Mechanism of Rhodium-Catalyzed Intramolecular Hydroacylation: A Computational Study

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• 作者：I. F. Dempsey Hyatt ; Heather K. Anderson ; Andrew T. Morehead Jr. ; Andrew L. Sargent
• 刊名：Organometallics
• 出版年：2008
• 出版时间：January 14, 2008
• 年：2008
• 卷：27
• 期：1
• 页码：135 - 147
• 全文大小：2203K
• 年卷期：v.27,no.1(January 14, 2008)
• ISSN：1520-6041

文摘

All-electron numerical density functional theory calculations with scalar relativistic corrections have been utilized to examine the mechanism of the intramolecular rhodium-catalyzed hydroacylation reaction. The gas-phase results reveal a key branch point early in the reaction at the oxidative addition step wherein the two important pathways evolve through five-coordinate Rh(III) intermediates characterized by an apical acyl group and an equatorial hydride, orientations seemingly counter to trans influence arguments. These pathways account for the gross features of the experimental product distribution as well as the isotope labeling outcomes observed by previous investigators in this area. A greatly simplified approximation to modeling the reaction environment was applied that focused on redressing the coordinative unsaturation prevalent during certain steps of the catalytic process by including an explicit molecule of solvent or an additional molecule of substrate. Such an approach allowed us to explain the catalytic deactivation, substrate inhibition and dependence of the reaction rate on this coordinated ligand. Importantly, the application of a popular QM/MM method was unable to locate some of the key stationary points along the reaction path.