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Special Issue "Olefin Metathesis and Its Application"

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A special issue of Molecules (ISSN 1420-3049).

Deadline for manuscript submissions: closed (31 March 2012)

Special Issue Editor

Guest Editor
Dr. Anna G. Wenzel

Joint Science Department, Claremont McKenna, Pitzer and Scripps Colleges, Claremont, California 91711, USA
E-Mail
Interests: asymmetric catalysis; organometallic cemistry; organic synthesis

Special Issue Information

Dear Colleagues,

The reliable and efficient generation of carbon-carbon bonds underpins the foundation of chemical synthesis. Of these, olefin metathesis has risen to the forefront of the methods utilized for the preparation of alkenes. Catalyst developments in the past 25 years have dramatically increased the accessibility of this reaction for general use, with many catalysts now being commercially available. In addition, significant progress has been made in understanding the catalyst and substrate structural features, their interactions, and experimental conditions crucial to reaction selectivity. This has led to numerous applications of olefin metathesis in both academia and industry. In particular, cross-metathesis, ring-closing metathesis, enyne metathesis, ring-rearrangement metathesis, as well as tandem processes, remain highly active areas of investigation.

Despite the progress that has been achieved, many challenges remain, principally with regard to catalyst stability and control. The issue of control manifests itself in a myriad of ways, be it regiochemical or stereochemical. For example, the issue of olefin diastereocontrol in metathesis remains a significant challenge due to the thermodynamic nature of the reaction. Additionally, the pursuit of substrate control, while maintaining high catalyst turnover numbers in the face of steric and electronic impediments, remains a significant goal of catalyst design. Fortunately, recent years have seen many elegant solutions towards progress in overcoming these hurdles.

This Special Issue on olefin metathesis will offer an attractive forum to present recent results in olefin metathesis pertaining to catalyst development, broadened substrate scope and/or stereocontrol, as well as the application of olefin metathesis to synthesis. I strongly encourage authors to submit papers for Molecules’ Special Issue on Olefin Metathesis. I believe that the topics covered will thoroughly convey the expanding potential and applicability of this versatile reaction.

Dr. Anna G. Wenzel
Guest Editor

Keywords

  • olefin metathesis
  • ruthenium
  • molybdenum
  • transition metal
  • alkylidene
  • catalytic

Published Papers (6 papers)

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Research

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Open AccessArticle Metathesis Transformations of Natural Products: Cross-Metathesis of Natural Rubber and Mandarin Oil by Ru-Alkylidene Catalysts
Molecules 2012, 17(5), 6001-6010; doi:10.3390/molecules17056001
Received: 16 March 2012 / Revised: 30 April 2012 / Accepted: 3 May 2012 / Published: 18 May 2012
Cited by 12 | PDF Full-text (245 KB)
Abstract
This study reports on the degradation of natural rubber (NR) via cross-metathesis with mandarin oil and d-limonene, an abundant compound in essential oils; that were used as chain transfer agents (CTAs) and green solvents. Reactions were performed in the presence of the
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This study reports on the degradation of natural rubber (NR) via cross-metathesis with mandarin oil and d-limonene, an abundant compound in essential oils; that were used as chain transfer agents (CTAs) and green solvents. Reactions were performed in the presence of the ruthenium-alkylidene catalysts (PCy3)2(Cl)2Ru=CHPh (I) and (1,3-dimesityl-4,5-dihydroimidazol-2-ylidene) (PCy3)Cl2Ru=CHPh (II), respectively. Catalyst II bears an N-heterocyclic carbene ligand (NHC) bounded to the ruthenium atom, which has a strong basic character; therefore it is more active toward trisubstituted olefins in comparison with catalyst I. In both cases, isolated monoterpene-terminated isoprene oligomers were obtained as products of the cross-metathesis degradation of NR. In the presence of catalyst II molecular weight values around Mn × 102 and yields of 80% were obtained; whereas with catalyst I, the molecular weights of products were about Mn × 104 with yields ranging 70 to 74%. The composition and yield of NR degradation products were determined by GC/MS (EI) analysis and it was found that the oligomers obtained have primarily one vinyl group and one terpene-monocyclic group at the chain end, with isoprene units Am = 2, 3 y 4. Full article
(This article belongs to the Special Issue Olefin Metathesis and Its Application)
Open AccessArticle Development of a Method for the Preparation of Ruthenium Indenylidene-Ether Olefin Metathesis Catalysts
Molecules 2012, 17(5), 5675-5689; doi:10.3390/molecules17055675
Received: 28 March 2012 / Revised: 18 April 2012 / Accepted: 23 April 2012 / Published: 11 May 2012
Cited by 9 | PDF Full-text (345 KB)
Abstract
The reactions between several derivatives of 1-(3,5-dimethoxyphenyl)-prop-2-yn-1-ol and different ruthenium starting materials [i.e., RuCl2(PPh3)3 and RuCl2(p-cymene)(L), where L is tricyclohexylphosphine di-t-butylmethylphosphine, dicyclohexylphenylphosphine, triisobutylphosphine, triisopropylphosphine, or tri-n-propylphosphine] are described. Several of
[...] Read more.
The reactions between several derivatives of 1-(3,5-dimethoxyphenyl)-prop-2-yn-1-ol and different ruthenium starting materials [i.e., RuCl2(PPh3)3 and RuCl2(p-cymene)(L), where L is tricyclohexylphosphine di-t-butylmethylphosphine, dicyclohexylphenylphosphine, triisobutylphosphine, triisopropylphosphine, or tri-n-propylphosphine] are described. Several of these reactions allow for the easy, in-situ and atom-economic preparation of olefin metathesis catalysts. Organic precursor 1-(3,5-dimethoxyphenyl)-1-phenyl-prop-2-yn-1-ol led to the formation of active ruthenium indenylidene-ether complexes, while 1-(3,5-dimethoxyphenyl)-prop-2-yn-1-ol and 1-(3,5-dimethoxyphenyl)-1-methyl-prop-2-yn-1-ol did not. It was also found that a bulky and strong σ-donor phosphine ligand was required to impart good catalytic activity to the new ruthenium complexes. Full article
(This article belongs to the Special Issue Olefin Metathesis and Its Application)
Open AccessCommunication Synthesis of Electronically Modified Ru-Based Neutral 16 VE Allenylidene Olefin Metathesis Precatalysts
Molecules 2012, 17(5), 5177-5186; doi:10.3390/molecules17055177
Received: 1 April 2012 / Revised: 25 April 2012 / Accepted: 26 April 2012 / Published: 4 May 2012
Cited by 8 | PDF Full-text (359 KB)
Abstract
Electronic modifications within Ru-based olefin metathesis precatalysts have provided a number of new complexes with significant differences in reactivity profiles. So far, this aspect has not been studied for neutral 16 VE allenylidenes. The first synthesis of electronically altered complexes of this type
[...] Read more.
Electronic modifications within Ru-based olefin metathesis precatalysts have provided a number of new complexes with significant differences in reactivity profiles. So far, this aspect has not been studied for neutral 16 VE allenylidenes. The first synthesis of electronically altered complexes of this type is reported. Following the classical dehydration approach (vide infra) modified propargyl alcohols were transformed to the targeted allenylidene systems in the presence of PCy3. The catalytic performance was investigated in RCM reaction (ring closing metathesis) of benchmark substrates such as diallyltosylamide (6) and diethyl diallylmalonate (7). Full article
(This article belongs to the Special Issue Olefin Metathesis and Its Application)

Review

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Open AccessReview Synthesis of Tetrasubstituted Alkenes via Metathesis
Molecules 2012, 17(3), 3348-3358; doi:10.3390/molecules17033348
Received: 28 February 2012 / Revised: 7 March 2012 / Accepted: 13 March 2012 / Published: 15 March 2012
Cited by 18 | PDF Full-text (463 KB)
Abstract Fully substituted olefin generation via metathesis is presented. Catalyst development, optimization of reaction conditions and substrate screening are included. In addition, asymmetric alkene metathesis, the cross metathesis reaction for this transformation and its application in natural products will be discussed. Full article
(This article belongs to the Special Issue Olefin Metathesis and Its Application)
Open AccessReview One Step Formation of Propene from Ethene or Ethanol through Metathesis on Nickel Ion-loaded Silica
Molecules 2011, 16(9), 7844-7863; doi:10.3390/molecules16097844
Received: 30 June 2011 / Revised: 4 August 2011 / Accepted: 5 September 2011 / Published: 13 September 2011
Cited by 25 | PDF Full-text (1975 KB)
Abstract
Increased propene production is presently one of the most significant objectives in petroleum chemistry. Especially the one-step conversion of ethene to propene (ETP reaction, 3C2H4 ® 2C3H6) is the most desired process. In our efforts, nickel
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Increased propene production is presently one of the most significant objectives in petroleum chemistry. Especially the one-step conversion of ethene to propene (ETP reaction, 3C2H4 ® 2C3H6) is the most desired process. In our efforts, nickel ion-loaded mesoporous silica could turn a new type of ETP reaction into reality. The one-step conversion of ethene was 68% and the propene selectivity was 48% in a continuous gas-flow system at 673 K and atmospheric pressure. The reactivity of lower olefins and the dependences of the ETP reaction on the contact time and the partial pressure of ethene were consistent with a reaction mechanism involving dimerization of ethene to 1-butene, isomerization of 1-butene to 2-butene, and metathesis of 2-butene and ethene to yield propene. The reaction was then expanded to an ethanol-to-propene reaction on the same catalyst, in which two possible reaction routes are suggested to form ethene from ethanol. The catalysts were characterized mainly by EXAFS and TPR techniques. The local structures of the nickel species active for the ETP reaction were very similar to that of layered nickel silicate, while those on the inert catalysts were the same as that of NiO particles.  Full article
(This article belongs to the Special Issue Olefin Metathesis and Its Application)
Open AccessReview Cardanol-Based Materials as Natural Precursors for Olefin Metathesis
Molecules 2011, 16(8), 6871-6882; doi:10.3390/molecules16086871
Received: 4 May 2011 / Revised: 8 July 2011 / Accepted: 12 July 2011 / Published: 11 August 2011
Cited by 27 | PDF Full-text (443 KB)
Abstract
Cardanol is a renewable, low cost natural material, widely available as a by-product of the cashew industry. It is a mixture of 3-n-pentadecylphenol, 3-(pentadeca-8-enyl)phenol, 3-(pentadeca-8,11-dienyl)phenol and 3-(pentadeca-8,11,14-trienyl)phenol. Olefin metathesis (OM) reaction on cardanol is an important class of reactions that allows
[...] Read more.
Cardanol is a renewable, low cost natural material, widely available as a by-product of the cashew industry. It is a mixture of 3-n-pentadecylphenol, 3-(pentadeca-8-enyl)phenol, 3-(pentadeca-8,11-dienyl)phenol and 3-(pentadeca-8,11,14-trienyl)phenol. Olefin metathesis (OM) reaction on cardanol is an important class of reactions that allows for the synthesis of new olefins that are sometime impossible to prepare via other methods. The application of this natural and renewable material to both academic and industrial research will be discussed. Full article
(This article belongs to the Special Issue Olefin Metathesis and Its Application)

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