title: Stereoselective synthesis of β-d-GlcNAc-(1→4)-D-Glc disaccharide starting from lactose.
abstract: The stereoselective preparation of the β-d-GlcNAc-(1→4)-D-Glc disaccharide starting from known 4-O-[6-O-(1-methoxy-1-methylethyl)-3,4-O-isopropylidene-β-d-talopyranosyl]-2,3:5,6-di-O-isopropylidene-aldehydo-D-glucose dimethyl acetal (2), in turn easily obtained from lactose, is reported. Key steps of this new procedure, that avoids the glycosylation reaction, are (a) a first epimerization at C-4' through an unusual procedure involving a completely stereospecific hydroboration-oxidation of the enol ether group of the hex-4-enopyranoside 4, obtained from 3 by base promoted acetone elimination, (b) an amination with inversion by S(N)2 reaction on an imidazylate intermediate, and, finally, (c) N-acetylation followed by complete deprotection.
authors.affiliation: Dipartimento di Farmacia, Università di Pisa, via Bonanno 33, I-56126 Pisa, Italy.
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Guazzelli
authors.affiliation: Dipartimento di Farmacia, Università di Pisa, via Bonanno 33, I-56126 Pisa, Italy.
authors.forename: Giorgio
authors.initials: G
authors.lastname: Catelani
authors.affiliation: Dipartimento di Farmacia, Università di Pisa, via Bonanno 33, I-56126 Pisa, Italy. Electronic address: felicia.dandrea@farm.unipi.it.
authors.forename: Felicia
authors.initials: F
authors.lastname: D'Andrea
authors.affiliation: Dipartimento di Farmacia, Università di Pisa, via Bonanno 33, I-56126 Pisa, Italy.
authors.forename: Tiziana
authors.initials: T
authors.lastname: Gragnani
mesh_terms: D000107:Acetylation; D000117:Acetylglucosamine / Q000737:chemistry*; D002240:Carbohydrate Sequence; D004187:Disaccharides / Q000138:chemical synthesis*; D006027:Glycosides / Q000737:chemistry*; D006031:Glycosylation; D007785:Lactose / Q000737:chemistry*; D008969:Molecular Sequence Data; D013237:Stereoisomerism
chemical_list: D004187:Disaccharides; D006027:Glycosides; D007785:Lactose; D000117:Acetylglucosamine
keywords: Amination with inversion; Epimerization; Lactose; β-d-GlcNAc-(1→4)-d-Glc disaccharide