H. Takeda, Toru Kaiya, N. Yasuoka
Apr 1, 1978
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Influential Citations
14
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Journal
Carbohydrate Research
Abstract
Abstract The crystal and molecular structure of methyl 2,3,4,6,2′,4′,6′-hepta- O -acetyl β-laminarabioside has been determined by X-ray diffraction. The crystal belongs to the orthorhombic system space group P2 1 2 1 2 1 , a 10.471 (1), b 22.482(1), c 13.647(1) A, D m 1.33 g.cm −3 , Z 4 . The structure was established by the direct method and refined by the block-diagonal, least-squares procedure to R 0.093 for 2043 observed reflections. Difference synthesis showed all the hydrogen atoms except the methyl hydrogen ones. The molecule shows a fully-extended conformation and has no intra-molecular hydrogen bond. The ring-to-ring conformation can be described.as (φψ) (42.5, 4.7°), according to the definition of Sathyanarayana and Rao, and it is compared with (φψ) (27.9, −37.5°) of laminarabiose. There is no inter-molecular hydrogen bond. The d -glucopyranose rings of the molecule are piled up along the a axis and approximately parallel to the bc -plane. Each of the acetyl groups is approximately perpendicular to the d -glucopyranose ring.