0000000000266313
AUTHOR
Bernd Elsler
ChemInform Abstract: Efficient Anodic and Direct Phenol-Arene C,C Cross-Coupling: The Benign Role of Water or Methanol.
For the first time a significantly improved electrochemical C-C cross-coupling is reported.
Metal- and reagent-free highly selective anodic cross-coupling reaction of phenols.
The direct oxidative cross-coupling of phenols is a very challenging transformation, as homo-coupling is usually strongly preferred. Electrochemical methods circumvent the use of oxidizing reagents or metal catalysts and are therefore highly attractive. Employing electrolytes with a high capacity for hydrogen bonding, such as methanol with formic acid or 1,1,1,3,3,3-hexafluoro-2-propanol, a direct electrolysis in an undivided cell provides mixed 2,2′-biphenols with high selectivity. This mild method tolerates a variety of moieties, for example, tert-butyl groups, which are not compatible with other strong electrophilic media but vital for later catalytic applications of the formed products.
Innentitelbild: Reagens- und metallfreie anodische C-C-Kreuzkupplung von Anilinderivaten (Angew. Chem. 17/2017)
Cover Picture: Source of Selectivity in Oxidative Cross-Coupling of Aryls by Solvent Effect of 1,1,1,3,3,3-Hexafluoropropan-2-ol (Chem. Eur. J. 35/2015)
ChemInform Abstract: Synthesis of meta-Terphenyl-2,2′′-diols by Anodic C-C Cross-Coupling Reactions.
The anodic C−C cross-coupling reaction is a versatile synthetic approach to symmetric and non-symmetric biphenols and arylated phenols. We herein present a metal-free electrosynthetic method that provides access to symmetric and non-symmetric meta-terphenyl-2,2′′-diols in good yields and high selectivity. Symmetric derivatives can be obtained by direct electrolysis in an undivided cell. The synthesis of non-symmetric meta-terphenyl-2,2′′-diols required two electrochemical steps. The reactions are easy to conduct and scalable. The method also features a broad substrate scope, and a large variety of functional groups are tolerated. The target molecules may serve as [OCO]3− pincer ligands.
Source of Selectivity in Oxidative Cross-Coupling of Aryls by Solvent Effect of 1,1,1,3,3,3-Hexafluoropropan-2-ol
Abstract Solvents such as 1,1,1,3,3,3-hexafluoroisopropanol (HFIP) with a high capacity for donating hydrogen bonds generate solvates that enter into selective cross-coupling reactions of aryls upon oxidation. When electric current is employed for oxidation, reagent effects can be excluded and a decoupling of nucleophilicity from oxidation potential can be achieved. The addition of water or methanol to the electrolyte allows a shift of oxidation potentials in a specific range, creating suitable systems for selective anodic cross-coupling reactions. The shift in the redox potentials depends on the substitution pattern of the substrate employed. The concept has been expanded from arene-phenol…
ChemInform Abstract: Source of Selectivity in Oxidative Cross-Coupling of Aryls by Solvent Effect of 1,1,1,3,3,3-Hexafluoropropan-2-ol.
Abstract Solvents such as 1,1,1,3,3,3-hexafluoroisopropanol (HFIP) with a high capacity for donating hydrogen bonds generate solvates that enter into selective cross-coupling reactions of aryls upon oxidation. When electric current is employed for oxidation, reagent effects can be excluded and a decoupling of nucleophilicity from oxidation potential can be achieved. The addition of water or methanol to the electrolyte allows a shift of oxidation potentials in a specific range, creating suitable systems for selective anodic cross-coupling reactions. The shift in the redox potentials depends on the substitution pattern of the substrate employed. The concept has been expanded from arene-phenol…
Synthesis ofmeta-Terphenyl-2,2′′-diols by Anodic C−C Cross-Coupling Reactions
The anodic C-C cross-coupling reaction is a versatile synthetic approach to symmetric and non-symmetric biphenols and arylated phenols. We herein present a metal-free electrosynthetic method that provides access to symmetric and non-symmetric meta-terphenyl-2,2''-diols in good yields and high selectivity. Symmetric derivatives can be obtained by direct electrolysis in an undivided cell. The synthesis of non-symmetric meta-terphenyl-2,2''-diols required two electrochemical steps. The reactions are easy to conduct and scalable. The method also features a broad substrate scope, and a large variety of functional groups are tolerated. The target molecules may serve as [OCO](3-) pincer ligands.
Inside Cover: Reagent- and Metal-Free Anodic C−C Cross-Coupling of Aniline Derivatives (Angew. Chem. Int. Ed. 17/2017)
Synthesis of iodobiaryls and dibenzofurans by direct coupling at BDD anodes.
The first direct oxidative phenol-arene cross-coupling reactions of an iodine-containing guaiacol derivative and the possible over-oxidation products of electron-rich phenols are described. Hereby, a "green" and targeted synthesis for dibenzofurans was developed.
Efficient Anodic and Direct Phenol-Arene C,C Cross-Coupling: The Benign Role of Water or Methanol
C,C cross-coupling reactions for the synthesis of nonsymmetrical biaryls represent one of the most significant transformations in contemporary organic chemistry. A variety of useful synthetic methods have been developed in recent decades, since nonsymmetrical biaryls play an evident role in natural product synthesis, as ligand systems in homogeneous catalysis and materials science. Transformation of simple arenes by direct C,H activation belongs to the cutting-edge strategies for creating biaryls; in particular the 2-fold C,H activation is of significant interest. However, in most examples very costly noble metal catalysts, ligand systems, and significant amount of waste-producing oxidants …
Synthese vonmeta-Terphenyl-2,2′′-diolen durch anodische C-C-Kreuzkupplungen
Die anodische C-C-Kreuzkupplung ist eine vielseitig einsetzbare Transformation, die eine gezielte Synthese von Biphenolen und arylierten Phenolen ermoglicht. Wir berichten uber einen ebenfalls elektrosynthetischen, metallfreien Ansatz, der einen Zugang zu symmetrischen und nichtsymmetrischen meta-Terphenyl-2,2′′-diolen in guten Ausbeuten und hoher Selektivitat ermoglicht. Symmetrische Derivate konnen durch eine direkte Synthese in einer ungeteilten Zelle gewonnen werden, wohingegen nichtsymmetrische meta-Terphenyl-2,2′′-diole zwei elektrochemische Stufen benotigen. Die milde Methode ist einfach durchzufuhren und skalierbar. Auserdem konnte erstmalig eine breite Substratvariabilitat aufgezei…
Metall- und reagensfreie hochselektive anodische Kreuzkupplung von Phenolen
Reaction Condition Screening by Using Electrochemical Microreactor: Application to Anodic Phenol-arene C,C Cross-Coupling Reaction in High Acceptor Number Media
The anodic phenol-arene C,C cross-coupling reaction was achieved in inexpensive and sustainable media such as methanol, acetic acid, and formic acid by using an electrochemical microreactor which can provide a better performance to screen reaction conditions than in standard beaker-type electrolysis cells. Especially, formic acid as a reaction medium showed good performance. The total amount of cross-coupling product and homo-coupling products as a by-product was clearly increased as the solvent acceptor number increased. To control the selective oxidation of phenol, addition of methanol was effective.
Cover Picture: Metal‐ and Reagent‐Free Highly Selective Anodic Cross‐Coupling Reaction of Phenols (Angew. Chem. Int. Ed. 20/2014)
ChemInform Abstract: Metal- and Reagent-Free Highly Selective Anodic Cross-Coupling Reaction of Phenols.
Boron-doped diamond electrodes allow the direct anodic cross-coupling of phenols in hexafluoroisopropanol without using leaving functions or protecting groups.
Reagens- und metallfreie anodische C-C-Kreuzkupplung von Anilinderivaten
Vorgestellt wird die oxidative Kreuzkupplung von Anilinderivaten zu 2,2′-Diaminobiarylen. Der Oxidationsschritt wird elektrochemisch durchgefuhrt, ohne die Notwendigkeit von Metallen und Reagenzien. Ein breites Spektrum an Biphenyldiaminen konnte hergestellt werden. Die besten Resultate wurden mit Glaskohlenstoff als Anodenmaterial erhalten. Die elektrochemische Umsetzung kann problemlos in einer ungeteilten Zelle bei leicht erhohten Temperaturen durchgefuhrt werden. Auserdem wurden gebrauchliche, auf Carbonsauren basierende, Schutzgruppen verwendet, die nach der Kreuzkupplung unter milden Bedingungen selektiv abgespalten werden konnen. Auf diese Weise erhalt man schnell und effizient Zugan…
Electrochemical synthesis on boron-doped diamond
Abstract Boron-doped diamond (BDD) is a novel and innovative electrode material. In protic media and particular aqueous electrolytes BDD exhibits a large over potential for the evolution of molecular hydrogen and oxygen. The large chemical window allows a variety of electrochemical conversions to be conducted. The anodic process treatment generates oxyl species directly which are known to be extremely reactive. Usually, the electrochemical mineralization of the organic components in the electrolyte occurs. However, with control of the reactivity of these intermediates the use in electroorganic synthesis can be realized. Until today mostly anodic conversions have been studied at BDD. Since h…
Titelbild: Metall- und reagensfreie hochselektive anodische Kreuzkupplung von Phenolen (Angew. Chem. 20/2014)
Reagent- and Metal-Free Anodic C-C Cross-Coupling of Aniline Derivatives.
The dehydrogenative cross-coupling of aniline derivatives to 2,2′-diaminobiaryls is reported. The oxidation is carried out electrochemically, which avoids the use of metals and reagents. A large variety of biphenyldiamines were thus prepared. The best results were obtained when glassy carbon was used as the anode material. The electrosynthetic reaction is easily performed in an undivided cell at slightly elevated temperature. In addition, common amine protecting groups based on carboxylic acids were employed that can be selectively removed under mild conditions after the cross-coupling, which provides quick and efficient access to important building blocks featuring free amine moieties.
CCDC 1485994: Experimental Crystal Structure Determination
Related Article: Sebastian Lips, Anton Wiebe, Bernd Elsler, Dieter Schollmeyer, Katrin M. Dyballa, Robert Franke, Siegfried R. Waldvogel|2016|Angew.Chem.,Int.Ed.|55|10872|doi:10.1002/anie.201605865
CCDC 980571: Experimental Crystal Structure Determination
Related Article: Bernd Elsler, Dieter Schollmeyer, Katrin Marie Dyballa, Robert Franke and Siegfried R. Waldvogel|2014|Angew.Chem.,Int.Ed.|53|5210|doi:10.1002/anie.201400627
CCDC 1517624: Experimental Crystal Structure Determination
Related Article: Lara Schulz, Mathias Enders, Bernd Elsler, Dieter Schollmeyer, Katrin M. Dyballa, Robert Franke, Siegfried R. Waldvogel|2017|Angew.Chem.,Int.Ed.|56|4877|doi:10.1002/anie.201612613
CCDC 980570: Experimental Crystal Structure Determination
Related Article: Bernd Elsler, Dieter Schollmeyer, Katrin Marie Dyballa, Robert Franke and Siegfried R. Waldvogel|2014|Angew.Chem.,Int.Ed.|53|5210|doi:10.1002/anie.201400627
CCDC 980563: Experimental Crystal Structure Determination
Related Article: Bernd Elsler, Dieter Schollmeyer, Katrin Marie Dyballa, Robert Franke and Siegfried R. Waldvogel|2014|Angew.Chem.,Int.Ed.|53|5210|doi:10.1002/anie.201400627
CCDC 980565: Experimental Crystal Structure Determination
Related Article: Bernd Elsler, Dieter Schollmeyer, Katrin Marie Dyballa, Robert Franke and Siegfried R. Waldvogel|2014|Angew.Chem.,Int.Ed.|53|5210|doi:10.1002/anie.201400627
CCDC 1485996: Experimental Crystal Structure Determination
Related Article: Sebastian Lips, Anton Wiebe, Bernd Elsler, Dieter Schollmeyer, Katrin M. Dyballa, Robert Franke, Siegfried R. Waldvogel|2016|Angew.Chem.,Int.Ed.|55|10872|doi:10.1002/anie.201605865
CCDC 980569: Experimental Crystal Structure Determination
Related Article: Bernd Elsler, Dieter Schollmeyer, Katrin Marie Dyballa, Robert Franke and Siegfried R. Waldvogel|2014|Angew.Chem.,Int.Ed.|53|5210|doi:10.1002/anie.201400627
CCDC 1517625: Experimental Crystal Structure Determination
Related Article: Lara Schulz, Mathias Enders, Bernd Elsler, Dieter Schollmeyer, Katrin M. Dyballa, Robert Franke, Siegfried R. Waldvogel|2017|Angew.Chem.,Int.Ed.|56|4877|doi:10.1002/anie.201612613
CCDC 980564: Experimental Crystal Structure Determination
Related Article: Bernd Elsler, Dieter Schollmeyer, Katrin Marie Dyballa, Robert Franke and Siegfried R. Waldvogel|2014|Angew.Chem.,Int.Ed.|53|5210|doi:10.1002/anie.201400627
CCDC 980568: Experimental Crystal Structure Determination
Related Article: Bernd Elsler, Dieter Schollmeyer, Katrin Marie Dyballa, Robert Franke and Siegfried R. Waldvogel|2014|Angew.Chem.,Int.Ed.|53|5210|doi:10.1002/anie.201400627
CCDC 1008816: Experimental Crystal Structure Determination
Related Article: Bernd Elsler, Anton Wiebe, Dieter Schollmeyer, Katrin M. Dyballa, Robert Franke, Siegfried R. Waldvogel|2015|Chem.-Eur.J.|21|12321|doi:10.1002/chem.201501604
CCDC 1008819: Experimental Crystal Structure Determination
Related Article: Bernd Elsler, Anton Wiebe, Dieter Schollmeyer, Katrin M. Dyballa, Robert Franke, Siegfried R. Waldvogel|2015|Chem.-Eur.J.|21|12321|doi:10.1002/chem.201501604
CCDC 1485995: Experimental Crystal Structure Determination
Related Article: Sebastian Lips, Anton Wiebe, Bernd Elsler, Dieter Schollmeyer, Katrin M. Dyballa, Robert Franke, Siegfried R. Waldvogel|2016|Angew.Chem.,Int.Ed.|55|10872|doi:10.1002/anie.201605865
CCDC 1008820: Experimental Crystal Structure Determination
Related Article: Bernd Elsler, Anton Wiebe, Dieter Schollmeyer, Katrin M. Dyballa, Robert Franke, Siegfried R. Waldvogel|2015|Chem.-Eur.J.|21|12321|doi:10.1002/chem.201501604
CCDC 980566: Experimental Crystal Structure Determination
Related Article: Bernd Elsler, Dieter Schollmeyer, Katrin Marie Dyballa, Robert Franke and Siegfried R. Waldvogel|2014|Angew.Chem.,Int.Ed.|53|5210|doi:10.1002/anie.201400627
CCDC 1008818: Experimental Crystal Structure Determination
Related Article: Bernd Elsler, Anton Wiebe, Dieter Schollmeyer, Katrin M. Dyballa, Robert Franke, Siegfried R. Waldvogel|2015|Chem.-Eur.J.|21|12321|doi:10.1002/chem.201501604
CCDC 1008817: Experimental Crystal Structure Determination
Related Article: Bernd Elsler, Anton Wiebe, Dieter Schollmeyer, Katrin M. Dyballa, Robert Franke, Siegfried R. Waldvogel|2015|Chem.-Eur.J.|21|12321|doi:10.1002/chem.201501604
CCDC 1485997: Experimental Crystal Structure Determination
Related Article: Sebastian Lips, Anton Wiebe, Bernd Elsler, Dieter Schollmeyer, Katrin M. Dyballa, Robert Franke, Siegfried R. Waldvogel|2016|Angew.Chem.,Int.Ed.|55|10872|doi:10.1002/anie.201605865
CCDC 980567: Experimental Crystal Structure Determination
Related Article: Bernd Elsler, Dieter Schollmeyer, Katrin Marie Dyballa, Robert Franke and Siegfried R. Waldvogel|2014|Angew.Chem.,Int.Ed.|53|5210|doi:10.1002/anie.201400627