Stereoretentive Olefin Metathesis: A New Avenue for the Synthesis of All-cis Poly(p-phenylene vinylene)s and Stereo­defined Polyalkenamers

Synlett ◽  
2021 ◽  
Author(s):  
Quentin Michaudel ◽  
Samuel J. Kempel ◽  
Ting-Wei Hsu
Keyword(s):  
Olefin Metathesis ◽  
Ring Opening ◽  
Diblock Copolymers ◽  
Catalyst Design ◽  
Phenylene Vinylene ◽  
Grand Challenge ◽  
Ru Catalyst ◽  
Unique Reaction ◽  
Photochemical Isomerization ◽  
Optimized Conditions

AbstractOlefin metathesis has tremendously impacted all fields of synthetic chemistry. However, the control of the olefin stereochemistry during this process remains a grand challenge. Recent innovations in catalyst design have permitted control of the stereochemistry of the olefin product. Here, we discuss the development of stereoretentive olefin metathesis, with an emphasis on the synthesis of stereodefined polyalkenamers through ring-opening metathesis polymerization (ROMP). We then present our application of this unique reaction manifold to the preparation of all-cis poly(p-phenylene vinylene)s (PPVs). A dithiolate Ru catalyst was found to deliver perfect cis selectivity for the polymerization of a paracyclophane diene monomer. By using optimized conditions, all-cis PPVs with narrow dispersities and predictable molar masses were obtained by varying the ratio of monomer to catalyst. The high chain fidelity of the stereoretentive ROMP with a paracyclophane diene monomer enabled the preparation of well-defined diblock copolymers with a norbornene co-monomer. Photochemical isomerization of all-cis to all-trans PPVs was effected with both homopolymers and diblock copolymers. This process was shown to be selective for the PPV block, and resulted in changes in optical properties, polymer size, and solubility. Stereoretentive ROMP provides a promising platform for synthesizing polymers with unique properties, including photoresponsive all-cis PPVs with living characteristics.1 Introduction2 Synthetic Applications of Stereoretentive Olefin Metathesis3 Stereocontrol of Polyalkenamers through Stereoretentive ROMP4 Stereoretentive ROMP To Access All-cis Poly(p-phenylene vinylene)s5 Conclusion

scholarly journals Ring-Opening Carbonyl-Olefin Metathesis of Norbornenes

2019 ◽  
Author(s):  
Janis Jermaks ◽  
Phong K. Quach ◽  
Zara M. Seibel ◽  
Julien Pomarole ◽  
Tristan Lambert
Keyword(s):  
Experimental Study ◽  
Theoretical Investigation ◽  
Olefin Metathesis ◽  
Ring Opening ◽  
Activation Barrier ◽  
Reaction Pathway ◽  
Next Generation ◽  
Methyl Group ◽  
Optimized Conditions ◽  
Hydrolysis Of

<div> <p>A computational and experimental study of the hydrazine-catalyzed ring-opening carbonyl-olefin metathesis of norbornenes is described. Detailed theoretical investigation of the energetic landscape for the full reaction pathway with six different hydrazines revealed several crucial aspects for the design of next-generation hydrazine catalysts. This study indicated that a [2.2.2]-bicyclic hydrazine should offer substantially increased reactivity versus the previously reported [2.2.1]-hydrazine due to a lowered activation barrier for the rate-determining cycloreversion step, a prediction which was verified experimentally. Optimized conditions for both cycloaddition and cycloreversion steps were identified, and a brief substrate scope study for each was conducted. A complication for catalysis was found to be the slow hydrolysis of the ring-opened hydrazonium intermediates, which were shown to suffer from a competitive and irreversible cycloaddition with a second equivalent of norbornene. This problem was overcome by the strategic incorporation of a bridgehead methyl group on the norbornene ring, leading to the first demonstrated catalytic carbonyl-olefin metathesis of norbornene rings.</p> </div>

scholarly journals Catalytic, Transannular Carbonyl-Olefin Metathesis Reactions

2019 ◽  
Author(s):  
Paul Riehl ◽  
Daniel Nasrallah ◽  
Corinna Schindler
Keyword(s):  
Lewis Acid ◽  
Olefin Metathesis ◽  
Ring Opening ◽  
Acid Catalyst ◽  
Catalyst Design ◽  
Lewis Acid Catalysts ◽  
Complex Molecules ◽  
New Class ◽  
Metathesis Reactions ◽  
Lewis Acid Catalyst

A new class of Lewis acid-catalyzed carbonyl-olefin metathesis reactions is described that complements existing protocols for related ring-closing, ring-opening, and intermolecular transformations. These transannular carbonyl-olefin metathesis reactions rely on FeCl<sub>3</sub> as an inexpensive Lewis acid catalyst and are mechanistically distinct from previously developed protocols for ring closing, ring-opening and intermolecular metathesis. Specifically, carbonyl-ene and carbonyl-olefin metathesis reaction paths are competing to ultimately favor metathesis as the thermodynamic product. Importantly, we show that distinct Lewis acid catalysts are able to differentiate between these pathways to enable the selective formation of transannular carbonyl-ene or carbonyl-olefin metathesis products thus providing a valuable approach to the molecular editing of naturally occurring complex molecules. Additionally, these results are expected to enable further advances in catalyst design for carbonyl-olefin metathesis to ultimately develop efficient and high-yielding catalytic carbonyl olefination reactions.

scholarly journals Catalytic, Transannular Carbonyl-Olefin Metathesis Reactions

2019 ◽  
Author(s):  
Paul Riehl ◽  
Daniel Nasrallah ◽  
Corinna Schindler
Keyword(s):  
Lewis Acid ◽  
Olefin Metathesis ◽  
Ring Opening ◽  
Acid Catalyst ◽  
Catalyst Design ◽  
Lewis Acid Catalysts ◽  
Complex Molecules ◽  
New Class ◽  
Metathesis Reactions ◽  
Lewis Acid Catalyst

A new class of Lewis acid-catalyzed carbonyl-olefin metathesis reactions is described that complements existing protocols for related ring-closing, ring-opening, and intermolecular transformations. These transannular carbonyl-olefin metathesis reactions rely on FeCl<sub>3</sub> as an inexpensive Lewis acid catalyst and are mechanistically distinct from previously developed protocols for ring closing, ring-opening and intermolecular metathesis. Specifically, carbonyl-ene and carbonyl-olefin metathesis reaction paths are competing to ultimately favor metathesis as the thermodynamic product. Importantly, we show that distinct Lewis acid catalysts are able to differentiate between these pathways to enable the selective formation of transannular carbonyl-ene or carbonyl-olefin metathesis products thus providing a valuable approach to the molecular editing of naturally occurring complex molecules. Additionally, these results are expected to enable further advances in catalyst design for carbonyl-olefin metathesis to ultimately develop efficient and high-yielding catalytic carbonyl olefination reactions.

Enhancement of ruthenium-catalyzed olefin metathesis reactions: Searching for new catalyst or new reaction conditions?

2011 ◽  
Vol 83 (3) ◽  
pp. 553-563 ◽  
Author(s):  
Anna Szadkowska ◽  
Cezary Samojłowicz ◽  
Karol Grela
Keyword(s):  
Olefin Metathesis ◽  
Industrial Process ◽  
Catalyst Design ◽  
Chemical Transformations ◽  
Metathesis Reaction ◽  
Reaction Conditions ◽  
Efficient Tool ◽  
Complex Molecules ◽  
Unique Reaction ◽  
Selection Of

Olefin metathesis as a catalytic process constantly gains interest among organic chemists. Over the last decade, it became an efficient tool to accomplish the synthesis of many complex molecules. The development of new well-defined catalysts and continuous examination of novel ligands led to the establishment of metathesis methodology in a group of widespread chemical transformations. Not only does the selection of the catalyst seem to be of crucial importance, but modifying the reaction conditions, such as choice of the solvent and temperature, also allows one to make olefin metathesis a practical industrial process. This contribution, based on examples from our research, is devoted to answering the question “What may have a greater impact on the performance of metathesis reaction: a sophisticated catalyst design or unique reaction conditions?” Based on the data reported in the paper, we discuss two complementary strategies concerning the tuning of the olefin metathesis process.

scholarly journals Catalytic, Transannular Carbonyl-Olefin Metathesis Reactions

2019 ◽  
Author(s):  
Paul Riehl ◽  
Daniel Nasrallah ◽  
Corinna Schindler
Keyword(s):  
Lewis Acid ◽  
Olefin Metathesis ◽  
Ring Opening ◽  
Acid Catalyst ◽  
Catalyst Design ◽  
Lewis Acid Catalysts ◽  
Complex Molecules ◽  
New Class ◽  
Metathesis Reactions ◽  
Lewis Acid Catalyst

A new class of Lewis acid-catalyzed carbonyl-olefin metathesis reactions is described that complements existing protocols for related ring-closing, ring-opening, and intermolecular transformations. These transannular carbonyl-olefin metathesis reactions rely on FeCl<sub>3</sub> as an inexpensive Lewis acid catalyst and are mechanistically distinct from previously developed protocols for ring closing, ring-opening and intermolecular metathesis. Specifically, carbonyl-ene and carbonyl-olefin metathesis reaction paths are competing to ultimately favor metathesis as the thermodynamic product. Importantly, we show that distinct Lewis acid catalysts are able to differentiate between these pathways to enable the selective formation of transannular carbonyl-ene or carbonyl-olefin metathesis products thus providing a valuable approach to the molecular editing of naturally occurring complex molecules. Additionally, these results are expected to enable further advances in catalyst design for carbonyl-olefin metathesis to ultimately develop efficient and high-yielding catalytic carbonyl olefination reactions.

Stereoretentive Ring-Opening Metathesis Polymerization to Access All-cis Poly(p-phenylene vinylene)s with Living Characteristics

2020 ◽  
Author(s):  
Ting-Wei Hsu ◽  
Cheoljae Kim ◽  
Quentin Michaudel
Keyword(s):  
Organic Material ◽  
Ring Opening ◽  
Diblock Copolymers ◽  
Conductive Polymer ◽  
Synthetic Methods ◽  
Phenylene Vinylene ◽  
Ring Opening Metathesis Polymerization ◽  
Metathesis Polymerization ◽  
Molecular Weights ◽  
Responsive Polymers

Poly(p-phenylene vinylene)s (PPVs), a staple of the conductive polymer family, consist of alternating alkene and phenyl groups in conjugation. The physical properties of this organic material are intimately linked to the cis/trans configuration of the alkene groups. While many synthetic methods afford PPVs with alltrans stereochemistry, very few deliver the all-cis congeners. We report herein the first synthesis of all-cis PPVs with living characteristics via stereoretentive ring-opening metathesis polymerization (ROMP). Exquisite catalyst control allows for the preparation of homopolymers or diblock copolymers with perfect stereoselectivity, narrow dispersities, and predictable molecular weights. All-cis PPVs can then serve as light-responsive polymers through clean photoisomerization of the stilbenoid units.

Stereoretentive Ring-Opening Metathesis Polymerization to Access All-cis Poly(p-phenylene vinylene)s with Living Characteristics

2020 ◽  
Author(s):  
Ting-Wei Hsu ◽  
Cheoljae Kim ◽  
Quentin Michaudel
Keyword(s):  
Organic Material ◽  
Ring Opening ◽  
Diblock Copolymers ◽  
Conductive Polymer ◽  
Synthetic Methods ◽  
Phenylene Vinylene ◽  
Ring Opening Metathesis Polymerization ◽  
Metathesis Polymerization ◽  
Molecular Weights ◽  
Responsive Polymers

Poly(p-phenylene vinylene)s (PPVs), a staple of the conductive polymer family, consist of alternating alkene and phenyl groups in conjugation. The physical properties of this organic material are intimately linked to the cis/trans configuration of the alkene groups. While many synthetic methods afford PPVs with alltrans stereochemistry, very few deliver the all-cis congeners. We report herein the first synthesis of all-cis PPVs with living characteristics via stereoretentive ring-opening metathesis polymerization (ROMP). Exquisite catalyst control allows for the preparation of homopolymers or diblock copolymers with perfect stereoselectivity, narrow dispersities, and predictable molecular weights. All-cis PPVs can then serve as light-responsive polymers through clean photoisomerization of the stilbenoid units.

scholarly journals Ring-Opening Carbonyl-Olefin Metathesis of Norbornenes

2019 ◽  
Author(s):  
Janis Jermaks ◽  
Phong K. Quach ◽  
Zara M. Seibel ◽  
Julien Pomarole ◽  
Tristan Lambert
Keyword(s):  
Experimental Study ◽  
Theoretical Investigation ◽  
Olefin Metathesis ◽  
Ring Opening ◽  
Activation Barrier ◽  
Reaction Pathway ◽  
Next Generation ◽  
Methyl Group ◽  
Optimized Conditions ◽  
Hydrolysis Of

<div> <p>A computational and experimental study of the hydrazine-catalyzed ring-opening carbonyl-olefin metathesis of norbornenes is described. Detailed theoretical investigation of the energetic landscape for the full reaction pathway with six different hydrazines revealed several crucial aspects for the design of next-generation hydrazine catalysts. This study indicated that a [2.2.2]-bicyclic hydrazine should offer substantially increased reactivity versus the previously reported [2.2.1]-hydrazine due to a lowered activation barrier for the rate-determining cycloreversion step, a prediction which was verified experimentally. Optimized conditions for both cycloaddition and cycloreversion steps were identified, and a brief substrate scope study for each was conducted. A complication for catalysis was found to be the slow hydrolysis of the ring-opened hydrazonium intermediates, which were shown to suffer from a competitive and irreversible cycloaddition with a second equivalent of norbornene. This problem was overcome by the strategic incorporation of a bridgehead methyl group on the norbornene ring, leading to the first demonstrated catalytic carbonyl-olefin metathesis of norbornene rings.</p> </div>

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