On the Mechanism and Kinetics of Radical Reactions of Epoxyketones and Epoxynitriles Induced by Titanocene Chloride
作者:A. Fernández-Mateos、P. Herrero Teijón、L. Mateos Burón、R. Rabanedo Clemente、R. Rubio González
DOI:10.1021/jo701497e
日期:2007.12.1
γ-epoxynitriles with Ti(III) corresponds to a radical reaction (k25 ≈ 106 s-1), as demonstrated by competition experiments with H-transfer from 1,4-cyclohexadiene (1,4-CHD) or PhSH or conjugate addition to acrylonitrile. The 5-exo cyclization onto nitrile induced by Ti(III) is a radical reaction (k25 ≈ 107 s-1) as seen in competition experiments with H-transfer from PhSH or the titanocene−water complex. The iminyl
研究了由钛茂氯化物诱导的一系列环氧腈和环氧酮的反应。β,γ-epoxynitriles与钛(III)对应的decyanogenation的这样的基团反应(动力学ķ 2 5 ≈10 6个小号- 1,这表现在竞争实验与由1,4-环己二烯H-传递(1) ,4-CHD)或PhSH或共轭加成到丙烯腈中。5-外型环化到由钛(III)诱导的腈是自由基反应(ķ 2 5 ≈10 7个小号- 1),如在从PhSH或钛茂-水络合物进行H转移的竞争实验中看到的。通过5- exo环化到腈或酮上生成的亚胺基或烷氧基仅经过Ti(III)还原。该反应使任何其他方法不堪重负,例如串联环化成烯烃或β-分裂。当α-取代基为CN时,通过4- exo环化作用到腈上的亚氨基自由基经过Ti(III)和β-断裂反应以96:4的比例还原。来自4- exo的烷氧基当α-取代基为COOR时,酮羰基上的环化反应会以Ti(III)和β-断裂的比例