Crystal packing in three related disaccharides: precursors to heparan sulfate oligosaccharides

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 mol­ecule in the asymmetric unit. Two of them are isostructural: 4-meth­oxy­phenyl 4-O-[6-O-acetyl-2-azido-3-O-benzyl-2-de­oxy-4-O-(9-fluor­en­yl­methyl­oxycarbon­yl)-α-d-gluco­pyranos­yl]-2-O-benzoyl-3-O-benzyl-6-O-chloro­acetyl-α-l-ido­pyran­oside, C(59)H(56)ClN(3)O(16), (I), the ido-relative of a reported gluco-disaccharide [Gainsford et al., 2013 ▸). Acta Cryst. C69, 679–682] and 4-meth­oxy­phenyl 4-O-[6-O-acetyl-2-azido-3-O-benzyl-2-de­oxy-4-O-(9-fluorenyl­methyl­oxycarbon­yl)-α-d-gluco­pyranos­yl]-2-O-benzoyl-3-O-benzyl-6-O-meth­oxy­acetyl-α-l-ido­pyran­oside, C(60)H(59)N(3)O(17), (II). Both exhibit similar conformational disorder of pendant groups. The third compound 4-meth­oxy­phenyl 4-O-[6-O-acetyl-2-azido-3,4-di-O-benzyl-2-de­oxy-α-d-gluco­pyranos­yl]-2-O-benzoyl-3-O-benzyl-6-O-meth­oxy­oacetyl-β-d-gluco­pyran­oside, C(52)H(55)N(3)O(15), (III), illustrates that a slightly larger set of weak inter­molecular inter­actions can result in a less disordered mol­ecular arrangement. The mol­ecules are bound by weak C—H⋯O(ether) hydrogen bonds in (I) and (II), augmented by C—H⋯π inter­actions in (III). The absolute configurations were determined, although at varying levels of significance from the limited observed data.