Reductive Elimination from Phosphine-Ligated Alkylpalladium(II) Amido Complexes To Form sp3 Carbon-Nitrogen Bonds.
Reductive Elimination from Phosphine-Ligated Alkylpalladium(II) Amido Complexes To Form sp3 Carbon-Nitrogen Bonds.
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膦连接的烷基钯 (II) 氨基配合物的还原消除形成 sp3 碳-氮键。
DOI：
10.1021/jacs.8b00928
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发表时间：
2018
影响因子：
15
通讯作者：
Hartwig,JohnF
中科院分区：
文献类型：
--
作者：
Peacock,DMatthew;Jiang,Quan;Hanley,PatrickS;Cundari,ThomasR;Hartwig,JohnF
我们报道了膦连接的烷基钯(II)酰胺络合物的形成，这些络合物经过还原消除形成烷基-氮键，并对控制这些反应速度的因素进行了联合实验和计算研究。T-Bu3P连接的络合物的还原消除自由能垒显著低于以前报道的NHC连接的络合物的还原消除自由能垒(约3kcal/mol)。含有一系列电子和空间位置不同的苯胺基配体的络合物的反应速度表明，对于电子丰度较低或空间位阻较高的苯胺基配体的络合物，还原消除速度慢于那些含有较多电子和较少阻碍的苯胺基配体的络合物。含双齿P，O配体的络合物也发生了烷基胺的还原消除。四配位络合物的反应速度慢于三配位的t-Bu3P-配体络合物的反应速度。计算的从刚性的，2-甲氧基芳基膦连接的络合物中还原消除的途径不涉及氧的初始解离。相反，还原消除被计算为直接从四配位络合物发生，与Pd-O键的延长一致。为了从实验上研究这一效应，合成了一种四配位的Pd(II)-苯胺基配合物，该配合物的P原子和O原子之间含有一个柔性的脂肪族连接物。从该络合物中的还原消除比从含有更刚性的芳基接头的类似络合物中的还原消除更快。柔性连接体能够在还原消除过程中使乙醚配体完全解离，导致该络合物的反应速度更快。
We report the formation of phosphine-ligated alkylpalladium(II) amido complexes that undergo reductive elimination to form alkyl-nitrogen bonds and a combined experimental and computational investigation of the factors controlling the rates of these reactions. The free-energy barriers to reductive elimination fromt-Bu3P-ligated complexes were significantly lower (ca. 3 kcal/mol) than those previously reported from NHC-ligated complexes. The rates of reactions from complexes containing a series of electronically and sterically varied anilido ligands showed that the reductive elimination is slower from complexes of less electron-rich or more sterically hindered anilido ligands than from those containing more electron-rich and less hindered anilido ligands. Reductive elimination of alkylamines also occurred from complexes bearing bidentate P,O ligands. The rates of reactions of these four-coordinate complexes were slower than those for reactions of the three-coordinate,t-Bu3P-ligated complexes. The calculated pathway for reductive elimination from rigid, 2-methoxyarylphosphine-ligated complexes does not involve initial dissociation of the oxygen. Instead, reductive elimination is calculated to occur directly from the four-coordinate complex in concert with a lengthening of the Pd–O bond. To investigate this effect experimentally, a four-coordinate Pd(II) anilido complex containing a flexible, aliphatic linker between the P and O atoms was synthesized. Reductive elimination from this complex was faster than that from the analogous complex containing the more rigid, aryl linker. The flexible linker enables full dissociation of the ether ligand during reductive elimination, leading to the faster reaction of this complex.
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DOI：
--
发表时间：
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期刊：
Ophthalmology (Rochester, Minn.)
影响因子：
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DOI：
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