Theoretical prediction of Ni(I)‐catalyst for hydrosilylation of pyridine and quinoline
Theoretical prediction of Ni(I)‐catalyst for hydrosilylation of pyridine and quinoline
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DOI：
10.1002/jcc.25864
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发表时间：
2019-09
影响因子：
3
通讯作者：
Vijay P Singh;S. Sakaki;M. Deshmukh
中科院分区：
文献类型：
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作者：
Vijay P Singh;S. Sakaki;M. Deshmukh
过渡金属配合物催化合成二氢吡啶是近年来的重要研究目标之一。密度泛函理论计算表明，氢化镍 (I) 配合物 (bpy)NiIH (bpy = 2,2′-联吡啶) 1 是喹啉和吡啶氢化硅烷化的良好催化剂。有两种可能的途径：在路径1中，底物与1反应形成稳定的中间体Int1。之后，底物的N3─C1键通过TS1插入1的Ni─H键中，得到N配位的1,2-二氢喹啉Int2，其吉布斯活化能(ΔG°‡)为21.8 kcal mol−1。然后，Int2与氢硅烷反应形成氢硅烷σ配合物Int3；这被命名为路径 1A。在另一条路线（路径1B）中，Int1通过氢化物穿梭过渡态TS2与苯基硅烷以协调的方式反应，得到Int3。 TS2中，Si原子呈高价三角双锥结构。超价结构的形成对于 TS2 的稳定至关重要（ΔG°‡ = 17.3 kcal mol−1）。路径1的最后一步是Int3的Ni─N3键和PhSiH3的Si─H键之间的复分解，得到N-甲硅烷基化的1,2-二氢产物并再生1（ΔG°‡ = 4.5 kcal mol−1）。在路径2中，1与氢硅烷反应形成Int5，然后通过底物和PhSiH3之间的Si-N相互作用与底物形成加合物Int6。然后，通过氢化物穿梭过渡态 TS5（ΔG°‡ = 18.8 kcal mol−1）生成 N-甲硅烷基化 1,2-二氢产物。 TS5 中底物与 NiI 缺乏 N 配位是路径 2 不如路径 1B 有利的原因。喹啉氢化硅烷化比吡啶更容易发生，因为喹啉在比吡啶低的能量下具有最低的未占据分子轨道。 © 2019 Wiley 期刊公司。
Catalytic synthesis of dihydropyridine by transition‐metal complex is one of the important research targets, recently. Density functional theory calculations here demonstrate that nickel(I) hydride complex (bpy)NiIH (bpy = 2,2′‐bipyridine) 1 is a good catalyst for hydrosilylation of both quinoline and pyridine. Two pathways are possible; in path 1, substrate reacts with 1 to form stable intermediate Int1. After that, N3─C1 bond of substrate inserts into Ni─H bond of 1 via TS1 to afford N‐coordinated 1,2‐dihydroquinoline Int2 with the Gibbs activation energy (ΔG°‡) of 21.8 kcal mol−1. Then, Int2 reacts with hydrosilane to form hydrosilane σ‐complex Int3; this is named path 1A. In the other route (path 1B), Int1 reacts with phenylsilane in a concerted manner via hydride‐shuttle transition state TS2 to afford Int3. In TS2, Si atom takes hypervalent trigonal bipyramidal structure. Formation of hypervalent structure is crucial for stabilization of TS2 (ΔG°‡ = 17.3 kcal mol−1). The final step of path 1 is metathesis between Ni─N3 bond of Int3 and Si─H bond of PhSiH3 to afford N‐silylated 1,2‐dihydroproduct and regenerate 1 (ΔG°‡ = 4.5 kcal mol−1). In path 2, 1 reacts with hydrosilane to form Int5, which then forms adduct Int6 with substrate through Si–N interaction between substrate and PhSiH3. Then, N‐silylated 1,2‐dihydroproduct is produced via hydride‐shuttle transition state TS5 (ΔG°‡ = 18.8 kcal mol−1). The absence of N‐coordination of substrate to NiI in TS5 is the reason why path 2 is less favorable than path 1B. Quinoline hydrosilylation occurs more easily than pyridine because quinoline has the lowest unoccupied molecular orbital at lower energy than that of pyridine. © 2019 Wiley Periodicals, Inc.