Inside the black box — Perspectives on transformations in catalysis

2008 ◽  
Vol 86 (10) ◽  
pp. 931-941 ◽  
Author(s):  
Deryn E Fogg
Keyword(s):  
Green Chemistry ◽  
Olefin Metathesis ◽  
Catalyst Activity ◽  
Black Box ◽  
Tandem Catalysis ◽  
Ring Closing Metathesis ◽  
Metathesis Catalysts ◽  
Tandem Metathesis

Tandem catalysis and olefin metathesis are powerful tools in the development of sustainable synthetic practices. This Award Lecture describes our advances in designing new tandem metathesis-hydrogenation methodologies for the synthesis of “designer materials” and Ru-pseudohalide metathesis catalysts that amplify opportunities for tuning catalyst activity, selectivity, and lifetime. Also discussed is the operation of a previously unrecognized oligomerization-backbiting pathway in ring-closing metathesis of conformationally flexible α,ω-dienes, which has important implications for the sustainable synthesis of medium and large rings.Key words: tandem catalysis, green chemistry, olefin metathesis, ring-closing metathesis, mechanism.

Hindered Rotation in New Air-Stable Ruthenium Olefin Metathesis Catalysts with Chromanylmethylidene Ligands

2009 ◽  
Vol 62 (10) ◽  
pp. 1363 ◽  
Author(s):  
Agnieszka Hryniewicka ◽  
Jacek W. Morzycki ◽  
Leszek Siergiejczyk ◽  
Stanisław Witkowski ◽  
Jacek Wójcik ◽  
...  
Keyword(s):  
Olefin Metathesis ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Asymmetric Induction ◽  
Dynamic Nmr ◽  
Nmr Analysis ◽  
Ring Closing Metathesis ◽  
Hindered Rotation ◽  
Metathesis Catalysts ◽  
First Time

Three new ruthenium complexes with chromanylmethylidene ligands were synthesized and dynamic NMR analysis of these compounds was carried out. The activation energy for the C–Ru rotation was measured for the first time and found to be of ~60 kJ mol–1. The complexes may potentially serve as latent catalysts for olefin metathesis – they promote the simple ring-closing metathesis reactions very slowly at room temperature, but are much more active at slightly elevated temperatures. No asymmetric induction was observed when the chiral α-tocopherol-derived catalyst was used.

scholarly journals Profluorescent substrates for the screening of olefin metathesis catalysts

2015 ◽  
Vol 11 ◽  
pp. 1886-1892 ◽  
Author(s):  
Raphael Reuter ◽  
Thomas R Ward
Keyword(s):  
Olefin Metathesis ◽  
Fluorescent Assay ◽  
Ring Closing Metathesis ◽  
Plate Assay ◽  
Metathesis Catalysts

Herein we report on a 96-well plate assay based on the fluorescence resulting from the ring-closing metathesis of two profluorophoric substrates. To demonstrate the validity of the approach, four commercially available ruthenium-metathesis catalysts were evaluated in six different solvents. The results from the fluorescent assay agree well with HPLC conversions, validating the usefulness of the approach.

scholarly journals Halide exchanged Hoveyda-type complexes in olefin metathesis

2010 ◽  
Vol 6 ◽  
pp. 1091-1098 ◽  
Author(s):  
Julia Wappel ◽  
César A Urbina-Blanco ◽  
Mudassar Abbas ◽  
Jörg H Albering ◽  
Robert Saf ◽  
...  
Keyword(s):  
Olefin Metathesis ◽  
Ring Opening ◽  
Catalytic Performance ◽  
Ring Closing Metathesis ◽  
Cross Metathesis ◽  
Metathesis Reactions ◽  
Metathesis Catalysts

The aims of this contribution are to present a straightforward synthesis of 2nd generation Hoveyda-type olefin metathesis catalysts bearing bromo and iodo ligands, and to disclose the subtle influence of the different anionic co-ligands on the catalytic performance of the complexes in ring opening metathesis polymerisation, ring closing metathesis, enyne cycloisomerisation and cross metathesis reactions.

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.

Activated Hoveyda‐Grubbs Olefin Metathesis Catalysts Derived from a Large Scale Produced Pharmaceutical Intermediate—Sildenafil Aldehyde

2021 ◽  
Author(s):  
Louis Monsigny ◽  
Jakub Piątkowski ◽  
Damian Trzybiński ◽  
Krzysztof Wozniak ◽  
Tomasz Nienałtowski ◽  
...  
Keyword(s):  
Olefin Metathesis ◽  
Large Scale ◽  
Metathesis Catalysts

Nitrenium ions and trivalent boron ligands as analogues of N-heterocyclic carbenes in olefin metathesis: a computational study

2015 ◽  
Vol 44 (46) ◽  
pp. 20021-20026 ◽  
Author(s):  
A. Pazio ◽  
K. Woźniak ◽  
K. Grela ◽  
B. Trzaskowski
Keyword(s):  
Olefin Metathesis ◽  
Computational Study ◽  
Heterocyclic Carbenes ◽  
Mechanistic Study ◽  
Nitrenium Ions ◽  
Nitrenium Ion ◽  
Metathesis Catalysts

A DFT mechanistic study reveals that nitrenium ion-modified Hoveyda-like complexes are good candidates for latent metathesis catalysts, while boron-modified systems are candidates for very fast metathesis catalysts.

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