Temperature and solvent dependent NMR studies on mangiferin and complete NMR spectral assignments of its acyl and methyl derivatives
作者:Shaheen Faizi、Sadia Zikr-ur-Rehman、Muhammad Ali、Aneela Naz
DOI:10.1002/mrc.1854
日期:2006.9
employing concerted 1 and 2D NMR techniques, exact NMR spectral assignments have been made of the acyl (2–7) and methyl (8 and 9) derivatives of mangiferin (1) isolated from the leaves of Bombax ceiba. Derivatives 2, 8 and 9 have been reported in literature, while 3–7 represent new compounds. The acetates 2 and 3 were found to be unstable and were converted into the same penta‐acetate 4 at room temperature
通过采用协调一致的 1 维和 2D NMR 技术,已经对从木棉叶中分离的芒果苷 (1) 的酰基 (2-7) 和甲基 (8 和 9) 衍生物进行了精确的 NMR 光谱分配。衍生物 2、8 和 9 已在文献中报道,而 3-7 代表新化合物。发现醋酸盐 2 和 3 不稳定,在室温下会转化为相同的五醋酸盐 4。对芒果苷 (1) 及其衍生物的广泛 NMR 研究表明,H-4 更容易与溶剂分子的氘交换。这种在酸性条件下的交换发生在容易发生亲电取代反应的位置 (C-4)。这是描述芒果苷 (1) 或任何其他氧杂蒽酮的 C-4 质子与溶剂分子的氘交换的第一份报告。