T. Conturo, G. A. Jeffrey
Jun 1, 1982
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Carbohydrate Research
Abstract
Abstract The crystal structure of methyl 4,6-O-benzylidene-2,3-dideoxy-2-[2-(methoxycarbonyl)phenylamino]-3-nitro-β- d -mannopyranoside, C22H24N2O8, is monoclinic, P21, with cell dimensions a = 13.267(4), b = 9.633(4), c = 8.839(3) A, β = 106.26(2)°, Z = 2. The structure was solved by direct methods, and refined to R(Fobs) = 0.056 for 6959 independent reflections measured with MoKα radiation. The configuration of the molecule was confirmed. The pyranoid conformation is 4C1 with Q = 0.611 A, = 8.5°. The dioxolane conformation is close to the ideal chair. The orientation of the anthranilate ring is such that the amine hydrogen atom forms three intramolecular hydrogen-bonds: one major bond to the anthranilate carbonyl oxygen atom, and two minor bonds to the glycosidic oxygen atom and the ring-oxygen atom. The orientation of the anthranilate group is thus fixed such that the angle between the plane of the benzene ring and that of the nitro group is 116°, thereby permitting an intramolecular, CHO hydrogen-bond between the benzene ortho CH and the nitro oxygen atom. This bond is normal to the plane of the nitro group, and is believed to be the source of the color phenomenon that prompted this structure analysis.