Intramolecular Hydrogen Abstraction Reaction Promoted by Alkoxy Radicals in Carbohydrates. Synthesis of Chiral 2,7-Dioxabicyclo[2.2.1]heptane and 6,8-Dioxabicyclo[3.2.1]octane Ring Systems
作者:Cosme G. Francisco、Antonio J. Herrera、Ernesto Suárez
DOI:10.1021/jo026004z
日期:2002.10.1
for the synthesis of chiral 6,8-dioxabicyclo[3.2.1]octane and 2,7-dioxabicyclo[2.2.1]heptane ring systems under neutral conditions. This reaction can be considered to be an intramolecular glycosidation that goes through an intramolecular hydrogen abstraction promoted by an alkoxy radical followed by oxidation of the transient C-radical intermediate to an oxycarbenium ion. This methodology is useful
特定保护的脱水醛糖醇与(二乙酰氧基碘)苯或碘基苯与碘的反应是合成手性6,8-二氧杂双环[3.2.1]辛烷和2,7-二氧杂双环[2.2.1]庚烷环的温和选择性步骤系统在中性条件下。该反应可被认为是分子内糖苷化,其经历由烷氧基自由基促进的分子内氢提取,然后将瞬时的C-自由基中间体氧化成氧碳鎓离子。该方法不仅可用于手性合成子的制备,而且可用于碳水化合物骨架的特定碳的选择性氧化,这是合成被保护的果糖的良好方法。