An appraisal of oxoketene cycloaddition methodology for the synthesis of 2,6-dideoxysugars and fluorinated 2,6-dideoxysugars
作者:Christophe Audouard、Kim Bettaney (née Middleton)、Châu T. Doan、Giuseppe Rinaudo、Peter J. Jervis、Jonathan M. Percy
DOI:10.1039/b817672h
日期:——
The cycloaddition reaction of acylketenes with vinyl ethers affords an extremely direct route to 2,6-dideoxysugars and their methyl ethers. The lithium enolate of commercial 2,6,6-trimethyldioxinone 3 was fluorinated in good yield to afford fluorinated dioxinone 8. An illustrative range of fluorinated 2,6-dideoxysugar derivatives was prepared via the acetyl ketene–vinyl ether cycloadduct. Electronic
酰基乙烯酮与乙烯基醚的环加成反应提供了一条直接的途径来制备2,6-二脱氧糖及其甲基醚。商业化的2,6,6-三甲基二恶英酮3的烯醇锂以良好的产率被氟化,得到氟化的二恶英酮8。通过乙酰基乙烯酮-乙烯基醚环加合物制备了一系列示例性的氟化2,6-二脱氧糖衍生物。进行电子结构计算以研究氟原子对(氟乙酰基)乙烯酮反应性中间体的易于形成和随后反应的影响。单个氟原子可降低约25%的片段化势垒。7.5 kJ摩尔-1,与实验结果一致,但对确定乙烯基醚添加速率或氧杂环丁烯二聚化的障碍几乎没有影响。