13C, 15N CP MAS and high resolution multinuclear NMR study of methyl 3,4,6-tri-O-acetyl-2-(3′-arylureido)-2-deoxy-β-d-glucopyranosides

Four new derivatives of methyl 3,4,6-triacetyl-2-deoxy-(3′-arylureido)-β-d-glucopyranoside were studied by 1H, 13C, 15N NMR in CDCl3 solutions and by 13C, 15N NMR in the solid state. The replacement of one aryl substituent by another has no influence on the proton and carbon chemical shifts within the sugar moiety, in solution. The differences in 13C chemical shifts Δ = δliquid - δsolid are significant for C-3 (deshielding of -3.4 to -3.8 ppm), C-5 and OMe but not observed for C-2, where the ureido substituent is linked, thus indicating that this fragment of the structure is rigid. The values of Δ in 15N chemical shifts of N-3′ are -2.3 to -2.8 ppm (increase of shielding in the solids); the effect of replacement of substituent at aromatic ring is larger than the contribution of intermolecular H-bond interaction. The values of 15.5–16.1 Hz for 1JC-1′-N and 21.2–21.5 Hz for 1JCO-N indicate that the two CN-3′ bonds are of significant double bond character.