Mechanism and Selectivity of Aryltrimethylgermane Cation Radical Fragmentations
Mechanism and Selectivity of Aryltrimethylgermane Cation Radical Fragmentations
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芳基三甲基锗烷阳离子自由基断裂的机理和选择性
DOI：
10.1021/acs.joc.0c01032
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发表时间：
2020
期刊：
影响因子：
--
通讯作者：
Dinnocenzo, Joseph P.
中科院分区：
文献类型：
--
作者：
Feinberg, Adam M.;Dinnocenzo, Joseph P.
通过纳秒瞬态吸收光谱产生芳基三甲基锗烷阳离子自由基。瞬态动力学实验表明，芳基三甲基锗烷阳离子自由基与添加的亲核试剂发生反应，该反应在阳离子自由基和亲核试剂中都是一级反应。制备型光氧化实验表明，中间体阳离子自由基与亲核试剂发生反应，产生芳基-Ge 或 Me-Ge 亲核试剂辅助的断裂。发现芳基三甲基锗烷阳离子自由基比类似的锡烷阳离子自由基反应更慢；然而，热力学不利的芳基自由基的损失仍然与甲基自由基的损失竞争。
Aryltrimethylgermane cation radicals were generated by nanosecond transient absorption spectroscopy. Transient kinetics experiments show that the aryltrimethylgermane cation radicals react with added nucleophiles in reactions that are first-order in both the cation radicals and the nucleophiles. Preparative photo-oxidation experiments demonstrate that the intermediate cation radicals react with nucleophiles, resulting in aryl–Ge or Me–Ge nucleophile-assisted fragmentations. The aryltrimethylgermane cation radicals were found to react more slowly than analogous stannane cation radicals; however, loss of the thermodynamically disfavored aryl radicals remains competitive with methyl radical loss.