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Title: Conformational analysis of the disaccharide methyl α- D -mannopyranosyl-(1→3)-2- O -acetyl-β- D -mannopyranoside monohydrate
The crystal structure of methyl α-D-mannopyranosyl-(1→3)-2- O -acetyl-β-D-mannopyranoside monohydrate, C 15 H 26 O 12 ·H 2 O, ( II ), has been determined and the structural parameters for its constituent α-D-mannopyranosyl residue compared with those for methyl α-D-mannopyranoside. Mono- O -acetylation appears to promote the crystallization of ( II ), inferred from the difficulty in crystallizing methyl α-D-mannopyranosyl-(1→3)-β-D-mannopyranoside despite repeated attempts. The conformational properties of the O -acetyl side chain in ( II ) are similar to those observed in recent studies of peracetylated mannose-containing oligosaccharides, having a preferred geometry in which the C2—H2 bond eclipses the C=O bond of the acetyl group. The C2—O2 bond in ( II ) elongates by ∼0.02 Å upon O -acetylation. The phi (φ) and psi (ψ) torsion angles that dictate the conformation of the internal O -glycosidic linkage in ( II ) are similar to those determined recently in aqueous solution by NMR spectroscopy for unacetylated ( II ) using the statistical program MA′AT , with a greater disparity found for ψ (Δ = ∼16°) than for φ (Δ = ∼6°).  more » « less
Award ID(s):
1707660
NSF-PAR ID:
10097487
Author(s) / Creator(s):
; ; ;
Date Published:
Journal Name:
Acta Crystallographica Section C Structural Chemistry
Volume:
75
Issue:
6
ISSN:
2053-2296
Page Range / eLocation ID:
610 to 615
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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