Radical Reductive Elimination from Tetrabenzyluranium Mediated by an Iminoquinone Ligand
Radical Reductive Elimination from Tetrabenzyluranium Mediated by an Iminoquinone Ligand
复制标题
亚氨基醌配体介导的四苄基铀的自由基还原消除
DOI：
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发表时间：
2014
期刊：
影响因子：
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通讯作者：
Suzanne C. Bart
中科院分区：
文献类型：
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作者：
E. Matson;Sebastian M. Franke;Nickolas H. Anderson;Timothy D. Cook;P. Fanwick;Suzanne C. Bart
观察到4，6-二叔丁基-2-[（2，6-二异丙基苯基）亚氨基]醌（dippiq）介导的U（CH 2 Ph）4（1-Ph）的还原消除，导致形成（dippap）2U（CH 2 Ph）2（THF）2（2）（dippap = 4，6-二叔丁基-2-[（2，6-二异丙基苯基）氨基]苯酚盐）和联苄基。与U（CD 2C 6D 5）4的交叉实验表明形成bibenzyl-d 7，表明还原消除发生在一个逐步的方式通过苄基自由基挤出，推测通过亚氨基半醌三（苄基）中间体，（dippisq）U（CH 2 Ph）3。尝试通过将亚氨基醌配体添加到UI 3（THF）4中以形成（dippisq）UI 3（3），然后用3当量的苄基钾进行烷基化来合成该中间体。然而，这仅导致2的分离。用KC 8还原3得到氨基苯酚二碘化物（dippap）UI 2（THF）2（4），保持铀的四价氧化态并还原配体。在形成2通过添加2当量的苄基钾T的尝试。
Reductive elimination from U(CH2Ph)4 (1-Ph) mediated by 4,6-di-tert-butyl-2-[(2,6-diisopropylphenyl)imino]quinone (dippiq) was observed, resulting in the formation of (dippap)2U(CH2Ph)2(THF)2 (2) (dippap = 4,6-di-tert-butyl-2-[(2,6-diisopropylphenyl)amido]phenolate) and bibenzyl. The crossover experiment with U(CD2C6D5)4 showed formation of bibenzyl-d7, indicating that reductive elimination occurs in a stepwise fashion via benzyl radical extrusion, presumably through an iminosemiquinone tris(benzyl) intermediate, (dippisq)U(CH2Ph)3. Synthesis of this intermediate was attempted by addition of the iminoquinone ligand to UI3(THF)4 to form (dippisq)UI3 (3), followed by alkylation with 3 equiv of benzylpotassium. However, this only resulted in the isolation of 2. Reduction of 3 with KC8 afforded the amidophenolate diiodide species (dippap)UI2(THF)2 (4), maintaining the tetravalent oxidation state of the uranium and reducing the ligand. Attempts at the formation of 2 via addition of 2 equiv of benzylpotassium t...