Rhodium(ii)-catalyzed C–H aminations using N-mesyloxycarbamates: reaction pathway and by-product formation†,Chemical Science

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Rhodium(ii)-catalyzed C–H aminations using N-mesyloxycarbamates: reaction pathway and by-product formation†
Chemical Science ( IF 7.6 ) Pub Date : 2018-10-22 00:00:00 , DOI: 10.1039/c8sc03153c
Emna Azek ₁ , Maroua Khalifa ₁ , Johan Bartholoméüs ₁ , Matthias Ernzerhof ₁ , Hélène Lebel ₁

Affiliation

N-Mesyloxycarbamates are practical nitrene precursors that undergo C–H amination reactions in the presence of rhodium dimer catalysts. Under these conditions, both oxazolidinones and chiral amines have been prepared in a highly efficient manner. Given the elevated reactivity of the intermediates involved in the catalytic cycle, mechanistic details have remained hypothetical, relying on indirect experiments. Herein a density functional theory (DFT) study is presented to validate the catalytic cycle of the rhodium-catalyzed C–H amination with N-mesyloxycarbamates. A concerted pathway involving Rh–nitrene species that undergoes C–H insertion is found to be favored over a stepwise C–N bond formation manifold. Density functional calculations and kinetic studies suggest that the rate-limiting step is the C–H insertion process rather than the formation of Rh–nitrene species. In addition, these studies provide mechanistic details about competitive by-product formation, resulting from an intermolecular reaction between the Rh–nitrene species and the N-mesyloxycarbamate anion.

中文翻译：

使用 N-甲磺氧基氨基甲酸酯进行铑 (ii) 催化的 C–H 胺化：反应途径和副产物形成†

N-甲磺氧基氨基甲酸酯是实用的氮烯前体，在铑二聚体催化剂存在下发生 C-H 胺化反应。在这些条件下，恶唑烷酮和手性胺都以高效的方式制备。鉴于催化循环中涉及的中间体的反应性升高，依赖于间接实验，机制细节仍然是假设的。本文提出了密度泛函理论 (DFT) 研究，以验证铑催化的 C-H 胺化与N-甲磺酰氧基氨基甲酸酯的催化循环。研究发现，涉及经历 C-H 插入的 Rh-氮烯物种的协同途径优于逐步的 C-N 键形成流形。密度泛函计算和动力学研究表明限速步骤是C-H插入过程而不是Rh-氮烯物种的形成。此外，这些研究还提供了有关竞争性副产物形成的机制细节，该副产物是由Rh-氮烯物种和N-甲磺酰氧基氨基甲酸酯阴离子之间的分子间反应产生的。

更新日期：2018-10-22

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