Mechanism and Unusual Fragmentation Selectivities of Aryltrialkylstannane Cation Radicals
作者:Pu Luo、Joseph P. Dinnocenzo
DOI:10.1021/acs.joc.5b01690
日期:2015.9.18
Aryltrialkylstannane cation radicals were generated and characterized by nanosecond transient absorption spectroscopy. Kinetics show the fragmentations of the stannane cation radicals occur by a bimolecular, nucleophile-assisted mechanism (SN2). Consistent with this hypothesis, steric effects on both the nucleophile and the stannane cation radicals were observed. Steady-state, preparative photooxidation
产生了芳基三烷基锡烷阳离子自由基,并通过纳秒瞬态吸收光谱对其进行了表征。动力学表明,锡烷阳离子自由基的断裂是通过双分子亲核试剂辅助机制(S N 2)发生的。与该假设一致,观察到了对亲核试剂和锡烷阳离子自由基的空间位阻。稳态的制备性光氧化实验表明,芳基三甲基锡烷阳离子自由基对芳基自由基的损失优于甲基自由基,并且芳基对甲基自由基损失的选择性取决于亲核试剂的身份。通过基于Bent规则的假设合理化了对芳基自由基损失的偏爱。