Ring-Opening Polymerization of a 1,4-Anhydro Xylose Derivative Having an Azido Group and Synthesis of Stereoregular 3-Amino-3-deoxy-(1→5)-α- d -xylofuranan
1996; American Chemical Society; Volume: 29; Issue: 9 Linguagem: Inglês
10.1021/ma951605w
ISSN1520-5835
AutoresTakashi Yoshida, Byongwon Kang, Kazuyuki Hattori, Qing Huang, Toshiyuki Uryu,
Tópico(s)Enzyme Catalysis and Immobilization
ResumoA new 1,4-anhydro pentose monomer having an azido group, 1,4-anhydro-3-azido-2-O-benzyl-3-deoxy-α-d-xylopyranose (A3ABX), was synthesized by benzylation of 1,4-anhydro-α-d-ribopyranose at the C2 hydroxyl group and subsequent trifluoromethylsulfonylation at the C3 hydroxyl group, followed by SN2 replacement of the trifluoromethylsulfonyl group with the azido group with lithium azide. Ring-opening polymerization of A3ABX was attempted with Lewis acid catalysts such as boron trifluoride etherate, phosphorus pentafluoride, and antimony pentachloride at different temperatures between −60 and −20 °C. Boron trifluoride etherate catalyst gave a polymer with a positive specific rotation and with a single C1 absorption at 99 ppm in the 13C NMR spectrum, indicating that the resulting polymer had a stereoregular 1,5-α furanosidic structure. When the polymerization was carried out by antimony pentachloride at −60 °C, the polymer obtained had a negative specific rotation and the C1 absorption shifted downfield to around 107 ppm, suggesting that the polymer might be composed of a 1,5-β furanosidic unit. Reduction of the azido group to an amino group and the benzyl group to a hydroxyl group gave 3-amino-3-deoxy-(1→5)-α-d-xylofuranan. The structural analysis of the polysaccharides was performed by means of high-resolution 1H and 13C NMR spectroscopies including the two-dimensional spectra of H−H COSY, NOESY, and FGHMQC.
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