reported. The NMR spectra show that the two δ-dicarbonyl sugars exist as two anomeric α- and β-oxetanosyl forms, derived from the hemiacetalization of the C-3 hydroxyl group with the aldehydic carbon. The observed tautomeric equilibria have been rationalized with computational calculations. Interestingly, this is the first time that dicarbonyl derivatives are mostly present in their oxetanose forms, offering
据报道,从4-deoxyhex-4-enopyranosides开始合成4-deoxy-和4-deoxy-4- C -methylhexos-5-uloses,并对其核磁共振异构体组成进行了核磁共振(NMR)研究。NMR光谱显示,两种δ-二羰基糖以两种异头异构体α-和β-氧杂环糖基形式存在,其衍生自C-3羟基与醛碳的
半缩醛化。观察到的互变异构平衡已通过计算计算合理化。有趣的是,这是二羰基衍
生物首次以其氧杂
环丁烷形式存在,这为这种非常有趣的支架类型提供了新的契机。