In an Attempt to Provide a User's Guide to the Galaxy of Benzylidene, Alkoxybenzylidene, and Indenylidene Ruthenium Olefin Metathesis Catalysts
作者:Michał Bieniek、Anna Michrowska、Dmitry L. Usanov、Karol Grela
DOI:10.1002/chem.200701340
日期:2008.1.18
tested. Interestingly, attempts to force a reaction by increasing the catalyst loading were much less effective. Therefore, when possible, it is suggested that metathesis transformations should be carried out with a second-generation catalyst at 70 degrees C in toluene. However, different second-generation catalysts proved to be optimal for different applications and no single catalyst outperformed all others
Liquid or supercritical carbon dioxide (scCO(2)) is a versatile reaction medium for ring-opening metathesis polymerization (ROMP) and ring-closing olefin metathesis (RCM) reactions using well-defined metal catalysts. The molybdenum alkylidene complex 1 and ruthenium carbenes 2 and 3 bearing PCy(3) or N-heterocyclic carbene ligands, respectively, can be used and are found to exhibit efficiency similar
Exchange of one PCy3 unit of the classical Grubbs catalyst 1 by N-heterocycliccarbene (NHC) ligands leads to "second-generation" metathesis catalysts of superior reactivity and increased stability. Several complexes of this type have been prepared and fully characterized, six of them by X-ray crystallography. These include the unique chelate complexes 13 and 14 in which the NHC- and the Ru-CR entities
N-Heterocyclic carbenes can coexist with alkenes and C–H acidic sites
作者:Alois Fürstner、Helga Krause、Lutz Ackermann、Christian W. Lehmann
DOI:10.1039/b107238b
日期:——
The isolation of compounds 3 and 7a,b proves that a singlet carbene center can coexist with alkenes or CâH acidic sites in proximity without spontaneous annihilation.