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Details van artikel 192 van 252 gevonden artikelen
| Titel: |
Synthesis of L-Iduronic Acid Derivatives: Crystal Structure of Methyl (Methyl 2,3,4-Tri-O-Acetyl-β-L-Idopyranosid)Uronate |
| Auteur: |
Whitfield, Dennis M. Birnbaum, George I. Pang, Henrianna Baptista, Jose Sarkar, Bibudhendra |
| Verschenen in: |
Journal of carbohydrate chemistry |
| Paginering: | Jaargang 10 (1991) nr. 3 pagina's 329-348 |
| Jaar: |
1991 |
| Inhoud: |
Several L-iduronic acid derivatives were prepared by chemical synthesis including the reducing sugar, the α- and ss-methyl glycosides and L-iduronolactone. The ss-methyl glycoside, as well as two isomeric orthoesters, were the unexpected products of glycosylation of methyl (2,3,4-tri-O-acetyl-α-L-idopyranosyl bromide) uronate. EI-MS was used to distinguish between the orthoesters and the glycosides. The crystal structure of the ss-methyl glycoside was determined by direct methods and refined by full-matrix least squares to a final value of R = 0.067 for 1739 reflections. The pyran ring was found to occur in the 1C4 conformation, with the three acetoxy substituents in axial orientations. In aqueous solution, the α-anomer of the reducing sodium salt is almost entirely in a 2SO ring conformation and the α-methyl glycoside is an equilibrium mixture of conformations which is sensitive to pH: The ss-anomers all have spectral data consistent with predominant or only slightly distorted 1C4 chairs. |
| Uitgever: |
Taylor & Francis |
| Bronbestand: |
Elektronische Wetenschappelijke Tijdschriften |
Details van artikel 192 van 252 gevonden artikelen
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