title: Crystal packing in three related disaccharides: precursors to heparan sulfate oligosaccharides.
abstract: The three title compounds form part of a set of important precursor dissacharides which lead to novel therapeutics, in particular for Alzheimer's disease. All three crystallize as poorly diffracting crystals with one independent mol-ecule in the asymmetric unit. Two of them are isostructural: 4-meth-oxy-phenyl 4-O-[6-O-acetyl-2-azido-3-O-benzyl-2-de-oxy-4-O-(9-fluor-en-yl-methyl-oxycarbon-yl)-α-d-gluco-pyranos-yl]-2-O-benzoyl-3-O-benzyl-6-O-chloro-acetyl-α-l-ido-pyran-oside, C59H56ClN3O16, (I), the ido-relative of a reported gluco-disaccharide [Gainsford et al., 2013 ▶). Acta Cryst. C69, 679-682] and 4-meth-oxy-phenyl 4-O-[6-O-acetyl-2-azido-3-O-benzyl-2-de-oxy-4-O-(9-fluorenyl-methyl-oxycarbon-yl)-α-d-gluco-pyranos-yl]-2-O-benzoyl-3-O-benzyl-6-O-meth-oxy-acetyl-α-l-ido-pyran-oside, C60H59N3O17, (II). Both exhibit similar conformational disorder of pendant groups. The third compound 4-meth-oxy-phenyl 4-O-[6-O-acetyl-2-azido-3,4-di-O-benzyl-2-de-oxy-α-d-gluco-pyranos-yl]-2-O-benzoyl-3-O-benzyl-6-O-meth-oxy-oacetyl-β-d-gluco-pyran-oside, C52H55N3O15, (III), illustrates that a slightly larger set of weak inter-molecular inter-actions can result in a less disordered mol-ecular arrangement. The mol-ecules are bound by weak C-H⋯O(ether) hydrogen bonds in (I) and (II), augmented by C-H⋯π inter-actions in (III). The absolute configurations were determined, although at varying levels of significance from the limited observed data.
authors.affiliation: CallaghanInnovation, PO Box 31-310, Lower Hutt 5040, New Zealand.
authors.forename: Graeme J
authors.initials: GJ
authors.lastname: Gainsford
authors.affiliation: Ferrier Research Institute, Victoria University of Wellington, PO Box 33 436, Petone, Lower Hutt 5046, New Zealand.
authors.forename: Ralf
authors.initials: R
authors.lastname: Schwörer
authors.affiliation: Ferrier Research Institute, Victoria University of Wellington, PO Box 33 436, Petone, Lower Hutt 5046, New Zealand.
authors.forename: Peter C
authors.initials: PC
authors.lastname: Tyler
authors.affiliation: Ferrier Research Institute, Victoria University of Wellington, PO Box 33 436, Petone, Lower Hutt 5046, New Zealand.
authors.forename: Olga V
authors.initials: OV
authors.lastname: Zubkova
keywords: Alzheimer’s; C—H⋯π contacts; crystal structure; disaccharide; hydrogen bonding; synthesis