title: Synthesis of highly condensed polycyclic carbohydrates by reaction of a spirocyclic enamino sulfonate derived from d-xylofuranose with bifunctional reagents.
abstract: The appropriately substituted 5-O-tosyl derivative (1), easily prepared from 1,2-O-isopropylidene-alpha-d-xylofuranose, serves as a useful precursor for the preparation of highly condensed cyclic carbohydrates. The synthesis involves a first cyclization of the 5-O-tosyl sugar derivative 1 to a highly reactive cyclic enamine, which subsequently undergoes the nucleophilic attack of a bifunctional reagent X(CH2)nZ in a regio- and stereospecific way. Finally, a spontaneous cyclization step allows the formation of a stereochemically defined extra ring, fused to the sugar backbone. The functionalization and size of this ring can be varied by the proper choice of the bifunctional reagent. X-ray diffraction analysis and intensive NMR studies with one of these carbohydrates were performed to highlight the strained nature of these compounds.
authors.affiliation: Instituto de Química Médica (CSIC), Juan de la Cierva 3, 28006 Madrid, Spain.
authors.forename: Alessandra
authors.initials: A
authors.lastname: Cordeiro
authors.forename: María Luisa
authors.initials: ML
authors.lastname: Jimeno
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Maestro
authors.forename: María-José
authors.initials: MJ
authors.lastname: Camarasa
authors.forename: Ernesto
authors.initials: E
authors.lastname: Quesada
authors.forename: Ana
authors.initials: A
authors.lastname: San-Félix
mesh_terms: D000476:Alkanesulfonates / Q000138:chemical synthesis / Q000737:chemistry*; D002241:Carbohydrates / Q000138:chemical synthesis* / Q000737:chemistry; D018360:Crystallography, X-Ray; D007202:Indicators and Reagents / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods / Q000592:standards; D008958:Models, Molecular; D008968:Molecular Conformation; D012015:Reference Standards; D013141:Spiro Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D013237:Stereoisomerism; D014994:Xylose / Q000031:analogs & derivatives* / Q000737:chemistry*
chemical_list: D000476:Alkanesulfonates; D002241:Carbohydrates; D007202:Indicators and Reagents; D013141:Spiro Compounds; D014994:Xylose