Synthesis of tri-, penta-, and heptasaccharides, functionalized with orthogonally N-protected amino residues at the reducing and non-reducing ends

• Published in: Tetrahedron 2012-08, Vol.68 (33), p.6712-6720
• Main Authors: Fyrner, Timmy, Svensson, Stefan C.T., Konradsson, Peter
• Format: Article
• Language: English
• Subjects: Bifunctionalized; Carbohydrates; Carbohydrates with 4, 5, 6, ... C atoms, dissacharides and oligosaccharides; Carbohydrates. Nucleosides and nucleotides; Chemistry; Exact sciences and technology; Glycosidation; Glycosylation; Oligosaccharide synthesis; Organic chemistry; Orthogonally protected; Preparations and properties; Spacer molecules
• ISSN: 0040-4020; 1464-5416
• DOI: 10.1016/j.tet.2012.05.118

The synthesis of four bifunctionalized orthogonally N-protected oligosaccharides derived from lactose and mannose, intended as cross-linking derivatives, is described. The aminosugar at the non-reducing end is derivatized with an N-Boc-protected glycine moiety, and further connected to either a mannose (1→6) disaccharide or (1→3) lactose units (one, two or three) resulting in tri-, penta-, or heptasaccharides. All of the synthesized oligosaccharides have an N-benzyloxycarbonyl-aminoethyl residue at the reducing end. The orthogonal N-Boc/N-Cbz protection group pattern enables further conjugation/derivatization and results in a hydrophilic cross-linking molecule. It was found that the order of the final synthetic steps was crucial to avoid acyl migration. A suitable amide coupling protocol has been applied to introduce the N-Boc-protected glycine moiety in alcoholic solvent. The synthesized oligosaccharides will provide a model system to investigate the influence of length, structure and flexibility. [Display omitted]