SYNTHESIS AND STRUCTURE OF 1,4 3,6-DIANHYDRO-2-O-P-TOSYL-D-MANNITOL/

1,4:3,6-Dianhydro-2-O-p-tosyl-D-mannitol (3) has been isolated from th e reaction of 1,4:3,6-dianhydro-D-mannitol (2) and p-toluenesulfonyl c hloride (1:2 mole ratio) in pyridine in 19% yield after fractional cry stallization. It crystallizes in the orthorhombic space group P2(1)2(1 )2(1) (Z = 4) With a = 6.064(2), b = 8.347(1) and c = 26.455(16) Angst rom. 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 c onformations of the unsubstituted furanose ring with the weaker intram olecular II-bonding (ring B) and the tosyl-substituted ring (ring A) a re very similar, being 1:2 mixtures of envelope [E-3] and twist forms [T-3(4)]: the stronger H-bonding in ring C results instead in a confor mation made up from a 30:70 mixture of E-o and T-4(o) forms. The H-1-N MR spectrum for 3 indicates that the average solution conformation is also a mixture of envelope and twist forms and is similar to that of t he A/B solid-state arrangement.