Through the combined use of computational (density functional theory) and experimental studies, a new [Rh(CO)2Cl]2 catalyzed two-component [5+2+1] cycloaddition of ene-vinylcyclopropanes and CO for the synthesis of fused bicyclic cyclooctenones has been designed and experimentally realized. The key point behind this design is to turn a disfavored reductive elimination of (sp3)C−Rh−C(sp3) to an easier
通过计算(密度泛函理论)和实验研究的结合,一种新的 [Rh(CO)2Cl]2 催化烯-乙烯基环丙烷和 CO 的双组分 [5+2+1] 环加成反应合成稠合双环环辛酮已经设计并实验实现。这种设计背后的关键点是通过引入 CO 将 (sp3)C-Rh-C(sp3) 的不利还原消除转变为更容易迁移的 (sp3)C-Rh-CO-C(sp3) 还原消除这些反应对于具有各种系链类型和取代基的底物以良好的产率进行,为双环环辛烯酮的构建提供了灵活、方便、高效和立体控制的方法。
Mechanism and Stereochemistry of Rhodium-Catalyzed [5 + 2 + 1] Cycloaddition of Ene–Vinylcyclopropanes and Carbon Monoxide Revealed by Visual Kinetic Analysis and Quantum Chemical Calculations
transfer steps. Other reaction pathways have also been considered but then have been ruled out. The steric origin of the diastereoselectivity (cis versus trans) was revealed by comparing the alkene insertion transition states. In addition, how the double-bond configuration of the VCPs (Z versus E) affects the substrate reactivity and the origins of chemoselectivity ([5 + 2 + 1] versus [5 + 2]) were also investigated
Asymmetric Catalysis of the [5 + 2] Cycloaddition Reaction of Vinylcyclopropanes and π-Systems
作者:Paul A. Wender、Lars O. Haustedt、Jaehong Lim、Jennifer A. Love、Travis J. Williams、Joo-Yong Yoon
DOI:10.1021/ja058590u
日期:2006.5.1
our studies of metal-catalyzed [m + n (+...o)] cycloadditions, we have previously reported the rhodium-catalyzed [5 + 2] cycloaddition of vinylcyclopropanes (VCPs) and pi-systems. These studies have led to Rh(I) complexes that catalyze these reactions in minutes at room temperature or in water without organic solvents. We describe a comparative evaluation of several chiral catalysts for the [5 + 2]