Influence of the oxime and anomeric configurations on the stability of 2-deoxy-2-hydroxyimino-d-hexopyranosides

• Benzyl 2-deoxy-2-hydroxyimino-d-hexopyranosides were synthesized.
• The E/Z oxime isomerization was observed.
• DFT optimizations for the α-Z, α-E, β-Z the β-E stereoisomers were performed.
• Tendency to E/Z oxime isomerization is indicated.
• X-Ray analysis and NMR spectra confirm our theoretical studies.

The Z/E isomerisations of the synthesized benzyl 3,4,6-tri-O-acetyl-2-deoxy-2-hydroxyimino-d-hexopyranosides during the NMR measurement and during the Zemplén O-deacetylation were observed. In order to study stabilities and tendency of the obtained compounds to isomerise, B3LYP/6-311++G∗∗ level geometry optimisations for four stereoisomers of methyl 2-deoxy-2-hydroxyimino-d-arabino-hexopyranosides in both the O-acetylated and O-deacetylated forms were performed. The results of our theoretical studies are fully in agreement with the experimental data and NMR analysis. Additionally, a single-crystal X-ray diffraction data for benzyl 2-deoxy-2-hydroxyimino-α-d-lyxo-hexopyranoside are reported to supplement our theoretical studies.

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