Progress in their Design and Synthesis By V. U, Galveston, TXU. Article Synopsis This paper presents an up-to-date investigation relating to the design and synthesis of the recently disclosed single-site ruthenium carbene metathesis catalysts. Created as a convenient counterpart of the earlier tungsten and molybdenum carbene catalysts, these novel ruthenium carbene complexes bear specific heterocyclic ligands and display comparable activity and selectivity in metathesis reactions, as well as good tolerance toward organic functionalities, air and moisture.
This event is an appropriate sequel to the memorable Nobel Prize awarded to metathesis scientists Yves Chauvin, Robert H. Grubbs and Richard R. The purpose was to debate on the newest trends in olefin metathesis and identify future perspectives in this fascinating field of synthetic organic and organometallic chemistry, where platinum group metals pgmsespecially ruthenium, are playing a key role.
Olefin metathesis, one of the most efficient transition metal-mediated C—C bond forming reactions, has emerged during the last few years as a powerful synthetic strategy for obtaining fine chemicals, biologically active compounds, architecturally complex assemblies, new materials and functionalised polymers tailored for specific uses, including sensors, semiconductors and microelectronic devices.
Metathesis reactions, such as ring-closing metathesis RCMenyne metathesis, cross-metathesis CM and ring-opening metathesis polymerisation ROMPhave moved far beyond their 20th century boundaries.
This has resulted in a broad diversification towards sustainable technologies, and in new perspectives for a wide range of industrial applications, from production of smart, nanostructured materials to the manufacture of new pharmaceuticals 6—8.
During the meeting, recent advances in metathesis chemistry were disseminated among a selected audience of distinguished scientists and young researchers.
Wagener University of Florida, U. Such metathesis reactions have profound implications in materials science, nanotechnology, and also in organometallic, organic and polymer chemistry.
Developments in Ruthenium-Based Catalysts As expected, in lectures on catalyst-related topics emphasis was placed on the newest developments concerning ruthenium-based complexes of high activity, selectivity and robustness, popular for their excellent tolerance toward a variety of functional groups.
He included preparation methods and selected applications. In addition to the broad applications of the classical Schrock molybdenum catalysts and the Grubbs 1st and 2nd generationNolan or Hoveyda-type ruthenium catalysts, Dixneuf disclosed in a second seminal lecture: These applications refer specifically to the synthesis of new macrocycles via RCM, to RCM in the synthesis of new ligands, rotaxanes, catenanes and supramolecular systems, and to CM in organic synthesis and supramolecular system formation.
Elaborating on the essential role played by N-heterocyclic carbene NHC ligands in creating the most effective ruthenium metathesis catalysts for example, 4 and 5 vs. This provides an in-depth understanding of the RCM mechanism, to be exploited in synthesis of large and medium-sized rings.
A comparison between performances in CM of the new catalysts with those of the ill-defined catalysts based on tungsten was also presented. In this extremely broad context, several elegant applications of ruthenium dendritic structures were given for example, use of 6 in synthesis of polymers, 7.
New trends presently evolving in metathesis chemistry were critically discussed by Hynek Balcar J. The new directions cited were: Pertinent structural and mechanistic aspects regarding this recently introduced class of metathesis catalysts were also addressed.
This drew attention to a potentially important practical application of polymers obtained in this way galactose-functionalised polynorborneneswhich have so far proved successful in clinical trials for corneal tissue engineering.
Skeleton reorganisations, carried out with catalysts based on palladium, cobalt, rhodium, iridium, platinum, gold and ruthenium and involving electrophilic activation, oxidative coupling and metathesis reactions were described, along with applications of metathesis for the transformation of some natural compounds.
In the first, he highlighted the importance of both the presence and position of the oxygen substituent in norbornene derivatives subjected to ROMP, while also unambiguously establishing the identity of the propagating alkylidene species.
In his second lecture, by discussing two examples taken from their ongoing research: Debating on the correlation between the polymer structure and the gas transport parameters, he pointed out the role played by the occurrence, number and location of Me3Si-groups in a variety of copolymers synthesised for this purpose, as further reinforced by Maria Gringolts in a subsequent talk.
Substituted polyacetylenes having valuable conducting and optical properties could also be obtained by this straightforward methodology. Special attention was paid to addition polymerisation and copolymerisation of selected monomers such as silyl-functionalised norbornenesinduced by late transition metal catalysts nickel and palladiumproviding new materials with special properties high thermal and chemical stabilityfor applications such as optical components, electrical insulators and photoresists.
Concluding Remarks The social programme was organised in a friendly and warm style, facilitating informal scientific discussion among renowned experts and young researchers, and strengthening contacts and the exchange of information between research groups of different nationalities.
Comments from a number of participants converged to the idea that, in view of the current upward trend in developments in this field, organising further meetings would be both opportune and highly beneficial, especially for the young generation of scientists involved in metathesis research.
A major conclusion emerging from the lectures, posters and discussions at this Institute is that a principal focus in this highly challenging area of research is the advantages of using new ruthenium catalysts for a multitude of chemical transformations.
Further exploration of the metathesis chemistry of other pgms such as osmium is also of great interest. The application profile of the novel metathesis catalysts is expanding rapidly, particularly in RCM, and CM. These methods may be exploited for the synthesis of therapeutic compounds, as well as in ROMP for the production of specialised and highly functionalised polymers.
Following the useful practice of previous NATO ASI meetings see, for example, 9selected contributions including plenary lectures, short communications and posters will be compiled in a special volume dedicated to this outstanding scientific meeting, and will be published by Springer Verlag in Ruthenium Catalyzed Intramolecular Enyne Metathesis Mori first reported the use of the Grubbs catalyst for intramolecular enyne metathesis in (Equation 4).
12 Treatment of enyne 21 with 1 mol% of catalyst 18 gives cyclized diene New Developments in Cis-Selective Ruthenium Metathesis Catalysts November 22, By Diana Stoianova Since Daryl Allen wrote his post in on the development of the first cis -selective ruthenium catalysts with chelating NHC ligands, a lot of activity and exciting new developments occurred in the area which warrants an update.
Liaoning Provincial Key Laboratory for Green Synthesis and Preparative Chemistry of Advanced Materials, Liaoning University. College of Chemistry, Liaoning University. Ana María Lozano Vila was born in San José, Costa Rica, in She received the B.S. degree in chemistry and the Ph.D.
Ruthenium Catalyzed Intramolecular Enyne Metathesis Mori first reported the use of the Grubbs catalyst for intramolecular enyne metathesis in (Equation 4). 12 Treatment of enyne 21 with 1 mol% of catalyst 18 gives cyclized diene The main developments in ruthenium catalyst design for alkene metathesis covering the last 4 years is presented. These new catalysts are essentially based on modifications brought to Grubbs- or Hoveyda-type catalysts and the generation of catalysts by activation of propargyl derivatives leading to ruthenium–allenylidene, – indenylidene, and alkenylcarbene catalysts. First published on 16th June While the fundamental series of [2+2]cycloadditions and retro[2+2]cycloadditions that make up the pathways of ruthenium-catalysed metathesis reactions is well-established, the exploration of mechanistic aspects of alkene metathesis continues.
The catalyst thus prepared was active in the self-metathesis of internal alkenes as well as in ring-closing metathesis. It was easily separated from the reaction products, which were almost free from ruthenium contamination, and also recycled.
the last 4 years in the design of alkene metathesis ruthenium catalysts based [6,7,8], and third-generation  Grubbs- and Hoveyda-type catalysts will be Abstract: The main developments in ruthenium catalyst design for alkene metathesis.
In addition to the broad applications of the classical Schrock molybdenum catalysts and the Grubbs (1st and 2nd generation), Nolan or Hoveyda-type ruthenium catalysts, Dixneuf disclosed in a second seminal lecture: ‘Recent Applications of Alkene Metathesis for Fine Chemical and Supramolecular System Synthesis’, further significant.