The Experts below are selected from a list of 5502 Experts worldwide ranked by ideXlab platform
Peter R Schreiner - One of the best experts on this subject based on the ideXlab platform.
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evolution of asymmetric Organocatalysis multi and retrocatalysis
Green Chemistry, 2012Co-Authors: Raffael C Wende, Peter R SchreinerAbstract:The evolution of Organocatalysis led to various valuable approaches, such as multicomponent as well as domino and tandem reactions. Recently, organomulticatalysis, i.e., the modular combination of distinct organocatalysts enabling consecutive reactions to be performed in one pot, has become a powerful tool in organic synthesis. It allows the construction of complex molecules from simple and readily available starting materials, thereby maximizing reaction efficiency and sustainability. A logical extension of conventional multicatalysis is a multicatalyst, i.e., a catalyst backbone equipped with independent, orthogonally reactive catalytic moieties. Herein we highlight the impressive advantages of asymmetric organomulticatalysis, examine its development, and present detailed reactions based on the catalyst classes employed, ranging from the very beginnings to the latest multicatalyst systems.
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thio urea Organocatalysis what can be learnt from anion recognition
Chemical Society Reviews, 2009Co-Authors: Zhiguo Zhang, Peter R SchreinerAbstract:The present critical review outlines the close relationship and mutual interplay between molecular recognition, active site considerations in enzyme catalysis involving anions, and Organocatalysis utilizing explicit hydrogen bonding. These interconnections are generally not made although, as we demonstrate, they are quite apparent as exemplified with pertinent examples in the field of (thio)urea Organocatalysis. Indeed, the concepts of anion binding or binding with negatively (partially) charged heteroatoms is key for designing new organocatalytic transformations. Utilizing anions through recognition with hydrogen-bonding organocatalysts is still in its infancy but bears great potential. In turn, the discovery and mechanistic elucidation of such reactions is likely to improve the understanding of enzyme active sites (108 references).
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(Thio)urea Organocatalysis—What can be learnt from anion recognition?
Chemical Society Reviews, 2009Co-Authors: Zhiguo Zhang, Peter R SchreinerAbstract:The present critical review outlines the close relationship and mutual interplay between molecular recognition, active site considerations in enzyme catalysis involving anions, and Organocatalysis utilizing explicit hydrogen bonding. These interconnections are generally not made although, as we demonstrate, they are quite apparent as exemplified with pertinent examples in the field of (thio)urea Organocatalysis. Indeed, the concepts of anion binding or binding with negatively (partially) charged heteroatoms is key for designing new organocatalytic transformations. Utilizing anions through recognition with hydrogen-bonding organocatalysts is still in its infancy but bears great potential. In turn, the discovery and mechanistic elucidation of such reactions is likely to improve the understanding of enzyme active sites (108 references).
Haritz Sardon - One of the best experts on this subject based on the ideXlab platform.
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Organocatalysis for depolymerisation
Polymer Chemistry, 2019Co-Authors: Jeremy Demarteau, Maria M Perezmadrigal, C Jehanno, Haritz Sardon, Andrew P. DoveAbstract:Polymeric materials have been accumulating in the environment for decades as a result of the linear way of consuming plastics. Unfortunately, the current approaches followed to treat such a large amount of plastic waste, mainly involving physical recycling or pyrolysis, are not efficient enough. Recently, chemical degradation has emerged as a long-term strategy towards reaching completely sustainable cycles where plastics are polymerised, depolymerised, and then re-polymerised with minimal changes in their quantity or final properties. Organocatalysts, which are promising “green” substitutes for traditional organometallic complexes, are able to catalyse depolymerisation reactions yielding highly pure small molecules that are adequate for subsequent polymerisations or other uses. Moreover, by varying several reaction parameters (e.g. solvent, temperature, concentration, co-catalyst, etc.), the depolymerisation products can be tuned in innumerable possibilities, which further evidences the versatility of depolymerisation. In this review, we highlight the recent advances made by applying organocatalysts, such as organic bases, organic acids, and ionic compounds, to chemically degrade the most commonly used commercial polymers. Indeed, Organocatalysis is envisaged as a promising tool to reach a circular and environmentally friendly plastic economy.
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Opportunities for Organocatalysis in polymer synthesis via step-growth methods
Progress in Polymer Science, 2019Co-Authors: Amaury Bossion, Daniel Taton, Katherine V. Heifferon, Leire Meabe, Nicolas Zivic, James L. Hedrick, Timothy E. Long, Haritz SardonAbstract:Abstract Organocatalysis has emerged as an invaluable tool for polymer synthesis and has already demonstrated versatility for replacing organometallic catalysts in many polymerization reactions. The overall ease of removal and lower toxicity of organocatalysts relative to their common metal counterparts has also nurtured development especially in chain growth polymerizations to achieve precision macromolecular architectures for application in the biomedical space. The application of organocatalysts in step-growth polymerizations of polymers, including polyesters, polycarbonates, and polyurethanes, has garnered fewer studies in spite of the large array of benefits that could be achieved. Step-growth polymers account for nearly 20 wt. % of the Word Plastic Production and play a vital role in many technologies as engineering plastics and high performance polymeric materials with outstanding thermomechanical performance. Step-growth polymerizations are achieved using monomers with a diversity of chemical functionality. Consequently, a vast array of polymeric structures are attainable and will impact diverse applications in energy, aerospace, medicine, transportation, and construction. This review article will highlight the recent advances in Organocatalysis in step growth polymerizations. We will primarily focus our review on the synthesis of commercially important polyesters and polyurethanes using Organocatalysis, however, the review will also emphasize recent literature describing less explored polymers, such as polyethers, polycarbonates, and polybenzoins, which have recently employed organocatalysts. Moreover, the article will draw attention to recent efforts in the use of carbon dioxide as a monomer for the preparation of step-growth polymers in the presence of Organocatalysis.
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update and challenges in organo mediated polymerization reactions
Progress in Polymer Science, 2016Co-Authors: Winnie Nzahou Ottou, Haritz Sardon, David Mecerreyes, Joan Vignolle, Daniel TatonAbstract:Abstract Organocatalysis has become a very powerful tool for precision macromolecular chemistry, as judged by the number of articles published in this field in the past decade. A variety of small organic molecules, including Bronsted/Lewis bases and acids, based on amines, phosphines or carbenes, but also on bi-component systems, have been employed as a means to catalyze the polymerization of miscellaneous monomers. Not only can organocatalysts be employed to promote the ring-opening polymerization of various heterocyclics (e.g. lactones, lactide, cyclic carbonates, epoxides, lactams, cyclocarbosiloxanes), but some of them also allow activating vinylic monomers such as (meth)acrylics, or triggering the step-growth polymerization of monomers such as diisocyanates and diols for polyurethane synthesis. The reduced toxicity of organocatalysts in comparison to their metallic counterparts is also driving their development in some sensitive applications, such as biomedical or microelectronics. Overall, organocatalysts display specific monomer activation modes, thereby providing a unique opportunity to control the polymerization of various functional monomers, under mild conditions. This review article focuses on advances of the past 4 years (>150 publications) in polymerization reactions utilizing small organic molecules either as direct initiators or as true catalysts, with a special emphasis on monomer activation modes, as well as polymerization mechanism aspects.
Daniel Taton - One of the best experts on this subject based on the ideXlab platform.
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Opportunities for Organocatalysis in polymer synthesis via step-growth methods
Progress in Polymer Science, 2019Co-Authors: Amaury Bossion, Daniel Taton, Katherine V. Heifferon, Leire Meabe, Nicolas Zivic, James L. Hedrick, Timothy E. Long, Haritz SardonAbstract:Abstract Organocatalysis has emerged as an invaluable tool for polymer synthesis and has already demonstrated versatility for replacing organometallic catalysts in many polymerization reactions. The overall ease of removal and lower toxicity of organocatalysts relative to their common metal counterparts has also nurtured development especially in chain growth polymerizations to achieve precision macromolecular architectures for application in the biomedical space. The application of organocatalysts in step-growth polymerizations of polymers, including polyesters, polycarbonates, and polyurethanes, has garnered fewer studies in spite of the large array of benefits that could be achieved. Step-growth polymers account for nearly 20 wt. % of the Word Plastic Production and play a vital role in many technologies as engineering plastics and high performance polymeric materials with outstanding thermomechanical performance. Step-growth polymerizations are achieved using monomers with a diversity of chemical functionality. Consequently, a vast array of polymeric structures are attainable and will impact diverse applications in energy, aerospace, medicine, transportation, and construction. This review article will highlight the recent advances in Organocatalysis in step growth polymerizations. We will primarily focus our review on the synthesis of commercially important polyesters and polyurethanes using Organocatalysis, however, the review will also emphasize recent literature describing less explored polymers, such as polyethers, polycarbonates, and polybenzoins, which have recently employed organocatalysts. Moreover, the article will draw attention to recent efforts in the use of carbon dioxide as a monomer for the preparation of step-growth polymers in the presence of Organocatalysis.
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update and challenges in organo mediated polymerization reactions
Progress in Polymer Science, 2016Co-Authors: Winnie Nzahou Ottou, Haritz Sardon, David Mecerreyes, Joan Vignolle, Daniel TatonAbstract:Abstract Organocatalysis has become a very powerful tool for precision macromolecular chemistry, as judged by the number of articles published in this field in the past decade. A variety of small organic molecules, including Bronsted/Lewis bases and acids, based on amines, phosphines or carbenes, but also on bi-component systems, have been employed as a means to catalyze the polymerization of miscellaneous monomers. Not only can organocatalysts be employed to promote the ring-opening polymerization of various heterocyclics (e.g. lactones, lactide, cyclic carbonates, epoxides, lactams, cyclocarbosiloxanes), but some of them also allow activating vinylic monomers such as (meth)acrylics, or triggering the step-growth polymerization of monomers such as diisocyanates and diols for polyurethane synthesis. The reduced toxicity of organocatalysts in comparison to their metallic counterparts is also driving their development in some sensitive applications, such as biomedical or microelectronics. Overall, organocatalysts display specific monomer activation modes, thereby providing a unique opportunity to control the polymerization of various functional monomers, under mild conditions. This review article focuses on advances of the past 4 years (>150 publications) in polymerization reactions utilizing small organic molecules either as direct initiators or as true catalysts, with a special emphasis on monomer activation modes, as well as polymerization mechanism aspects.
Zhiguo Zhang - One of the best experts on this subject based on the ideXlab platform.
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thio urea Organocatalysis what can be learnt from anion recognition
Chemical Society Reviews, 2009Co-Authors: Zhiguo Zhang, Peter R SchreinerAbstract:The present critical review outlines the close relationship and mutual interplay between molecular recognition, active site considerations in enzyme catalysis involving anions, and Organocatalysis utilizing explicit hydrogen bonding. These interconnections are generally not made although, as we demonstrate, they are quite apparent as exemplified with pertinent examples in the field of (thio)urea Organocatalysis. Indeed, the concepts of anion binding or binding with negatively (partially) charged heteroatoms is key for designing new organocatalytic transformations. Utilizing anions through recognition with hydrogen-bonding organocatalysts is still in its infancy but bears great potential. In turn, the discovery and mechanistic elucidation of such reactions is likely to improve the understanding of enzyme active sites (108 references).
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(Thio)urea Organocatalysis—What can be learnt from anion recognition?
Chemical Society Reviews, 2009Co-Authors: Zhiguo Zhang, Peter R SchreinerAbstract:The present critical review outlines the close relationship and mutual interplay between molecular recognition, active site considerations in enzyme catalysis involving anions, and Organocatalysis utilizing explicit hydrogen bonding. These interconnections are generally not made although, as we demonstrate, they are quite apparent as exemplified with pertinent examples in the field of (thio)urea Organocatalysis. Indeed, the concepts of anion binding or binding with negatively (partially) charged heteroatoms is key for designing new organocatalytic transformations. Utilizing anions through recognition with hydrogen-bonding organocatalysts is still in its infancy but bears great potential. In turn, the discovery and mechanistic elucidation of such reactions is likely to improve the understanding of enzyme active sites (108 references).
Xumu Zhang - One of the best experts on this subject based on the ideXlab platform.
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metalOrganocatalysis cooperating transition metal catalysis and Organocatalysis through a covalent bond
Organic chemistry frontiers, 2015Co-Authors: Xiuqin Dong, Qingyang Zhao, Caiyou Chen, Xumu ZhangAbstract:Asymmetric catalysis has grown rapidly and made considerable progress in the last few decades, but there still remain significantly unachievable reactions through either Organocatalysis or transition-metal catalysis alone. The concept of combination of transition-metal catalysis with Organocatalysis emerged as a powerful strategy for developing asymmetric catalysis, and has attracted great attention. In order to avoid the incompatibility existing in catalysts, substrates, intermediates and solvents through combining transition-metal catalysis and Organocatalysis, it is urgently necessary to develop a new catalytic strategy to resolve these problems. Therefore, we are devoted to designing a series of novel bifunctional catalysts based upon the synergistic activation strategy via cooperating transition metal-catalysis and Organocatalysis through a covalent bond forming a bifunctional molecule. In this review, this momentous strategy is illustrated with several recent outstanding examples and prospective promising applications, with the aim of elaborating the synthetic utilities and potentialities of this concept as a powerful tool in organic synthesis.
