The Experts below are selected from a list of 192 Experts worldwide ranked by ideXlab platform
Mingzhong Cai - One of the best experts on this subject based on the ideXlab platform.
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One-Pot, Stereoselective Synthesis of Trisubstituted 1,3-Dienes by Hydromagnesiation-Cross-Coupling Tandem Reaction of Alkylarylacetylenes with Alkenyl Iodides.
ChemInform, 2012Co-Authors: Pingping Wang, Haiyun Zhang, Mingzhong CaiAbstract:The procedure is described as applicable to the stereocontrolled synthesis of naturally occurring 1,3-diene systems.
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One-Pot, Stereoselective Synthesis of Trisubstituted 1,3-Dienes by Hydromagnesiation–Cross-Coupling Tandem Reaction of Alkylarylacetylenes with Alkenyl Iodides
Synthetic Communications, 2011Co-Authors: Pingping Wang, Haiyun Zhang, Mingzhong CaiAbstract:Abstract Trisubstituted 1,3-dienes can be stereoselectively synthesized in one pot under mild conditions, in good yields, by Hydromagnesiation of alkylarylacetylenes, followed by the palladium-catalyzed cross-coupling with alkenyl iodides.
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one pot stereoselective synthesis of trisubstituted 1 3 dienes by Hydromagnesiation cross coupling tandem reaction of alkylarylacetylenes with alkenyl iodides
Synthetic Communications, 2011Co-Authors: Pingping Wang, Haiyun Zhang, Mingzhong CaiAbstract:Abstract Trisubstituted 1,3-dienes can be stereoselectively synthesized in one pot under mild conditions, in good yields, by Hydromagnesiation of alkylarylacetylenes, followed by the palladium-catalyzed cross-coupling with alkenyl iodides.
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Stereoselective synthesis of difunctionalised 1,3-dienes containing silicon and sulfur via palladium catalysed cross-coupling reactions
Journal of Chemical Research, 2008Co-Authors: Haiyun Zhang, Mingzhong CaiAbstract:Hydromagnesiation of alkynylsilanes 1 in diethyl ether gave (Z)-α-silylvinyl Grignard reagents 2, which underwent a cross-coupling reaction with (E)-α-iodovinyl sulfides 3 in the presence of Pd(PPh 3 ) 4 as catalyst to afford stereoselectively (Z,Z)-2-silyl-3-arylsulfanyl-substituted 1,3-dienes 4 in good yields.
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novel stereoselective synthesis of e β silylvinylstannanes via Hydromagnesiation of silylarylacetylenes
Chinese Journal of Chemistry, 2006Co-Authors: Bin Huang, Zhou Zhou, Mingzhong CaiAbstract:Hydromagnesiation of silylarylacetylenes 1 in diethyl ether gave (E)-β-silylvinyl Grignard reagents 2, which reacted with trialkylstannyl chlorides 3 to afford stereoselectively (E)-β-silylvinylstannanes 4 in good yields.
Stephen P. Thomas - One of the best experts on this subject based on the ideXlab platform.
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tmeda in iron catalyzed Hydromagnesiation formation of iron ii alkyl species for controlled reduction to alkene stabilized iron 0
Angewandte Chemie, 2020Co-Authors: Peter G. N. Neate, Mark D. Greenhalgh, William W. Brennessel, Stephen P. Thomas, Michael L. NeidigAbstract:N,N,N',N'-Tetramethylethylenediamine (TMEDA) has been one of the most prevalent and successful additives used in iron catalysis, finding application in reactions as diverse as cross-coupling, C-H activation, and borylation. However, the role that TMEDA plays in these reactions remains largely undefined. Herein, studying the iron-catalyzed Hydromagnesiation of styrene derivatives using TMEDA has provided molecular-level insight into the role of TMEDA in achieving effective catalysis. The key is the initial formation of TMEDA-iron(II)-alkyl species which undergo a controlled reduction to selectively form catalytically active styrene-stabilized iron(0)-alkyl complexes. While TMEDA is not bound to the catalytically active species, these active iron(0) complexes cannot be accessed in the absence of TMEDA. This mode of action, allowing for controlled reduction and access to iron(0) species, represents a new paradigm for the role of this important reaction additive in iron catalysis.
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TMEDA in Iron‐Catalyzed Hydromagnesiation: Formation of Iron(II)‐Alkyl Species for Controlled Reduction to Alkene‐Stabilized Iron(0)
Angewandte Chemie (International ed. in English), 2020Co-Authors: Peter G. N. Neate, Mark D. Greenhalgh, William W. Brennessel, Stephen P. Thomas, Michael L. NeidigAbstract:N,N,N',N'-Tetramethylethylenediamine (TMEDA) has been one of the most prevalent and successful additives used in iron catalysis, finding application in reactions as diverse as cross-coupling, C-H activation, and borylation. However, the role that TMEDA plays in these reactions remains largely undefined. Herein, studying the iron-catalyzed Hydromagnesiation of styrene derivatives using TMEDA has provided molecular-level insight into the role of TMEDA in achieving effective catalysis. The key is the initial formation of TMEDA-iron(II)-alkyl species which undergo a controlled reduction to selectively form catalytically active styrene-stabilized iron(0)-alkyl complexes. While TMEDA is not bound to the catalytically active species, these active iron(0) complexes cannot be accessed in the absence of TMEDA. This mode of action, allowing for controlled reduction and access to iron(0) species, represents a new paradigm for the role of this important reaction additive in iron catalysis.
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Mechanism of the Bis(imino)pyridine-Iron-Catalyzed Hydromagnesiation of Styrene Derivatives.
Journal of the American Chemical Society, 2019Co-Authors: Peter G. N. Neate, Mark D. Greenhalgh, William W. Brennessel, Stephen P. Thomas, Michael L. NeidigAbstract:Iron-catalyzed Hydromagnesiation of styrene derivatives offers a rapid and efficient method to generate benzylic Grignard reagents, which can be applied in a range of transformations to provide products of formal hydrofunctionalization. While iron-catalyzed methodologies exist for the Hydromagnesiation of terminal alkenes, internal alkynes, and styrene derivatives, the underlying mechanisms of catalysis remain largely undefined. To address this issue and determine the divergent reactivity from established cross-coupling and hydrofunctionalization reactions, a detailed study of the bis(imino)pyridine iron-catalyzed Hydromagnesiation of styrene derivatives is reported. Using a combination of kinetic analysis, deuterium labeling, and reactivity studies as well as in situ 57Fe Mossbauer spectroscopy, key mechanistic features and species were established. A formally iron(0) ate complex [ iPrBIPFe(Et)(CH2═CH2)]- was identified as the principle resting state of the catalyst. Dissociation of ethene forms the catalytically active species which can reversibly coordinate the styrene derivative and mediate a direct and reversible β-hydride transfer, negating the necessity of a discrete iron hydride intermediate. Finally, displacement of the tridentate bis(imino)pyridine ligand over the course of the reaction results in the formation of a tris-styrene-coordinated iron(0) complex, which is also a competent catalyst for Hydromagnesiation.
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Broad Scope Hydrofunctionalization of Styrene Derivatives Using Iron‐Catalyzed Hydromagnesiation.
ChemInform, 2015Co-Authors: Alison S. Jones, Mark D. Greenhalgh, James F. Paliga, Jacob M. Quibell, Alan Steven, Stephen P. ThomasAbstract:An operationally simple, chemo- and regioselective Hydromagnesiation reaction generates benzylic Grignard reagents.
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broad scope hydrofunctionalization of styrene derivatives using iron catalyzed Hydromagnesiation
ChemInform, 2015Co-Authors: Alison S. Jones, Mark D. Greenhalgh, James F. Paliga, Jacob M. Quibell, Alan Steven, Stephen P. ThomasAbstract:An operationally simple, chemo- and regioselective Hydromagnesiation reaction generates benzylic Grignard reagents.
Mark D. Greenhalgh - One of the best experts on this subject based on the ideXlab platform.
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tmeda in iron catalyzed Hydromagnesiation formation of iron ii alkyl species for controlled reduction to alkene stabilized iron 0
Angewandte Chemie, 2020Co-Authors: Peter G. N. Neate, Mark D. Greenhalgh, William W. Brennessel, Stephen P. Thomas, Michael L. NeidigAbstract:N,N,N',N'-Tetramethylethylenediamine (TMEDA) has been one of the most prevalent and successful additives used in iron catalysis, finding application in reactions as diverse as cross-coupling, C-H activation, and borylation. However, the role that TMEDA plays in these reactions remains largely undefined. Herein, studying the iron-catalyzed Hydromagnesiation of styrene derivatives using TMEDA has provided molecular-level insight into the role of TMEDA in achieving effective catalysis. The key is the initial formation of TMEDA-iron(II)-alkyl species which undergo a controlled reduction to selectively form catalytically active styrene-stabilized iron(0)-alkyl complexes. While TMEDA is not bound to the catalytically active species, these active iron(0) complexes cannot be accessed in the absence of TMEDA. This mode of action, allowing for controlled reduction and access to iron(0) species, represents a new paradigm for the role of this important reaction additive in iron catalysis.
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TMEDA in Iron‐Catalyzed Hydromagnesiation: Formation of Iron(II)‐Alkyl Species for Controlled Reduction to Alkene‐Stabilized Iron(0)
Angewandte Chemie (International ed. in English), 2020Co-Authors: Peter G. N. Neate, Mark D. Greenhalgh, William W. Brennessel, Stephen P. Thomas, Michael L. NeidigAbstract:N,N,N',N'-Tetramethylethylenediamine (TMEDA) has been one of the most prevalent and successful additives used in iron catalysis, finding application in reactions as diverse as cross-coupling, C-H activation, and borylation. However, the role that TMEDA plays in these reactions remains largely undefined. Herein, studying the iron-catalyzed Hydromagnesiation of styrene derivatives using TMEDA has provided molecular-level insight into the role of TMEDA in achieving effective catalysis. The key is the initial formation of TMEDA-iron(II)-alkyl species which undergo a controlled reduction to selectively form catalytically active styrene-stabilized iron(0)-alkyl complexes. While TMEDA is not bound to the catalytically active species, these active iron(0) complexes cannot be accessed in the absence of TMEDA. This mode of action, allowing for controlled reduction and access to iron(0) species, represents a new paradigm for the role of this important reaction additive in iron catalysis.
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Mechanism of the Bis(imino)pyridine-Iron-Catalyzed Hydromagnesiation of Styrene Derivatives.
Journal of the American Chemical Society, 2019Co-Authors: Peter G. N. Neate, Mark D. Greenhalgh, William W. Brennessel, Stephen P. Thomas, Michael L. NeidigAbstract:Iron-catalyzed Hydromagnesiation of styrene derivatives offers a rapid and efficient method to generate benzylic Grignard reagents, which can be applied in a range of transformations to provide products of formal hydrofunctionalization. While iron-catalyzed methodologies exist for the Hydromagnesiation of terminal alkenes, internal alkynes, and styrene derivatives, the underlying mechanisms of catalysis remain largely undefined. To address this issue and determine the divergent reactivity from established cross-coupling and hydrofunctionalization reactions, a detailed study of the bis(imino)pyridine iron-catalyzed Hydromagnesiation of styrene derivatives is reported. Using a combination of kinetic analysis, deuterium labeling, and reactivity studies as well as in situ 57Fe Mossbauer spectroscopy, key mechanistic features and species were established. A formally iron(0) ate complex [ iPrBIPFe(Et)(CH2═CH2)]- was identified as the principle resting state of the catalyst. Dissociation of ethene forms the catalytically active species which can reversibly coordinate the styrene derivative and mediate a direct and reversible β-hydride transfer, negating the necessity of a discrete iron hydride intermediate. Finally, displacement of the tridentate bis(imino)pyridine ligand over the course of the reaction results in the formation of a tris-styrene-coordinated iron(0) complex, which is also a competent catalyst for Hydromagnesiation.
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Iron-Catalysed Hydrofunctionalisation of Alkenes and Alkynes
2016Co-Authors: Mark D. GreenhalghAbstract:The metal-catalysed hydrofunctionalisation of alkenes and alkynes provides a convenient and atom-economic route to diversely functionalised products with control of regio-, chemo- and stereoselectivity. As one of the most abundant elements on earth, iron offers a level of sustainable and long-term availability that is uncommon for most transition metals. Although iron is commonly found in the oxidation states of +2 and +3, the use of redox-active ligands has allowed the synthesis and application of low oxidation state iron complexes in catalysis. A broad range of hydrofunctionalisation reactions have been developed by using iron catalysts in a wide variety of oxidation states. Intense development over the past decade has resulted in the development of iron-catalysed hydroamination, hydroalkoxylation, hydrocarboxylation, hydrothiolation, hydrovinylation, hydrosilylation, hydroboration, hydrophosphination, Hydromagnesiation and carbonylation reactions, amongst others. With the field still in its infancy, there is great potential for further developments in the mechanistic understanding and synthetic and industrial applicability of these processes.
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Iron-Catalysed Hydromagnesiation of Styrene Derivatives
Iron-Catalysed Hydrofunctionalisation of Alkenes and Alkynes, 2016Co-Authors: Mark D. GreenhalghAbstract:Grignard reagents are highly versatile organometallic reagents, and can be used for the formation of a range of carbon-carbon and carbon-heteroatom bonds, through reaction with electrophiles, or by cross-coupling methodologies. The Hydromagnesiation of alkenes, dienes and alkynes provides an alternative method for the synthesis of alkyl-, allyl and vinyl Grignard reagents which may be challenging to prepare by conventional methods. This chapter deals with the development of an iron-catalysed methodology for the Hydromagnesiation of styrene derivatives to give benzylic Grignard reagents. The reaction scope and limitations are presented along with a discussion of possible reaction mechanisms based on in-depth mechanistic studies.
Michael L. Neidig - One of the best experts on this subject based on the ideXlab platform.
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tmeda in iron catalyzed Hydromagnesiation formation of iron ii alkyl species for controlled reduction to alkene stabilized iron 0
Angewandte Chemie, 2020Co-Authors: Peter G. N. Neate, Mark D. Greenhalgh, William W. Brennessel, Stephen P. Thomas, Michael L. NeidigAbstract:N,N,N',N'-Tetramethylethylenediamine (TMEDA) has been one of the most prevalent and successful additives used in iron catalysis, finding application in reactions as diverse as cross-coupling, C-H activation, and borylation. However, the role that TMEDA plays in these reactions remains largely undefined. Herein, studying the iron-catalyzed Hydromagnesiation of styrene derivatives using TMEDA has provided molecular-level insight into the role of TMEDA in achieving effective catalysis. The key is the initial formation of TMEDA-iron(II)-alkyl species which undergo a controlled reduction to selectively form catalytically active styrene-stabilized iron(0)-alkyl complexes. While TMEDA is not bound to the catalytically active species, these active iron(0) complexes cannot be accessed in the absence of TMEDA. This mode of action, allowing for controlled reduction and access to iron(0) species, represents a new paradigm for the role of this important reaction additive in iron catalysis.
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TMEDA in Iron‐Catalyzed Hydromagnesiation: Formation of Iron(II)‐Alkyl Species for Controlled Reduction to Alkene‐Stabilized Iron(0)
Angewandte Chemie (International ed. in English), 2020Co-Authors: Peter G. N. Neate, Mark D. Greenhalgh, William W. Brennessel, Stephen P. Thomas, Michael L. NeidigAbstract:N,N,N',N'-Tetramethylethylenediamine (TMEDA) has been one of the most prevalent and successful additives used in iron catalysis, finding application in reactions as diverse as cross-coupling, C-H activation, and borylation. However, the role that TMEDA plays in these reactions remains largely undefined. Herein, studying the iron-catalyzed Hydromagnesiation of styrene derivatives using TMEDA has provided molecular-level insight into the role of TMEDA in achieving effective catalysis. The key is the initial formation of TMEDA-iron(II)-alkyl species which undergo a controlled reduction to selectively form catalytically active styrene-stabilized iron(0)-alkyl complexes. While TMEDA is not bound to the catalytically active species, these active iron(0) complexes cannot be accessed in the absence of TMEDA. This mode of action, allowing for controlled reduction and access to iron(0) species, represents a new paradigm for the role of this important reaction additive in iron catalysis.
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Mechanism of the Bis(imino)pyridine-Iron-Catalyzed Hydromagnesiation of Styrene Derivatives.
Journal of the American Chemical Society, 2019Co-Authors: Peter G. N. Neate, Mark D. Greenhalgh, William W. Brennessel, Stephen P. Thomas, Michael L. NeidigAbstract:Iron-catalyzed Hydromagnesiation of styrene derivatives offers a rapid and efficient method to generate benzylic Grignard reagents, which can be applied in a range of transformations to provide products of formal hydrofunctionalization. While iron-catalyzed methodologies exist for the Hydromagnesiation of terminal alkenes, internal alkynes, and styrene derivatives, the underlying mechanisms of catalysis remain largely undefined. To address this issue and determine the divergent reactivity from established cross-coupling and hydrofunctionalization reactions, a detailed study of the bis(imino)pyridine iron-catalyzed Hydromagnesiation of styrene derivatives is reported. Using a combination of kinetic analysis, deuterium labeling, and reactivity studies as well as in situ 57Fe Mossbauer spectroscopy, key mechanistic features and species were established. A formally iron(0) ate complex [ iPrBIPFe(Et)(CH2═CH2)]- was identified as the principle resting state of the catalyst. Dissociation of ethene forms the catalytically active species which can reversibly coordinate the styrene derivative and mediate a direct and reversible β-hydride transfer, negating the necessity of a discrete iron hydride intermediate. Finally, displacement of the tridentate bis(imino)pyridine ligand over the course of the reaction results in the formation of a tris-styrene-coordinated iron(0) complex, which is also a competent catalyst for Hydromagnesiation.
Shunsuke Chiba - One of the best experts on this subject based on the ideXlab platform.
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Hydromagnesiation of 1 3 enynes by magnesium hydride for synthesis of tri and tetra substituted allenes
Angewandte Chemie, 2021Co-Authors: Bin Wang, Jia Hao Pang, Kohei Watanabe, Ryo Takita, Shunsuke ChibaAbstract:A protocol for regio-controlled Hydromagnesiation of 1,3-enynes was developed using magnesium hydride that is generated in situ by solvothermal treatment of sodium hydride (NaH) and magnesium iodide (MgI2 ) in THF. The resulting allenylmagnesium species could be converted into tri- and tetra-substituted allenes by subsequent treatment with various carbon- and silicon-based electrophiles with the aid of CuCN as a catalyst.
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Hydromagnesiation of 1,3‐enynes by magnesium hydride for synthesis of tri‐ and tetra‐substituted allenes
Angewandte Chemie (International ed. in English), 2020Co-Authors: Bin Wang, Jia Hao Pang, Kohei Watanabe, Ryo Takita, Shunsuke ChibaAbstract:A protocol for regio-controlled Hydromagnesiation of 1,3-enynes was developed using magnesium hydride that is generated in situ by solvothermal treatment of sodium hydride (NaH) and magnesium iodide (MgI2 ) in THF. The resulting allenylmagnesium species could be converted into tri- and tetra-substituted allenes by subsequent treatment with various carbon- and silicon-based electrophiles with the aid of CuCN as a catalyst.
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Stereo-controlled anti-Hydromagnesiation of aryl alkynes by magnesium hydrides
Chemical Science, 2020Co-Authors: Bin Wang, Jia Hao Pang, Kohei Watanabe, Ryo Takita, Derek Yiren Ong, Shunsuke ChibaAbstract:A concise protocol for anti-Hydromagnesiation of aryl alkynes was established using 1 : 1 molar combination of sodium hydride (NaH) and magnesium iodide (MgI2) without the aid of any transition metal catalysts. The resulting alkenylmagnesium intermediates could be trapped with a series of electrophiles, thus providing facile accesses to stereochemically well-defined functionalized alkenes. Mechanistic studies by experimental and theoretical approaches imply that polar hydride addition from magnesium hydride (MgH2) is responsible for the process.
