β-Fragmentation of Primary Alkoxyl Radicals versus Hydrogen Abstraction: Synthesis of Polyols and α,ω-Differently Substituted Cyclic Ethers from Carbohydrates
作者:Alicia Boto、Dácil Hernández、Rosendo Hernández、Ernesto Suárez
DOI:10.1021/jo034442f
日期:2003.6.1
The beta-fragmentation of primary alkoxyl radicals, described in many cases as low-yielding and plagued by side reactions, can proceed in satisfactory yields using carbohydrate substrates. The only reaction that can compete significantly with the beta-scission is the intramolecular hydrogen abstraction. The ratio of beta-fragmentation to hydrogen abstraction can be varied according to the reaction conditions
在许多情况下被描述为低产率且受副反应困扰的伯烷氧基自由基的β片段化,可以使用碳水化合物底物以令人满意的收率进行。唯一可以与β-分裂竞争的反应是分子内氢的夺取。可以根据反应条件,取代基(例如,α-或β-异头异构体取代基)的立体化学以及所选择的保护基来改变β-片段化与氢提取的比例。碳水化合物底物易于制备,温和的反应条件与大多数官能团相容。β-断裂反应为更短和更不常见的糖系列以及向α,ω-不同取代的环状醚提供了一种简便的方法。