Intramolecular 1,8-Hydrogen Atom Transfer Reactions in Disaccharide Systems Containing Furanose Units
作者:Sabrina Guyenne、Elisa I. León、Angeles Martín、Inés Pérez-Martín、Ernesto Suárez
DOI:10.1021/jo301153u
日期:2012.9.7
A previously developed 1,8-hydrogen atom transfer (HAT) reaction promoted by 6-O-yl alkoxyl radicals between the two pyranose units in Hexp-(1→4)-Hexp disaccharides has been extended to other systems containing at least a furanose ring in their structures. In Penf-(1→3)-Penf (A) and Hexp-(1→3)-Penf (B) disaccharides, the 1,8-HAT reaction and concomitant cyclization to a 1,3,5-trioxocane ring are in
以前开发的由Hex p-(1→4)-Hex p二糖中两个吡喃糖单元之间的6- O-烷基烷氧基所促进的1,8-氢原子转移(HAT)反应已扩展到至少包含至少在其结构中有呋喃糖环。在Pen f-(1→3)-Pen f(A)和Hex p-(1→3)-Pen f(B)二糖,1,8-HAT反应和伴随的环化成1,3,5-三氧杂环丁烷环与C4–C5键的自由基β断裂和脱同源产物的形成竞争。使用四种可能的d-呋喃糖酶异构体研究了立体电子β-氧效应对β-断裂的影响,进而对1,8-HAT反应的影响。d -木糖-和d -来苏-衍生物给予优先1,8-HAT产品,而d -阿拉伯-和d -核糖-衍生物给烃氧基专门直接β-断裂。当6- O如在Pen f-(1→4)-Hex p(C)中所出现的,吡喃糖基团在吡喃糖环上显示出仅提供环化产物。