6-[Bis(ethoxycarbonyl)methyl]-6-deoxy-1,2;3,4-di-O-isopropylidene-d-galactopyranose

The title compound, C19H30O9, was prepared by substitution at the C6 position in 1,2;3,4-di-O-isopropylidene-6-O-trifluoromethanesulfonyl-d-galactose using sodium ethoxymalonate in dimethylformamide. The conformation is skew-boat 0S2, slightly distorted towards boat B2,5. The inflexible pyranose structure makes the title compound a suitable intermediate for further synthetic work by keeping stereogenic carbon atoms safe from inversion. Several short intramolecular C—H... O contacts may stabilize the conformation of the molecule. Intermolecular C—H...O interactions also occur.