Beneficial Effect of Internal Hydrogen Bonding Interactions on the β-Fragmentation of Primary Alkoxyl Radicals. Two-Step Conversion of <scp>d</scp>-Xylo- and <scp>d</scp>-Ribofuranoses into <scp>l</scp>-Threose and <scp>d</scp>-Erythrose, Respectively
作者:Luís Hernández-García、Leticia Quintero、Mario Sánchez、Fernando Sartillo-Piscil
DOI:10.1021/jo0709551
日期:2007.10.1
N-phthalimido derivatives under reductive conditions. Primary alkoxyl radicals derived from their corresponding xylo- and ribofuranose derivatives underwent, exclusively, an unusual β-fragmentation affording l-threose and d-erythrose derivatives, respectively. This occurs because the alkoxyl radical is capable of achieving an internal hydrogen-bonding interaction leading to a stable six-membered ring intramolecular
伯烷氧基自由基是在还原条件下由其易于合成的N-邻苯二甲酰亚胺基衍生物生成的。衍生自其相应的木糖和呋喃呋喃糖衍生物的伯烷氧基自由基仅经历异常的β片段化,分别得到1-苏糖和d-赤藓糖衍生物。发生这种情况是因为烷氧基能够实现内部氢键相互作用,从而导致稳定的六元环分子内氢键结构。当羟基被保护时,阻止了β-片段化途径,并且发生了氢原子转移(HAT)途径。计算研究为实验观察提供了有力的支持。