2,3:4,6-Di-O-isopropylidene-α-L-sorbofuranose and 2,3-O-isopropylidene-α-L-sorbofuranose

Journal article, 2009

In the title compounds, C12H20O6, (I), and C9H16O6, (II), the five-membered furanose ring adopts a 4T3 conformation and the five-membered 1,3-dioxolane ring adopts an E3 conformation. The six-membered 1,3-dioxane ring in (I) adopts an almost ideal OC3 conformation. The hydrogen-bonding patterns for these compounds differ substantially: (I) features just one intramolecular O-H...O hydrogen bond [O...O = 2.933 (3)Å], whereas (II) exhibits, apart from the corresponding intramolecular O-H...O hydrogen bond [O...O = 2.7638 (13)Å], two intermolecular bonds of this type [O...O = 2.7708(13) and 2.7730(12) Å]. This study illustrates both the similarity between the conformations of furanose, 1,3-dioxolane and 1,3-dioxane rings in analogous isopropylidene-substituted carbohydrate structures and the only negligible influence of the presence of a 1,3-dioxane ring on the conformations of furanose and 1,3-dioxolane rings. In addition, in comparison with reported analogs, replacement of the -CH2OH group at the C1-furanose position by another group can considerably affect the conformation of the 1,3-dioxolane ring.