RESUMO
The single-crystal X-ray diffraction and high-resolution 1H and 13C NMR spectral data for methyl 2,5-di-O-acetyl-beta-D-glucofuranosidurono-6,3-lactone and 1,2,5-tri-O-acetyl-beta-D-glucofuranurono-6,3-lactone are reported. The lactones were synthesized as byproducts of reactions carried out to obtain methyl 1,2,3,4-tetra-O-acetyl-D-glucopyranuronate. The conformations of these lactones in the crystal structure and in solution are discussed. A 1T2-like conformation was found to be the preferred form for these lactones in both the crystal lattice and in solution.
Assuntos
Glucosídeos/química , Lactonas/química , Oligossacarídeos/química , Configuração de Carboidratos , Cristalografia por Raios X , Glucosídeos/síntese química , Lactonas/síntese química , Espectroscopia de Ressonância Magnética , Modelos Moleculares , Estrutura Molecular , Oligossacarídeos/síntese química , Soluções/químicaRESUMO
Addition of hydrazoic acid to alpha,beta-unsaturated aldehydes derived from tri-O-acetyl-D-glucal and -D-galactal gave 3-azido-2,3-dideoxyhexopyranoses. These were converted into 1,4,6-tri-O-acetyl-3-azido-2,3-dideoxyhexopyranoses as well as methyl and ethyl glycosides. Hydrogenation of the proamine group in 3-azido-2,3-dideoxy derivatives provided different 3-amino and 3-acetamido sugars. The configuration and conformation of all products were established on the basis of the 1H and 13 C NMR, IR and polarimetric data.
Assuntos
Acetilglucosamina/síntese química , Desoxiaçúcares/síntese química , Desoxiglucose/análogos & derivados , Desoxiglucose/química , Galactose/análogos & derivados , Galactose/química , Hexoses/síntese química , Acetilglucosamina/análogos & derivados , Acetilglucosamina/química , Desoxiaçúcares/química , Hexoses/química , Rotação OcularRESUMO
Selective tosylation followed by acetylation of methyl 3-azido-2,3-dideoxy-alpha-D-arabino-hexopyranoside (1) in pyridine at room temperature affords a mixture of methyl 4-O-acetyl-3-azido-2,3-dideoxy-6-di-O-p-tolylsulfonyl-alpha-D-arabino-hexopyranoside (4) and methyl 3-azido-2,3-dideoxy-4,6-di-O-p-tolylsulfonyl-alpha-D-arabino-hexopyranoside (3). Compound 4 undergoes nucleophilic displacement with sodium iodide in acetic anhydride to give methyl 4-O-acetyl-3-azido-2,3,6-trideoxy-6-iodo-alpha-D-arabino-hexopyranoside (7), whose crystal structure and (1H) and (13)C NMR data are reported. This compound adopts the 4C(1) conformation.
