期刊
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
卷 135, 期 4, 页码 1456-1462出版社
AMER CHEMICAL SOC
DOI: 10.1021/ja309873z
关键词
-
资金
- National Science Foundation [CHE-0548209]
- NSF [OCI-1053575]
- Direct For Mathematical & Physical Scien [1059084] Funding Source: National Science Foundation
- Division Of Chemistry [1059084] Funding Source: National Science Foundation
The mechanism and origins of selectivities in [Ni(NHC)]-catalyzed intramolecular (5 + 2) cycloadditions and homo-ene reactions of vinylcyclopropanes (VCPs) and alkynes have been studied using density functional theory. The preferred mechanism involves oxidative alkyne-alkene cyclization to form a metallacyclopentene intermediate, in contrast to a cyclopropane cleavage pathway in the reaction with Rh(I) catalysts. The selectivity between the (5 + 2) and homo-ene products is determined in the subsequent competing reductive elimination and beta-hydride elimination steps. Two similar-sized N-heterocyclic carbene (NHC) ligands, SIPr and ItBu, yielded reversed product selectivity, favoring the (5 + 2) and homo-ene products respectively. This is attributed to the anisotropic steric environment of these NHC ligands, which positions the bulky substituents on the ligand toward different directions and leads to distinct steric control in the reductive elimination and beta-hydride elimination transition states.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据