Synthesis and structure of 1,4:3,6-dianhydro-2-O-p-tosyl-D-mannitol

Article abstract of DOI:10.1007/BF02575984

1,4:3,6-Dianhydro-2-O-p-tosyl-D-mannitol (3) has been isolated from the reaction of 1,4:3,6-dianhydro-D-mannitol (2) and p-toluenesulfonyl chloride (1:2 mole ratio) in pyridine in 19% yield after fractional crystallization. It crystallizes in the orthorhombic space group P2₁2₁2₁ (Z = 4) with a = 6.064(2), b = 8.347(1) and c = 26.455(16) A. Disorder associated with the unsubstituted furanose ring provides two arrangements, rings B and C, with two sets of sites for both the hydroxyl group and a ring carbon atom: the relative occupancy of ring B: ring C = 0.53(1):0.47(1). Distinct H-bonding situations (both intra- and inter-molecular) are associated with the two arrangements. The conformations of the unsubstituted furanose ring with the weaker intramolecular H-bonding (ring B) and the tosyl-substituted ring (ring A) are very similar, being 1:2 mixtures of envelope [³E] and twist forms [³T₄]: the stronger H-bonding in ring C results instead in a conformation made up from a 30:70 mixture of E₀ and ⁴T₀ forms. The ¹H-NMR spectrum for 3 indicates that the average solution conformation is also a mixture of envelope and twist forms and is similar to that of the A/B solid-state arrangement.