X-ray diffraction and high-resolution NMR spectroscopy of methyl 3,4-di-O-acetyl-1,5-anhydro-2-deoxy-D-arabino-hex-1-enopyranuronate.

Single-crystal X-ray diffraction and high-resolution (1)H and (13)C NMR spectral data for methyl 3,4-di-O-acetyl-1,5-anhydro-2-deoxy-D-arabino-hex-1-enopyranuronate are reported. The (5)H(4) conformation was found to be the preferred form for this glycal, both in the crystal lattice and in solution. The factors determining the (4)H(5)<==>(5)H(4) conformational equilibrium for acetylated glycals are discussed.

Conformations of methyl 2,5-di-O-acetyl-beta-D-glucofuranosidurono-6,3-lactone and 1,2,5-tri-O-acetyl-beta-D-glucofuranurono-6,3-lactone in the crystal structure and in solution.

The single-crystal X-ray diffraction and high-resolution 1H and 13C NMR spectral data for methyl 2,5-di-O-acetyl-beta-D-glucofuranosidurono-6,3-lactone and 1,2,5-tri-O-acetyl-beta-D-glucofuranurono-6,3-lactone are reported. The lactones were synthesized as byproducts of reactions carried out to obtain methyl 1,2,3,4-tetra-O-acetyl-D-glucopyranuronate. The conformations of these lactones in the crystal structure and in solution are discussed.

Synthesis and conformational studies on methyl 4-O-acetyl-3-azido-2,3,6-trideoxy-hex-5-enopyranosides of the L series.

Methyl 3-azido-2,3-dideoxy-alpha-D-xylo-, -alpha-D-lyxo-, and -beta-D-xylo-hexopyranosides were converted into 4-O-acetyl-3-azido-6-iodo-2,3,6-trideoxy analogues via 6-O-p-tolylsulfonyl compounds. The elimination of hydrogen iodide from 6-iodo glycosides yielded methyl 4-O-acetyl-3-azido-2,3,6-trideoxy-beta-L-erythro-, -alpha-L-threo-, and -beta-L-threo-hex-5-enopyranosides. The configuration and conformation of all products are evaluated in depth on the basis of (1)H and (13)C NMR data.