Mechanism of the Ni(0)-Catalyzed Vinylcyclopropane−Cyclopentene Rearrangement
作者:Selina C. Wang、Dawn M. Troast、Martin Conda-Sheridan、Gang Zuo、Donna LaGarde、Janis Louie、Dean J. Tantillo
DOI:10.1021/jo901525u
日期:2009.10.16
A combination of physical organic experiments and quantum chemical calculations were used to construct a detailed mechanistic model for the Ni(0)-N-heterocyclic carbene-catalyzed vinylcyclo-propane-cyclopentene rearrangement that involves a mutistep oxidative addition/haptotropic shift/reductive elimination pathway. No evidence for the intermediacy of radicals or zwitterions was found. The roles of substituents on the vinylcyclopropane substrate and variations in the ligands on Ni were evaluated. It is postulated that bulky carbene ligands facilitate formation of the active catalyst species.