title: 13C CP MAS NMR study of ureido sugars, derivatives of 2-amino-2-deoxy-beta-D-glucopyranose and dipeptides.
abstract: 3C CP MAS NMR spectra of solid methyl 3,4,6-tri-O-acetyl-2-deoxy-2-ureido-beta-D-glucopyranosides with dipeptide residues (protected by OMe, OEt or OBz group) were recorded. Broader resonances enabled assignment of carbons linked to nitrogen. Chemical shifts of sugar carbons varied within 2-6 ppm although the acetylated glucose moiety is the same in all compounds. From the six carbonyl groups in the molecule only the resonances of N6-C5=O are shifted by 2.9-8.3 ppm downfield in the spectra of solid compounds, comparing to the solution, indicating that the molecules are linked by NH...O=C5 hydrogen bonds. The C2=O group of ureido bridge is not involved in H-bonding, ester group probably forms intramolecular H-bonds.
authors.affiliation: Faculty of Pharmacy, Medical Academy, Warsaw, Poland.
authors.forename: I
authors.initials: I
authors.lastname: Wawer
authors.forename: B
authors.initials: B
authors.lastname: Piekarska-Bartoszewicz
authors.forename: A
authors.initials: A
authors.lastname: Temeriusz
authors.forename: M
authors.initials: M
authors.lastname: Potrzebowski
authors.forename: W
authors.initials: W
authors.lastname: Ciesielski
mesh_terms: D002241:Carbohydrates / Q000737:chemistry*; D002247:Carbon Isotopes; D004151:Dipeptides / Q000737:chemistry*; D005944:Glucosamine / Q000737:chemistry*; D006860:Hydrogen Bonding; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008958:Models, Molecular; D015394:Molecular Structure; D014508:Urea / Q000031:analogs & derivatives*
chemical_list: D002241:Carbohydrates; D002247:Carbon Isotopes; D004151:Dipeptides; D014508:Urea; D005944:Glucosamine