Amine-Mediated Degradation in Olefin Metathesis Reactions that Employ the Second-Generation Grubbs Catalyst

ChemCatChem ◽  
2014 ◽  
Vol 6 (2) ◽  
pp. 459-463 ◽  
Author(s):  
Justin A. M. Lummiss ◽  
Benjamin J. Ireland ◽  
Jacob M. Sommers ◽  
Deryn E. Fogg
Keyword(s):  
Olefin Metathesis ◽  
Second Generation ◽  
Grubbs Catalyst ◽  
Metathesis Reactions

Operation of the Boomerang Mechanism in Olefin Metathesis Reactions Promoted by the Second-Generation Hoveyda Catalyst

ACS Catalysis ◽  
2014 ◽  
Vol 4 (7) ◽  
pp. 2387-2394 ◽  
Author(s):  
Jennifer M. Bates ◽  
Justin A. M. Lummiss ◽  
Gwendolyn A. Bailey ◽  
Deryn E. Fogg
Keyword(s):  
Olefin Metathesis ◽  
Second Generation ◽  
Metathesis Reactions

A thermally robust ruthenium phosphonium alkylidene catalyst — the effect of more bulky N-heterocyclic carbene ligands on catalyst performance in olefin metathesis reactions

2013 ◽  
Vol 91 (10) ◽  
pp. 935-942 ◽  
Author(s):  
Erin M. Leitao ◽  
Warren E. Piers ◽  
Masood Parvez
Keyword(s):  
Olefin Metathesis ◽  
Second Generation ◽  
The Other ◽  
Carbene Ligands ◽  
Thermal Stabilities ◽  
Excellent Activity ◽  
Metathesis Reactions ◽  
Test Reactions ◽  
Overall Efficiency ◽  
Alkylidene Complexes

Three new ruthenium phosphonium alkylidene complexes incorporating N-heterocyclic carbene ligands with bulky N-aryl groups (2,6-diethyl, L = 1,3-bis(2,6-diethylphenyl)imidazolin-2-ylidene (H2IDEP) and 2,6-diisopropyl, L = 1,3-bis(2,6-diisopropylphenyl)imidazolin-2-ylidene (H2ID-i-PP)) were synthesized and characterized. The H2ID-i-PP supported complex was found to exhibit excellent thermal stabilities relative to the parent N-mesityl (N-Mes) complexes as well as the H2IDEP supported complexes. All three phosphonium alkylidenes were evaluated in comparison to the N-Mes derivative and Grubbs second generation catalyst using standard olefin metathesis reactions and conditions. The complex containing the bulky H2ID-i-PP ligand was found to have excellent activity and longevity in comparison to the other catalysts. Although initiation rates were slow for this sterically bulky precatalyst, its superior activity led to the best overall efficiency in test reactions.

scholarly journals The Influence of Various N-Heterocyclic Carbene Ligands on Activity of Nitro-Activated Olefin Metathesis Catalysts

Molecules ◽  
2020 ◽  
Vol 25 (10) ◽  
pp. 2282 ◽  
Author(s):  
Michał Pieczykolan ◽  
Justyna Czaban-Jóźwiak ◽  
Maura Malinska ◽  
Krzysztof Woźniak ◽  
Reto Dorta ◽  
...  
Keyword(s):  
High Activity ◽  
Olefin Metathesis ◽  
Double Bonds ◽  
Carbene Ligands ◽  
Grubbs Catalyst ◽  
Metathesis Reactions ◽  
Metathesis Catalysts

A set of nitro-activated ruthenium-based Hoveyda-Grubbs type olefin metathesis catalysts bearing sterically modified N-hetero-cyclic carbene (NHC) ligands have been obtained, characterised and studied in a set of model metathesis reactions. It was found that catalysts bearing standard SIMes and SIPr ligands (4a and 4b) gave the best results in metathesis of substrates with more accessible C–C double bonds. At the same time, catalysts bearing engineered naphthyl-substituted NHC ligands (4d–e) exhibited high activity towards formation of tetrasubstituted C–C double bonds, the reaction which was traditionally Achilles’ heel of the nitro-activated Hoveyda–Grubbs catalyst.

Olefin metathesis, p‐Cresol and the Second Generation Grubbs Catalyst:  Fitting the Pieces

2021 ◽  
Author(s):  
Marthinus Rudi Swart ◽  
Linette Twigge ◽  
Elizabeth Erasmus ◽  
Charlene Marais ◽  
Barend Christiaan Bezuidenhoudt
Keyword(s):  
Olefin Metathesis ◽  
Second Generation ◽  
Grubbs Catalyst

scholarly journals A comprehensive study of olefin metathesis catalyzed by Ru-based catalysts

2015 ◽  
Vol 11 ◽  
pp. 1767-1780 ◽  
Author(s):  
Albert Poater ◽  
Luigi Cavallo
Keyword(s):  
Dft Calculations ◽  
Olefin Metathesis ◽  
Second Generation ◽  
Phosphine Ligands ◽  
Grubbs Catalyst ◽  
Heterocyclic Ligand ◽  
Grubbs Catalysts ◽  
Wide Range ◽  
First And Second Generation ◽  
Comprehensive Study

During a Ru-catalyzed reaction of an olefin with an alkylidene moiety that leads to a metallacycle intermediate, the cis insertion of the olefin can occur from two different directions, namely side and bottom with respect to the phosphine or N-heterocyclic ligand (NHC), depending on the first or second generation Grubbs catalyst. Here, DFT calculations unravel to which extent the bottom coordination of olefins with respect is favored over the side coordination through screening a wide range of catalysts, including first and second generation Grubbs catalysts as well as the subsequent Hoveyda derivatives. The equilibrium between bottom and side coordination is influenced by sterics, electronics, and polarity of the solvent. The side attack is favored for sterically less demanding NHC and/or alkylidene ligands. Moreover the generation of a 14-electron species is also discussed, with either pyridine or phosphine ligands to dissociate.

Catalytic Carbonyl-Olefin Metathesis of Aliphatic Ketones: Iron(III) HomoDimers as Lewis Acidic Superelectrophiles

2018 ◽  
Author(s):  
Haley Albright ◽  
Paul S. Riehl ◽  
Christopher C. McAtee ◽  
Jolene P. Reid ◽  
Jacob R. Ludwig ◽  
...  
Keyword(s):  
Lewis Acid ◽  
Olefin Metathesis ◽  
Acid Activation ◽  
Lewis Acid Catalysts ◽  
Distinct Mode ◽  
Aliphatic Ketones ◽  
Carbon Carbon Bond ◽  
Metathesis Reactions ◽  
Acid Catalyzed

<div>Catalytic carbonyl-olefin metathesis reactions have recently been developed as a powerful tool for carbon-carbon bond</div><div>formation. However, currently available synthetic protocols rely exclusively on aryl ketone substrates while the corresponding aliphatic analogs remain elusive. We herein report the development of Lewis acid-catalyzed carbonyl-olefin ring-closing metathesis reactions for aliphatic ketones. Mechanistic investigations are consistent with a distinct mode of activation relying on the in situ formation of a homobimetallic singly-bridged iron(III)-dimer as the active catalytic species. These “superelectrophiles” function as more powerful Lewis acid catalysts that form upon association of individual iron(III)-monomers. While this mode of Lewis acid activation has previously been postulated to exist, it has not yet been applied in a catalytic setting. The insights presented are expected to enable further advancement in Lewis acid catalysis by building upon the activation principle of “superelectrophiles” and broaden the current scope of catalytic carbonyl-olefin metathesis reactions.</div>

New pseudohalide ligands in Ru-catalyzed olefin metathesis — A robust, air-activated iminopyrrolato catalyst

2005 ◽  
Vol 83 (6-7) ◽  
pp. 748-754 ◽  
Author(s):  
Samantha D Drouin ◽  
Heather M Foucault ◽  
Glenn PA Yap ◽  
Deryn E Fogg
Keyword(s):  
Key Words ◽  
Olefin Metathesis ◽  
High Reactivity ◽  
Ring Closing Metathesis ◽  
Grubbs Catalyst ◽  
X Ray ◽  
X Ray Crystallography

Reaction of the Grubbs catalyst RuCl2(PCy3)2(CHPh) (1) with lithium 2-[(2,6-diisopropylphenyl)imino]pyrrolide·Et2O (LiNN′·Et2O) gives alkylidene complex 5, containing a chelating, σ-bound iminopyrrolato unit. The structure of 5 is confirmed by X-ray crystallography. Treatment of 5 with pyridine generates RuCl(NN′)(py)2(CHPh) (6) via displacement of PCy3. Complex 5 effects ring-closing metathesis in air, displaying high reactivity relative to 6.Key words: ruthenium, alkylidene, metathesis, pyrrolimine, iminopyrrolato.

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