Reaction of hydrogen bromide in glacial acetic acid upon 3, 4, 6-tri-O-acetyl-D-glucal and successive treatment of the reaction product with aqueous acetone under the presence of silver carbonate afforded crystals (V), mp 99°, [α]
20D+40.5°→+34.5°, in 70% yield. The product was also obtainable from 2, 3-dideoxy-1, 4, 6-tri-O-acetyl-D-erythro-hex-2-enose or 2-deoxy-1, 3, 4, 6-tetra-O-acetyl-α-D-arabino-hexopyranose in 70 or 50% yield. The structure of V was assigned to 3-bromo-4, 6-di-O-acetyl-2, 3-dideoxy-α-arabino-hexo-pyranose. Acetylation of V with acetic anhydride in pyridine gave crystals (VI), mp 82°, [α]
20D+58°, in 85% yield. The structure of VI was assigned to 3-bromo-2, 3-dideoxy-1, 4, 6-tri-O-acetyl-α-D-arabino-hexopyranose. The physical constants of V and VI were in agreement with that of the Fischer's Glucal-hydrobromid-diacetat and triacetat (E. Fischer, M. Berg-mann, and H. Schotte, Ber., 53, 509 (1920)), which might presumably be the same compounds.
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