Rhodium-Catalyzed Hetero-(5 + 2) Cycloaddition of Vinylaziridines and Alkynes: A Theoretical View of the Mechanism and Chirality Transfer

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• 作者：Lei Zhu ; Xiaotian Qi ; Yu Lan
• 刊名：Organometallics
• 出版年：2016
• 出版时间：March 14, 2016
• 年：2016
• 卷：35
• 期：5
• 页码：771-777
• 全文大小：603K
• ISSN：1520-6041

文摘

A newly reported density functional theory method, M11-L, was performed to study the mechanism and chirality transfer for the intramolecular formal hetero-(5 + 2) cycloaddition of vinylaziridines with alkynes. Both (E)- and (Z)-olefinic substrates were considered in the density functional theory calculations. The computational results suggested a metallahydropyridine pathway for the generation of azepines, which involves aziridine cleavage, 2π insertion of the alkyne group into the Rh–C bond, and reductive elimination from a rhodium(III) cation. The chirality transfer process for the (E)-alkene substrate is shown to occur on the re face of the alkene, whereas the (Z)-alkene cycloaddition chirality transfer occurs on the si face. The high enantioselectivity in this type of reaction is attributed to the greater ring strain in the trans allylic rhodium complex.