Boat conformations synthesis, NMR spectroscopy, and molecular dynamics of methyl 4,6-O-benzylidene-3-deoxy-3-phthalimido-alpha-D-altropyranoside derivatives.
Addition of the elements of phthalimide to methyl 2,3-anhydro-4,6-O-benzylidene-alpha-D-mannopyranoside (1) under fusion conditions has yielded methyl 4,6-O-benzylidene-3-deoxy-3-phthalimido-alpha-D-altropyranoside (2). The conformation of the pyranose ring of 2 has been shown to be non-chair by 1H NMR spectroscopy, in contrast to the conformations of related derivatives having smaller substituents at C-3. Molecular dynamics simulations of 2 in explicit chloroform-d solvent have indicated four principal conformational possibilities. Of these, the 7C5/1S5 chair/skew boat form 2d has the lowest potential energy, and is largely consistent with the observed vicinal 1H-1H NMR coupling constants.
Coxon
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National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892-2720, USA. coxonb@mail.nih.gov
Reynolds
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RC
D002236:Carbohydrate Conformation; D003837:Deoxy Sugars / Q000737:chemistry*; D009038:Motion; D019906:Nuclear Magnetic Resonance, Biomolecular; D010797:Phthalimides / Q000737:chemistry*
D003837:Deoxy Sugars; D010797:Phthalimides; C438104:methyl 4,6-O-benzylidene-3-deoxy-3-phthalimido-altropyranoside