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首页> 外文期刊>Catalysis science & technology >Insight into the mechanism and site-selectivity of Rh-2(II,II)(esp)(2)-catalyzed intermolecular C-H amination
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Insight into the mechanism and site-selectivity of Rh-2(II,II)(esp)(2)-catalyzed intermolecular C-H amination

机译：洞察的机制和site-selectivityRh-2 (2, 2) (esp)(2)催化分子间碳氢键氨基化

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摘要

The mechanisms and site-selective determinants of Rh-2(II,II)(esp)(2)-catalyzed intermolecular C-H bond aminations of three isoamylbenzene-derived substrates, p-R-C6H4(CH2)(2)CH(CH3)(2) (R = OCH3, H, CF3), have been investigated by the density functional theory (BPW91) method. Our calculations show that both sigma-type and pi-type 3c/4e bonds exist in dirhodium nitrene Rh-2(esp)(2)-NSO3CH2CF3, and both the LUMO and SOMO2 of Rh-2-nitrene comprise a set of three-center (Rh-Rh-N) pi* orbitals. The three-center nature of these orbitals results in the nitrenoid nitrogen atom being of strong electrophilic reactivity, thus greatly facilitating C-H amination. A triplet stepwise pathway is favorable for Rh-2(II,II)(esp)(2)-catalyzed intermolecular C-H amination. Calculation results show that both electronic and steric effects are the principal determinants of the benzylic-to-tertiary ratio for intermolecular C-H amination of S-2. A theoretical examination of how para substituent R (R = OCH3, H, CF3) affects site-selectivity is also highlighted. The calculated isoamylbenzene benzylic-to-tertiary C-H amination ratio (B : T) is 12.8 : 1, which is in good agreement with the experimental value (B: T = 7.4 : 1). The para substituents impact the reactivity of the benzylic rather than the tertiary C-H bond by electronic effects. The strongly electron-donating substituent reduces the activation barrier of benzylic C-H amination via a p-p conjugation, thus the B: T product ratio is increased. The calculated B: T ratios of p-methoxy-isoamyl-benzene (S-1), isoamylbenzene (S-2) and p-trifluoromethyl-isoamylbenzene (S-3) follow the following trend: S-1 >> S-2 > S-3, which is in accordance with the experimental result reported by J. Du Bois' group.
机译：的机制和site-selective决定因素Rh-2 (2, 2) (esp)(2)催化分子间碳氢键债券三个isoamylbenzene-derived的氨基化基板,p-R-C6H4 (CH2) (2) CH (CH3) (2) (R =甲基,H,恶),研究了密度功能理论(BPW91)方法。计算表明,sigma-type和在dirhodium pi-type 3 c / 4 e债券存在氮烯Rh-2 (esp) (2) -NSO3CH2CF3, LUMO和SOMO2 Rh-2-nitrene组成一组3中心(Rh-Rh-N)π*轨道。这些轨道导致3中心的本质nitrenoid氮原子被强劲的亲电反应,从而极大地促进碳氢键氨基化。途径有利于Rh-2 (2, 2) (esp)(2)催化分子间碳氢键氨基化。电子和立体效果是校长benzylic-to-tertiary比率的决定因素分子间的碳氢键2氨基化。理论考试的对位取代基R(R =甲基、H、CF3)影响site-selectivity还强调了。benzylic-to-tertiary碳氢键氨基化比率(B: T)是12.8:1,这是在良好的协议吗实验值(T = 7.4: 1)。帕拉取代基的反应性的影响苄基的而不是叔碳氢键电子效应。电子基取代基减少了碳氢键活化势垒的苄基的氨基化通过一个p p接合,因此,B: T产品比率增加了。isoamylbenzene p-methoxy-isoamyl-benzene (s - 1)(2)和p-trifluoromethyl-isoamylbenzene (s 3)遵循以下趋势:s - 1 > > 2 > s 3,按照实验是哪一个结果报告的j·杜波依斯的小组。

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