Intriguing substituent effect in modified Hoveyda-Grubbs metathesis catalysts incorporating a chelating iodo-benzylidene ligand.
نویسندگان
چکیده
A series of modified Hoveyda-Grubbs catalysts incorporating a chelating iodo-benzylidene ligand were prepared and characterized. The presence of electron-withdrawing ring substituents in the para position to the iodide was found to decrease the catalytic activity, revealing that dissociation of the Ru···I-Ar bond is not the rate-determining step.
منابع مشابه
Phase Tags in the Recycling of Homogeneous Grubbs Catalysts
Since they were first synthesized in 1992, the ruthenium catalyst named after Nobel Laureate R. H. Grubbs have become a useful tool in organic synthesis. Compared to conventional heterogeneous metathesis catalysts, Grubbs catalysts are more reactive, faster to initiate and better for reaction control. Grubbs catalysts have been employed in good effort both in academia and industry, the later in...
متن کاملDeactivation of ruthenium olefin metathesis catalysts through intramolecular carbene-arene bond formation.
for olefin metathesis have been reported, for which strikingly different influences of the ligands on the efficiency of C C bond formation have been observed. For example, notable effects have been found in the class of alkoxy benzylidene ligands first introduced by Hoveyda and coworkers. Phosphine-free complexes such as the secondgeneration Hoveyda–Grubbs catalyst (4 ; IMesH2= 1,3-dimesityl-4,...
متن کاملSimple activation by acid of latent Ru-NHC-based metathesis initiators bearing 8-quinolinolate co-ligands
A straightforward synthesis utilizing the ring-opening metathesis polymerization (ROMP) reaction is described for acid-triggered N,O-chelating ruthenium-based pre-catalysts bearing one or two 8-quinolinolate ligands. The innovative pre-catalysts were tested regarding their behavior in ROMP and especially for their use in the synthesis of poly(dicyclopentadiene) (pDCPD). Bearing either the commo...
متن کاملOrigins of initiation rate differences in ruthenium olefin metathesis catalysts containing chelating benzylidenes.
A series of second-generation ruthenium olefin metathesis catalysts was investigated using a combination of reaction kinetics, X-ray crystallography, NMR spectroscopy, and DFT calculations in order to determine the relationship between the structure of the chelating o-alkoxybenzylidene and the observed initiation rate. Included in this series were previously reported catalysts containing a vari...
متن کاملNew library of aminosulfonyl-tagged Hoveyda–Grubbs type complexes: Synthesis, kinetic studies and activity in olefin metathesis transformations
Seven novel Hoveyda-Grubbs precatalysts bearing an aminosulfonyl function are reported. Kinetic studies indicate an activity enhancement compared to Hoveyda's precatalyst. A selection of these catalysts was investigated with various substrates in ring-closing metathesis of dienes or enynes and cross metathesis. The results demonstrate that these catalysts show a good tolerance to various chemic...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
- Dalton transactions
دوره 42 2 شماره
صفحات -
تاریخ انتشار 2013