title: Solid-phase synthesis of a branched hexasaccharide using a highly efficient synthetic strategy.
abstract: The solid-phase synthesis of branched lacto-N-neohexaose derivative 1 occurring in human milk is described. The new building block of lactose 3 bearing the orthogonal temporary hydroxy protecting groups 9-fluorenylmethyloxycarbonyl (Fmoc) and levulinoyl (Lev) has been prepared. Its use, together with that of lactosamine donor 4, glucosamine donor 5, and O-galactosyl trichloroacetimidate 6, has enabled the preparation of hexasaccharide 22 following two different approaches in excellent overall yield (43%, 90% per step over eight steps). An additional key feature of this work is the successful use of newly prepared ester-type linker 2, having a benzylic spacer connected to the anomeric oxygen. This linker presents the advantage of producing a benzylic anomeric moiety after cleavage from the polymer support, which could be easily removed to obtain the unprotected oligosaccharide 1.
authors.affiliation: Fachbereich Chemie, Universität Konstanz, Fach M 725, D-78457 Konstanz, Germany.
authors.forename: F
authors.initials: F
authors.lastname: Roussel
authors.forename: M
authors.initials: M
authors.lastname: Takhi
authors.forename: R R
authors.initials: RR
authors.lastname: Schmidt
mesh_terms: D002240:Carbohydrate Sequence; D003432:Cross-Linking Reagents; D004952:Esters / Q000737:chemistry; D005449:Fluorenes / Q000737:chemistry; D005944:Glucosamine / Q000737:chemistry; D007785:Lactose / Q000737:chemistry; D008895:Milk, Human / Q000737:chemistry; D008969:Molecular Sequence Data; D009844:Oligosaccharides / Q000138:chemical synthesis*
chemical_list: D003432:Cross-Linking Reagents; D004952:Esters; D005449:Fluorenes; D009844:Oligosaccharides; C054007:1-(9-fluorenyl)methyl chloroformate; D007785:Lactose; D005944:Glucosamine