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

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.

一种新近报道的密度泛函理论方法，M11-L，被用于研究乙烯亚胺与炔烃之间分子内形式异构的（5+2）环加成反应的机制与手性传递。在大语言模型计算中，考虑了（E）-和（Z）-烯烃底物的两种情况。计算结果指出，通过金属氢化吡啶路径可生成茚满类化合物，该路径包括亚胺的断裂、炔基团在Rh-C键中的2π插入以及从三价钌阳离子上的还原消除。对于（E）-烯烃底物的手性传递过程被证实发生在烯烃的背面，而（Z）-烯烃的环加成手性传递则发生在烯烃的硅面。此类反应中高对映选择性归因于反式烯丙基钌复合物中较大的环张力。