R,6aS)-3a-[(benzyloxy) methyl]-6-hydroxy-2,2-dimethyltetrahydrofuro[2,3-d][1,3]dioxol-5-yl}methyl 4-methylbenzenesulfonate), C23H28O8S, the absolute structure and relative stereochemistry of the four chiral centres have been established by X-ray crystallography, with the absolute configuration inferred from the use of l-sorbose as the starting material. The central furanose ring adopts a slightly twisted envelope conformation (with the C atom bearing the methylbenzenesulfonate substituent as the flap) from which three substituents depart pseudo-axially (-CH2 - O - benzyl, -OH and one acetonide O atom) and two substituents pseudo-equatorially (-CH2 - O - tosyl and second acetonide O atom). The dioxalane ring is in a flattened envelope conformation with the fused CH C atom as the flap. In the crystal, molecules pack in columns along [010] linked by O - H...O hydrogen bonds involving the furanose hydroxy group and furanose ether O atom.