Mechanism, catalysis and predictions of 1,3,2-diazaphospholenes: theoretical insight into highly polarized P-X bonds
Mechanism, catalysis and predictions of 1,3,2-diazaphospholenes: theoretical insight into highly polarized P-X bonds
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1,3,2-二氮杂磷烯的机理、催化和预测：高度极化 P-X 键的理论见解
DOI：
10.1039/c6qo00002a
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发表时间：
2016
影响因子：
5.4
通讯作者：
Zhao Yufen
中科院分区：
文献类型：
--
作者：
Liu Liu;Wu Yile;Chen Peng;Chan Chinglin;Xu Ji;Zhu Jun;Zhao Yufen
通过密度泛函理论（DFT）计算来研究几种主族氢化物的氢化物特征。杂环骨架上具有两个 π 电子供体氨基的 P-Hydrido-1,3,2-二氮杂磷烯 1f 由于显着的 n(N)–σ*(P–H) 超共轭，可作为强氢化物供体。自然键轨道分析表明，1f 和相应的稳定鏻 Ef+ 中都存在高 π 电子离域。此外，与1e相比，1f对于丙酮与频那醇硼烷的硼氢化反应具有相似的催化能力。因此，我们探索了多种被1f激活的有机底物，包括酮、亚胺、异氰酸酯、CO2、二氮烯、烯烃、炔烃和环氧化物。结果表明，高度极化和缺电子的键如CO π 键很容易被激活，而1f 似乎很难与丙烯和丙炔的富电子不饱和键发生反应。更重要的是，基于 1,3,2-二氮杂磷烯的化合物具有极其极化的 P-X 键（X = CCMe、NMe2、PMe2 和 SMe），预计具有有用的催化能力。初步计算结果表明，这些P-X化合物可以分别催化丙酮与TMSNMe2、TMSPMe2和TMSSMe的甲硅烷基化、甲硅烷基次膦化和甲硅烷基磺基化。产物为甲硅烷基醚，与相应的醇相当，因为它们很容易水解。我们的计算研究为新型主族有机催化剂的设计开辟了一条新途径。
Density functional theory (DFT) calculations were carried out to investigate the hydridic character of several main group hydrides. A P-hydrido-1,3,2-diazaphospholene 1f with two π-electron donor amino groups on the heterocyclic skeleton framework performs as a strong hydride donor owing to the significant n(N)–σ*(P–H) hyperconjugation. The natural bond orbital analysis reveals that high π-electron delocalization exists in both 1f and the corresponding stable phosphenium Ef+. In addition, 1f is calculated to have a similar catalytic ability for the hydroboration of acetone with pinacolborane, compared to 1e. Thus, a variety of organic substrates activated by 1f are explored, including ketone, imine, isocyanate, CO2, diazene, alkene, alkyne and epoxide. The results show that the highly polarized and electron-deficient bonds such as CO π bonds are readily activated, whereas 1f seems difficult to react with electron-rich unsaturated bonds of propene and propyne. More importantly, 1,3,2-diazaphospholene-based compounds, featuring an extremely polarized P–X bond (X = CCMe, NMe2, PMe2 and SMe), are predicted to have a useful catalytic ability. The preliminary computational results suggest that these P–X compounds could catalyze the silylamination, silylphosphination and silylsulfenylation of acetone with TMSNMe2, TMSPMe2 and TMSSMe, respectively. The products are silylethers, which are equivalent to the corresponding alcohols since they easily undergo hydrolysis. Our computational study opens a new avenue to the design of novel main group organocatalysts.