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Robert H Grubbs - One of the best experts on this subject based on the ideXlab platform.
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recent advances in ruthenium based Olefin Metathesis
Chemical Society Reviews, 2018Co-Authors: O M Ogba, Daniel J Oleary, N C Warner, Robert H GrubbsAbstract:Ruthenium-based Olefin Metathesis catalysts, known for their functional group tolerance and broad applicability in organic synthesis and polymer science, continue to evolve as an enabling technology in these areas. A discussion of recent mechanistic investigations is followed by an overview of selected applications.
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an initiation kinetics prediction model enables rational design of ruthenium Olefin Metathesis catalysts bearing modified chelating benzylidenes
ACS Catalysis, 2018Co-Authors: Shao-xiong Luo, Peng Liu, Keary M. Engle, Xiaofei Dong, Andrew Hejl, Michael K. Takase, Lawrence M. Henling, K. N. Houk, Robert H GrubbsAbstract:Rational design of second-generation ruthenium Olefin Metathesis catalysts with desired initiation rates can be enabled by a computational model that is dependent on a single thermodynamic parameter. Using a computational model with no assumption about the specific initiation mechanism, the initiation kinetics of a spectrum of second-generation ruthenium Olefin Metathesis catalysts bearing modified chelating ortho-alkoxy benzylidenes were predicted in this work. Experimental tests of the validity of the computational model were achieved by the synthesis of a series of ruthenium Olefin Metathesis catalysts and investigation of initiation rates by ultraviolet–visible light (UV-vis) kinetics, nuclear magnetic resonance (NMR) spectroscopy, and structural characterization by X-ray crystallography. Included in this series of catalysts were 13 catalysts bearing alkoxy groups with varied steric bulk on the chelating benzylidene, ranging from ethoxy to dicyclohexylmethoxy groups. The experimentally observed initia...
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An Initiation Kinetics Prediction Model Enables Rational Design of Ruthenium Olefin Metathesis Catalysts Bearing Modified Chelating Benzylidenes
2018Co-Authors: Shao-xiong Luo, Peng Liu, Keary M. Engle, Xiaofei Dong, Andrew Hejl, Michael K. Takase, Lawrence M. Henling, K. N. Houk, Robert H GrubbsAbstract:Rational design of second-generation ruthenium Olefin Metathesis catalysts with desired initiation rates can be enabled by a computational model that is dependent on a single thermodynamic parameter. Using a computational model with no assumption about the specific initiation mechanism, the initiation kinetics of a spectrum of second-generation ruthenium Olefin Metathesis catalysts bearing modified chelating ortho-alkoxy benzylidenes were predicted in this work. Experimental tests of the validity of the computational model were achieved by the synthesis of a series of ruthenium Olefin Metathesis catalysts and investigation of initiation rates by ultraviolet–visible light (UV-vis) kinetics, nuclear magnetic resonance (NMR) spectroscopy, and structural characterization by X-ray crystallography. Included in this series of catalysts were 13 catalysts bearing alkoxy groups with varied steric bulk on the chelating benzylidene, ranging from ethoxy to dicyclohexylmethoxy groups. The experimentally observed initiation kinetics of the synthesized catalysts were in good accordance with computational predictions. Notably, the fast initiation rate of the dicyclohexylmethoxy catalyst was successfully predicted by the model, and this complex is believed to be among the fastest initiating Hoveyda–Grubbs-type catalysts reported to date. The compatibility of the predictive model with other catalyst families, including those bearing alternative N-heterocyclic carbene (NHC) ligands or disubstituted alkoxy benzylidenes, was also examined
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z selective Olefin Metathesis on peptides investigation of side chain influence preorganization and guidelines in substrate selection
Journal of the American Chemical Society, 2014Co-Authors: Shane L Mangold, Daniel J Oleary, Robert H GrubbsAbstract:Olefin Metathesis has emerged as a promising strategy for modulating the stability and activity of biologically relevant compounds; however, the ability to control Olefin geometry in the product remains a challenge. Recent advances in the design of cyclometalated ruthenium catalysts has led to new strategies for achieving such control with high fidelity and Z selectivity, but the scope and limitations of these catalysts on substrates bearing multiple functionalities, including peptides, remained unexplored. Herein, we report an assessment of various factors that contribute to both productive and nonproductive Z-selective Metathesis on peptides. The influence of sterics, side-chain identity, and preorganization through peptide secondary structure are explored by homodimerization, cross Metathesis, and ring-closing Metathesis. Our results indicate that the amino acid side chain and identity of the Olefin profoundly influence the activity of cyclometalated ruthenium catalysts in Z-selective Metathesis. The criteria set forth for achieving high conversion and Z selectivity are highlighted by cross Metathesis and ring-closing Metathesis on diverse peptide substrates. The principles outlined in this report are important not only for expanding the scope of Z-selective Olefin Metathesis to peptides but also for applying stereoselective Olefin Metathesis in general synthetic endeavors.
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alkene chemoselectivity in ruthenium catalyzed z selective Olefin Metathesis
Angewandte Chemie, 2013Co-Authors: Jeffrey S Cannon, Robert H GrubbsAbstract:Chelated ruthenium catalysts can facilitate highly chemoselective Olefin Metathesis. Terminal and internal Z Olefins reacted selectively to form new Z Olefins in the presence of internal E Olefins. Chemoselectivity for terminal Olefins was also observed over both sterically hindered and electronically deactivated alkenes.
Corinna S. Schindler - One of the best experts on this subject based on the ideXlab platform.
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catalytic carbonyl Olefin Metathesis of aliphatic ketones iron iii homo dimers as lewis acidic superelectrophiles
Journal of the American Chemical Society, 2019Co-Authors: Haley Albright, Jacob R Ludwig, Paul M. Zimmerman, Paul S Riehl, Christopher C Mcatee, Jolene P Reid, Lindsey A Karp, Matthew S Sigman, Corinna S. SchindlerAbstract:Catalytic carbonyl-Olefin Metathesis reactions have recently been developed as a powerful tool for carbon–carbon bond formation. However, currently available synthetic protocols rely exclusively on...
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interrupted carbonyl Olefin Metathesis via oxygen atom transfer
Science, 2018Co-Authors: Jacob R Ludwig, Joseph B Gianino, Paul M. Zimmerman, Rebecca B Watson, Daniel J Nasrallah, Ren A Wiscons, Corinna S. SchindlerAbstract:Some of the simplest and most powerful carbon-carbon bond forming strategies take advantage of readily accessible ubiquitous motifs: carbonyls and Olefins. Here we report a fundamentally distinct mode of reactivity between carbonyls and Olefins that differs from established acid-catalyzed carbonyl-ene, Prins, and carbonyl-Olefin Metathesis reaction paths. A range of epsilon, zeta-unsaturated ketones undergo Bronsted acid–catalyzed intramolecular cyclization to provide tetrahydrofluorene products via the formation of two new carbon-carbon bonds. Theoretical calculations and accompanying mechanistic studies suggest that this carbocyclization reaction proceeds through the intermediacy of a transient oxetane formed by oxygen atom transfer. The complex polycyclic frameworks in this product class appear as common substructures in organic materials, bioactive natural products, and recently developed pharmaceuticals.
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3‑Aryl-2,5-Dihydropyrroles via Catalytic Carbonyl-Olefin Metathesis
2018Co-Authors: Emilia J. Groso, Alexander N. Golonka, Ryan A. Harding, Brandon W. Alexander, Taylor M. Sodano, Corinna S. SchindlerAbstract:Herein, we describe the development of a synthetic strategy toward chiral 3-pyrrolines based on the design principle of iron(III)-catalyzed carbonyl-Olefin Metathesis. This approach takes advantage of commercially available amino acids as chiral pool reagents and FeCl3 as a Lewis acid catalyst. Our strategy is characterized by its operational simplicity, mild reaction conditions, and functional group tolerance. Investigations show that an electron-deficient nitrogen protecting group overcomes limitations arising from competitive binding of the Lewis acid catalyst to unfavorable Lewis basic sites, which ultimately enables catalytic turnover
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polycyclic aromatic hydrocarbons via iron iii catalyzed carbonyl Olefin Metathesis
Journal of the American Chemical Society, 2017Co-Authors: Christopher C Mcatee, Paul S Riehl, Corinna S. SchindlerAbstract:Polycyclic aromatic hydrocarbons are important structural motifs in organic chemistry, pharmaceutical chemistry, and materials science. The development of a new synthetic strategy toward these compounds is described based on the design principle of iron(III)-catalyzed carbonyl–Olefin Metathesis reactions. This approach is characterized by its operational simplicity, high functional group compatibility, and regioselectivity while relying on FeCl3 as an environmentally benign, earth-abundant metal catalyst. Experimental evidence for oxetanes as reactive intermediates in the catalytic carbonyl–Olefin ring-closing Metathesis has been obtained.
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iron iii catalysed carbonyl Olefin Metathesis
Nature, 2016Co-Authors: Jacob R Ludwig, Joseph B Gianino, Paul M. Zimmerman, Corinna S. SchindlerAbstract:The Olefin Metathesis reaction of two unsaturated substrates is one of the most powerful carbon–carbon-bond-forming reactions in organic chemistry; here, a catalytic carbonyl–Olefin ring-closing Metathesis reaction is demonstrated that uses iron, an abundant and environmentally benign metal, as a catalyst. The carbonyl–Olefin Metathesis reaction, like the well established Olefin Metathesis reaction, can be used to construct carbon–carbon bonds. However, currently available methods for the carbonyl–Olefin variant of the reaction have practical limitations. These authors demonstrate a catalytic carbonyl–Olefin ring-closing Metathesis reaction that uses iron — a cheap, plentiful and environmentally benign transition metal — as a catalyst. This transformation accommodates a variety of substrates and is distinguished by its operational simplicity, mild reaction conditions, high functional-group tolerance, and amenability to gram-scale synthesis. The Olefin Metathesis reaction of two unsaturated substrates is one of the most powerful carbon–carbon-bond-forming reactions in organic chemistry. Specifically, the catalytic Olefin Metathesis reaction has led to profound developments in the synthesis of molecules relevant to the petroleum, materials, agricultural and pharmaceutical industries1. These reactions are characterized by their use of discrete metal alkylidene catalysts that operate via a well-established mechanism2. While the corresponding carbonyl–Olefin Metathesis reaction can also be used to construct carbon–carbon bonds, currently available methods are scarce and severely hampered by either harsh reaction conditions or the required use of stoichiometric transition metals as reagents. To date, no general protocol for catalytic carbonyl–Olefin Metathesis has been reported. Here we demonstrate a catalytic carbonyl–Olefin ring-closing Metathesis reaction that uses iron, an Earth-abundant and environmentally benign transition metal, as a catalyst. This transformation accommodates a variety of substrates and is distinguished by its operational simplicity, mild reaction conditions, high functional-group tolerance, and amenability to gram-scale synthesis. We anticipate that these characteristics, coupled with the efficiency of this reaction, will allow for further advances in areas that have historically been enhanced by Olefin Metathesis.
Tristan H Lambert - One of the best experts on this subject based on the ideXlab platform.
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synthesis of 2h chromenes via hydrazine catalyzed ring closing carbonyl Olefin Metathesis
ACS Catalysis, 2019Co-Authors: Yunfei Zhang, Janis Jermaks, Samantha N Macmillan, Tristan H LambertAbstract:The catalytic ring-closing carbonyl-Olefin Metathesis (RCCOM) of O-allyl salicylaldehydes to form 2H-chromenes is described. The method utilizes a [2.2.1]-bicyclic hydrazine catalyst and operates v...
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organocatalytic carbonyl Olefin Metathesis
Journal of the American Chemical Society, 2012Co-Authors: Allison K Griffith, Christine M Vanos, Tristan H LambertAbstract:The development of a catalytic carbonyl-Olefin Metathesis strategy is reported, in the context of the ring-opening Metathesis of cyclopropenes with aldehydes using a simple hydrazine catalyst. The key to this reaction is a conceptual blueprint for Metathesis chemistry that forgoes the traditional reliance on [2 + 2] cycloaddition modes in favor of a [3 + 2] paradigm.
Jacob R Ludwig - One of the best experts on this subject based on the ideXlab platform.
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catalytic carbonyl Olefin Metathesis of aliphatic ketones iron iii homo dimers as lewis acidic superelectrophiles
Journal of the American Chemical Society, 2019Co-Authors: Haley Albright, Jacob R Ludwig, Paul M. Zimmerman, Paul S Riehl, Christopher C Mcatee, Jolene P Reid, Lindsey A Karp, Matthew S Sigman, Corinna S. SchindlerAbstract:Catalytic carbonyl-Olefin Metathesis reactions have recently been developed as a powerful tool for carbon–carbon bond formation. However, currently available synthetic protocols rely exclusively on...
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interrupted carbonyl Olefin Metathesis via oxygen atom transfer
Science, 2018Co-Authors: Jacob R Ludwig, Joseph B Gianino, Paul M. Zimmerman, Rebecca B Watson, Daniel J Nasrallah, Ren A Wiscons, Corinna S. SchindlerAbstract:Some of the simplest and most powerful carbon-carbon bond forming strategies take advantage of readily accessible ubiquitous motifs: carbonyls and Olefins. Here we report a fundamentally distinct mode of reactivity between carbonyls and Olefins that differs from established acid-catalyzed carbonyl-ene, Prins, and carbonyl-Olefin Metathesis reaction paths. A range of epsilon, zeta-unsaturated ketones undergo Bronsted acid–catalyzed intramolecular cyclization to provide tetrahydrofluorene products via the formation of two new carbon-carbon bonds. Theoretical calculations and accompanying mechanistic studies suggest that this carbocyclization reaction proceeds through the intermediacy of a transient oxetane formed by oxygen atom transfer. The complex polycyclic frameworks in this product class appear as common substructures in organic materials, bioactive natural products, and recently developed pharmaceuticals.
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iron iii catalysed carbonyl Olefin Metathesis
Nature, 2016Co-Authors: Jacob R Ludwig, Joseph B Gianino, Paul M. Zimmerman, Corinna S. SchindlerAbstract:The Olefin Metathesis reaction of two unsaturated substrates is one of the most powerful carbon–carbon-bond-forming reactions in organic chemistry; here, a catalytic carbonyl–Olefin ring-closing Metathesis reaction is demonstrated that uses iron, an abundant and environmentally benign metal, as a catalyst. The carbonyl–Olefin Metathesis reaction, like the well established Olefin Metathesis reaction, can be used to construct carbon–carbon bonds. However, currently available methods for the carbonyl–Olefin variant of the reaction have practical limitations. These authors demonstrate a catalytic carbonyl–Olefin ring-closing Metathesis reaction that uses iron — a cheap, plentiful and environmentally benign transition metal — as a catalyst. This transformation accommodates a variety of substrates and is distinguished by its operational simplicity, mild reaction conditions, high functional-group tolerance, and amenability to gram-scale synthesis. The Olefin Metathesis reaction of two unsaturated substrates is one of the most powerful carbon–carbon-bond-forming reactions in organic chemistry. Specifically, the catalytic Olefin Metathesis reaction has led to profound developments in the synthesis of molecules relevant to the petroleum, materials, agricultural and pharmaceutical industries1. These reactions are characterized by their use of discrete metal alkylidene catalysts that operate via a well-established mechanism2. While the corresponding carbonyl–Olefin Metathesis reaction can also be used to construct carbon–carbon bonds, currently available methods are scarce and severely hampered by either harsh reaction conditions or the required use of stoichiometric transition metals as reagents. To date, no general protocol for catalytic carbonyl–Olefin Metathesis has been reported. Here we demonstrate a catalytic carbonyl–Olefin ring-closing Metathesis reaction that uses iron, an Earth-abundant and environmentally benign transition metal, as a catalyst. This transformation accommodates a variety of substrates and is distinguished by its operational simplicity, mild reaction conditions, high functional-group tolerance, and amenability to gram-scale synthesis. We anticipate that these characteristics, coupled with the efficiency of this reaction, will allow for further advances in areas that have historically been enhanced by Olefin Metathesis.
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iron iii catalysed carbonyl Olefin Metathesis
Nature, 2016Co-Authors: Jacob R Ludwig, Joseph B Gianino, Paul M. Zimmerman, Corinna S. SchindlerAbstract:The Olefin Metathesis reaction of two unsaturated substrates is one of the most powerful carbon-carbon-bond-forming reactions in organic chemistry. Specifically, the catalytic Olefin Metathesis reaction has led to profound developments in the synthesis of molecules relevant to the petroleum, materials, agricultural and pharmaceutical industries. These reactions are characterized by their use of discrete metal alkylidene catalysts that operate via a well-established mechanism. While the corresponding carbonyl-Olefin Metathesis reaction can also be used to construct carbon-carbon bonds, currently available methods are scarce and severely hampered by either harsh reaction conditions or the required use of stoichiometric transition metals as reagents. To date, no general protocol for catalytic carbonyl-Olefin Metathesis has been reported. Here we demonstrate a catalytic carbonyl-Olefin ring-closing Metathesis reaction that uses iron, an Earth-abundant and environmentally benign transition metal, as a catalyst. This transformation accommodates a variety of substrates and is distinguished by its operational simplicity, mild reaction conditions, high functional-group tolerance, and amenability to gram-scale synthesis. We anticipate that these characteristics, coupled with the efficiency of this reaction, will allow for further advances in areas that have historically been enhanced by Olefin Metathesis.
Paul M. Zimmerman - One of the best experts on this subject based on the ideXlab platform.
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catalytic carbonyl Olefin Metathesis of aliphatic ketones iron iii homo dimers as lewis acidic superelectrophiles
Journal of the American Chemical Society, 2019Co-Authors: Haley Albright, Jacob R Ludwig, Paul M. Zimmerman, Paul S Riehl, Christopher C Mcatee, Jolene P Reid, Lindsey A Karp, Matthew S Sigman, Corinna S. SchindlerAbstract:Catalytic carbonyl-Olefin Metathesis reactions have recently been developed as a powerful tool for carbon–carbon bond formation. However, currently available synthetic protocols rely exclusively on...
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interrupted carbonyl Olefin Metathesis via oxygen atom transfer
Science, 2018Co-Authors: Jacob R Ludwig, Joseph B Gianino, Paul M. Zimmerman, Rebecca B Watson, Daniel J Nasrallah, Ren A Wiscons, Corinna S. SchindlerAbstract:Some of the simplest and most powerful carbon-carbon bond forming strategies take advantage of readily accessible ubiquitous motifs: carbonyls and Olefins. Here we report a fundamentally distinct mode of reactivity between carbonyls and Olefins that differs from established acid-catalyzed carbonyl-ene, Prins, and carbonyl-Olefin Metathesis reaction paths. A range of epsilon, zeta-unsaturated ketones undergo Bronsted acid–catalyzed intramolecular cyclization to provide tetrahydrofluorene products via the formation of two new carbon-carbon bonds. Theoretical calculations and accompanying mechanistic studies suggest that this carbocyclization reaction proceeds through the intermediacy of a transient oxetane formed by oxygen atom transfer. The complex polycyclic frameworks in this product class appear as common substructures in organic materials, bioactive natural products, and recently developed pharmaceuticals.
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iron iii catalysed carbonyl Olefin Metathesis
Nature, 2016Co-Authors: Jacob R Ludwig, Joseph B Gianino, Paul M. Zimmerman, Corinna S. SchindlerAbstract:The Olefin Metathesis reaction of two unsaturated substrates is one of the most powerful carbon–carbon-bond-forming reactions in organic chemistry; here, a catalytic carbonyl–Olefin ring-closing Metathesis reaction is demonstrated that uses iron, an abundant and environmentally benign metal, as a catalyst. The carbonyl–Olefin Metathesis reaction, like the well established Olefin Metathesis reaction, can be used to construct carbon–carbon bonds. However, currently available methods for the carbonyl–Olefin variant of the reaction have practical limitations. These authors demonstrate a catalytic carbonyl–Olefin ring-closing Metathesis reaction that uses iron — a cheap, plentiful and environmentally benign transition metal — as a catalyst. This transformation accommodates a variety of substrates and is distinguished by its operational simplicity, mild reaction conditions, high functional-group tolerance, and amenability to gram-scale synthesis. The Olefin Metathesis reaction of two unsaturated substrates is one of the most powerful carbon–carbon-bond-forming reactions in organic chemistry. Specifically, the catalytic Olefin Metathesis reaction has led to profound developments in the synthesis of molecules relevant to the petroleum, materials, agricultural and pharmaceutical industries1. These reactions are characterized by their use of discrete metal alkylidene catalysts that operate via a well-established mechanism2. While the corresponding carbonyl–Olefin Metathesis reaction can also be used to construct carbon–carbon bonds, currently available methods are scarce and severely hampered by either harsh reaction conditions or the required use of stoichiometric transition metals as reagents. To date, no general protocol for catalytic carbonyl–Olefin Metathesis has been reported. Here we demonstrate a catalytic carbonyl–Olefin ring-closing Metathesis reaction that uses iron, an Earth-abundant and environmentally benign transition metal, as a catalyst. This transformation accommodates a variety of substrates and is distinguished by its operational simplicity, mild reaction conditions, high functional-group tolerance, and amenability to gram-scale synthesis. We anticipate that these characteristics, coupled with the efficiency of this reaction, will allow for further advances in areas that have historically been enhanced by Olefin Metathesis.
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iron iii catalysed carbonyl Olefin Metathesis
Nature, 2016Co-Authors: Jacob R Ludwig, Joseph B Gianino, Paul M. Zimmerman, Corinna S. SchindlerAbstract:The Olefin Metathesis reaction of two unsaturated substrates is one of the most powerful carbon-carbon-bond-forming reactions in organic chemistry. Specifically, the catalytic Olefin Metathesis reaction has led to profound developments in the synthesis of molecules relevant to the petroleum, materials, agricultural and pharmaceutical industries. These reactions are characterized by their use of discrete metal alkylidene catalysts that operate via a well-established mechanism. While the corresponding carbonyl-Olefin Metathesis reaction can also be used to construct carbon-carbon bonds, currently available methods are scarce and severely hampered by either harsh reaction conditions or the required use of stoichiometric transition metals as reagents. To date, no general protocol for catalytic carbonyl-Olefin Metathesis has been reported. Here we demonstrate a catalytic carbonyl-Olefin ring-closing Metathesis reaction that uses iron, an Earth-abundant and environmentally benign transition metal, as a catalyst. This transformation accommodates a variety of substrates and is distinguished by its operational simplicity, mild reaction conditions, high functional-group tolerance, and amenability to gram-scale synthesis. We anticipate that these characteristics, coupled with the efficiency of this reaction, will allow for further advances in areas that have historically been enhanced by Olefin Metathesis.
