Microwave-assisted generation of alkoxyl radicals and their use in additions, β-fragmentations, and remote functionalizations
作者:Jens Hartung、Kristina Daniel、Thomas Gottwald、Andreas Groß、Nina Schneiders
DOI:10.1039/b603480b
日期:——
solvents affords alkoxyl radicals, which were identified by (i) spin adduct formation (EPR-spectroscopy) and (ii) fingerprint-type selectivities in intramolecular additions (stereoselective synthesis of disubstituted tetrahydrofurans), beta-fragmentations (formation of carbonyl compounds), and C,H-activation of aliphatic subunits, by delta-selective hydrogen atom transfer. C-Radicals formed from oxygen-centered
N-(烷氧基)噻唑-2(3H)-硫酮在低吸收性溶剂中的微波辐射(2.45 GHz,300-500 W)提供烷氧基,其通过以下方法鉴定:(i)自旋加合物形成(EPR光谱)和(ii)通过δ-选择性氢原子转移在分子内加成(二取代的四氢呋喃的立体选择性合成),β-片段化(羰基化合物的形成)和脂族亚基的C,H-活化中的指纹类型选择性。由以氧为中心的中间体形成的C自由基被Bu(3)SnH,L-半胱氨酸乙酯,谷胱甘肽的还原形式(还原性俘获)捕获,或通过溴原子供体BrCCl(3)(杂原子功能化)进行研究结果表明,微波活化优于UV / Vis光解法和传导加热,可从N-(烷氧基)噻唑硫酮生成烷氧基自由基。到目前为止,它提供了最短的反应时间,并且可以显着减少捕集试剂的量。