Convenient Synthesis of 3-Cinnamoyl-2-styrylchromones: Reinvestigation of the Baker-Venkataraman Rearrangement

An efficient and straightforward, one-pot sequence gives access to highly functionalized 3-cinnamoyl-2-styrylchromones in excellent yields. The low solubility of the target molecules allows convenient isolation. The formation of an α,α-dicinnamoylated acetophenone, as a consequence of a two-fold Baker-Venkataraman sequence, has to be anticipated.

Diversitäts-orientierte Synthese von polycyclischen Gerüsten durch Umsetzung eines von 2,4-Dimethylphenol abgeleiteten anodischen Zwischenproduktes

Cover Picture: Diversity-Oriented Synthesis of Polycyclic Scaffolds by Modification of an Anodic Product Derived from 2,4-Dimethylphenol (Angew. Chem. Int. Ed. 6/2011)

Titelbild: Diversitäts-orientierte Synthese von polycyclischen Gerüsten durch Umsetzung eines von 2,4-Dimethylphenol abgeleiteten anodischen Zwischenproduktes (Angew. Chem. 6/2011)

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.

Electron-Deficient Pyridylimines: Versatile Building Blocks for Functional Metallosupramolecular Chemistry

Metallosupramolecular systems heavily rely on the correct choice of ligands to obtain materials with desired properties. Engaging this problem, we present three ligand systems and six of their mono- and dinuclear complexes, based on the subcomponent self-assembly approach using electron-deficient pyridylcarbaldehyde building blocks. The properties are examined in solution by NMR and UV-vis spectroscopy and CV measurements as well as in solid state by single crystal X-ray diffraction analysis. Ultimately, the choice of ligands allows for fine-tuning of the electronic properties of the metal centers, complex-to-complex transformations, as well as establishing distinct anion-π-interaction moti…

Oxidative Coupling Reactions of 1,3-Diarylpropene Derivatives to Dibenzo[a,c]cycloheptenes by PIFA

The oxidative cyclization reactions of a variety of α-benzyl-cinnamates can be selectively performed with hypervalent iodine as an oxidant. The dibenzo[a,c]cycloheptenes were isolated in up to 55 % yield. When an oxo substrate is applied, the yield was significantly increased. With this synthetic approach, a central intermediate for the synthesis of metasequirin-B was obtained in three steps from very simple starting materials. For this transformation, both aryl moieties have to be activated.

Self-Sorting Effects in the Self-Assembly of Metallosupramolecular Rhombi from Chiral BINOL-Derived Bis(pyridine) Ligands

Four BINOL-based bis(4-pyridyl) ligands were synthesised in enantiopure and racemic form. These ligands form metallosupramolecular [(dppp)2M2L2] rhombi with cis-protected [(dppp)Pd]2+ and [(dppp)Pt]2+ ions. In principle, racemic ligands can self-assemble into three stereoisomeric rhombi. The degree of self-sorting in the self-assembly process crucially depends on the substitution pattern and the resulting bend angle of the V-shaped ligands as well as the degree of steric crowding within the assembly when racemic ligands are used. Thus, these processes either lead to homochiral assemblies in a narcissistic self-recognition manner, to heterochiral assemblies in a social self-discriminating ma…

Novel Domino Oxidative Coupling: C−C Bond Formation Sequence to Highly Functionalized Dibenzo[a,c]cycloheptenes

A domino sequence involving various MoCl(5)-mediated oxidations followed by trapping and supposed [3,3]-sigmatropic rearrangement provides a fast access to the full carbon skeleton of metasequirin-B. A variety of different moieties R(1) and R(2) are tolerated.

Chiral Self‐Sorting of trans ‐Chelating Chiral Ligands upon Formation of Pd II Complexes (Eur. J. Inorg. Chem. 15/2014)

Bis(2,2'-biphenoxy)borates for electrochemical double-layer capacitor electrolytes.

Fluorine makes the difference! Bis(2,2'-biphenoxy)borates decorated with fluorine substituents have been synthesized and studied in supercapacitor test cells (see scheme). A clear trend towards higher electrochemical stability with the increase of the fluorine content has been observed. For a maximum performance, only two fluorine substituents per benzene moiety are required.

Oxidative cyclization reaction of 2-aryl-substituted cinnamates to form phenanthrene carboxylates by using MoCl5.

The oxidative cyclization reaction of 2-aryl cinnamates and derivatives thereof can be easily performed with MoCl5 as the oxidant. This powerful reagent allows oxidative coupling reactions for which other reagents fail. The best results are obtained when the 2-phenyl substituent of the cinnamate is equipped with two methoxy groups. Even iodo moieties in the bay region of phenanthrene are tolerated under the reaction conditions. If naphthalene moieties are involved, a rearrangement of the skeleton occurs, providing an elegant route to highly functionalized angular arenes. The cyclization is demonstrated for 15 example substrates with isolated yields of up to 99 % for the phenanthrene derivat…

Synthesis of all-syn Functionalized Triphenylene Ketals

The stereoselective synthesis of triphenylene ketals offers access to unique scaffolds. For a good performance in supramolecular applications an all-syn orientation of the functional groups is essential. The oxidative trimerization of catechol ketals by molybdenum pentachloride or mixtures with titanium tetrachloride leads to a template-directed formation. Several heterocyclic moieties are suitable for this transformation. A template-directed isomerization of anti,anti,syn isomers to the desired C 3 -symmetric derivative was demonstrated in two cases.

Anodic coupling of guaiacol derivatives on boron-doped diamond electrodes.

The anodic treatment of guaiacol derivatives on boron-doped diamond electrodes (BDD) provides a direct access to nonsymmetrical biphenols, which would require a multistep sequence by conventional methods. Despite the destructive nature of BDD anodes they can be exploited for chemical synthesis.

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 …

ChemInform Abstract: Oxidative Cyclization Reaction of 2-Aryl-Substituted Cinnamates to Form Phenanthrene Carboxylates by Using MoCl5.

The reagent mixture MoCl5/TiCl4 is successfully applied for the oxidative cyclization of α-aryl substituted cinnamates to the corresponding phenanthrenes.

Molybdenum Pentachloride Mediated Synthesis of Spirocyclic Compounds by Intramolecular Oxidative Coupling

The oxidative treatment of (m)ethyl 2-aryl cinnamates equipped with methoxy groups in position 4 of the phenyl moiety promote the formation of cyclohexadienone substructures. This dealkylative oxidative C–C coupling gives access to spirocyclic compounds and avoids the construction of the corresponding phenanthrenes. Furthermore, the transformation can be expanded to other spirocyclic systems.

ChemInform Abstract: Synthesis of Highly Fluorinated 2,2′-Biphenols and 2,2′-Bisanisoles.

The selective Ullmann-type reaction proceeds under solvent-free conditions and tolerates even a bromo substituent.

Cover Picture: Oxidative Cyclization Reaction of 2-Aryl-Substituted Cinnamates To Form Phenanthrene Carboxylates by Using MoCl5 (Chem. Eur. J. 39/2014)

Cover Picture: Bis(2,2′‐biphenoxy)borates for Electrochemical Double‐Layer Capacitor Electrolytes (Chem. Eur. J. 11/2011)

Synthesis of 9,9′-Spirobifluorenes and 4,5-Diaza-9,9′-spirobifluorenes and Their Application as Affinity Materials for Quartz Crystal Microbalances

Two different classes of aza analogues of 9,9'-spirobifluorenes have been synthesized. These were obtained by either furnishing the spirobifluorene with additional pyridyl moieties or by installing the aza function directly into the spirobifluorene core. These structurally rigid compounds were then evaluated as affinity materials for quartz crystal microbalances and proved to be highly potent for the detection of volatile organic compounds.

ChemInform Abstract: Molybdenum Pentachloride Mediated Synthesis of Spirocyclic Compounds by Intramolecular Oxidative Coupling.

Oxidative treatment of 4-methoxy substituted 2-aryl cinnamates leads to an dealkylative C—C coupling and gives access to spirocyclic compounds.

Influencing the Self‐Sorting Behavior of [2.2]Paracyclophane‐Based Ligands by Introducing Isostructural Binding Motifs

Abstract Two isostructural ligands with either nitrile (Lnit) or isonitrile (Liso) moieties directly connected to a [2.2]paracyclophane backbone with pseudo‐meta substitution pattern have been synthesized. The ligand itself (Lnit) or its precursors (Liso) were resolved by HPLC on a chiral stationary phase and the absolute configuration of the isolated enantiomers was assigned by XRD analysis and/or by comparison of quantum‐chemical simulated and experimental electronic circular dichroism (ECD) spectra. Surprisingly, the resulting metallosupramolecular aggregates formed in solution upon coordination of [(dppp)Pd(OTf)2] differ in their composition: whereas Lnit forms dinuclear complexes, Liso…

Installation of Amine Moieties into a Polycyclic Anodic Product Derived from 2,4-Dimethylphenol

When 2,4-dimethylphenol is anodically treated, a dehydrotetramer with four contiguous stereocentres is readily obtained on a multi-gram scale. The substitution of a 2,4-dimethyl-phenoxy fragment by several amines was demonstrated, and the best results were obtained with primary amines. Optically pure α-chiral aliphatic amines yield diastereomeric mixtures that can be separated in most cases. The basic amine causes a partial hemiketal-opening of the bisbenzofuran moiety leading to an equilibrium within an α,β-unsaturated cyclohexenone. This dynamic behaviour occurs on the time scale of NMR spectroscopy and is also found by X-ray analysis providing a consistent picture.

Influencing the self‐sorting behavior of [2.2]paracyclophane based ligands by introducing isostructural binding motifs

Two isostructural ligands with either nitrile ( L nit ) or isonitrile ( L iso ) moieties directly connected to a [2.2]paracyclophane backbone with pseudo‐meta substitution pattern have been synthesized. The ligand itself ( L nit ) or its precursors ( L iso ) were resolved via HPLC on a chiral stationary phase and the absolute configuration of the isolated enantiomers was assigned by XRD analysis and/or by comparison of quantum‐chemical simulated and experimental ECD‐spectra. Surprisingly, the resulting metallosupramolecular aggregates formed in solution upon coordination of [(dppp)Pd(OTf) 2 ] differ in their composition: whereas L nit forms dinuclear complexes L iso exclusively forms trinuc…

Synthesis of Highly Fluorinated 2,2′-Biphenols and 2,2′-Bisanisoles

Multiply fluorine-substituted iodo anisoles are efficiently coupled in an Ullmann-type reaction to provide the corresponding bisanisoles. The coupling is selective and even tolerates bromo moieties. Subsequent deprotection of hydroxy groups gives access to highly fluorinated biphenols.

Diversity-Oriented Synthesis of Polycyclic Scaffolds by Modification of an Anodic Product Derived from 2,4-Dimethylphenol

Highly selective electrosynthesis of biphenols on graphite electrodes in fluorinated media.

The direct and selective phenol coupling reaction that provides biphenols still represents a challenge in organic synthesis. The recently developed electrosynthesis on boron-doped diamond anodes with fluorinated additives was developed further to allow the application to less-expensive electrodes and fluorinated media. This advanced protocol allows the highly selective anodic phenol coupling reaction on graphite with a broad scope.

Chiral Self-Sorting of trans-Chelating Chiral Ligands upon Formation of PdII Complexes

Invited for the cover of this issue is the group of Arne Lutzen at the University of Bonn, Germany. The cover image shows two dissymmetric bis(3-pyridyl) ligands based on a planar chiral pseudo-ortho-disubstituted [2.2]paracyclophane scaffold. Upon forming a mononuclear [ML2] complex with palladium(II) ions, these ligands act in a trans-chelating manner and undergo complete chiral self-sorting.

Stepwise Construction of Heterobimetallic Cages by an Extended Molecular Library Approach.

Two novel heterobimetallic complexes, a trigonal-bipyramidal and a cubic one, have been synthesized and characterized using the same C3-symmetric metalloligand, prepared by a simple subcomponent self-assembly strategy. Adopting the molecular library approach, we chose a mononuclear, preorganized iron(II) complex as the metalloligand capable of self-assembly into a trigonal-bipyramidal or a cubic aggregate upon coordination to cis-protected C2-symmetric palladium(II) or unprotected tetravalent palladium(II) ions, respectively. The trigonal-bipyramidal complex was characterized by NMR and UV–vis spectroscopy, electrospray ionization mass spectrometry (ESI-MS), and single-crystal X-ray diffrac…

CCDC 1415863: Experimental Crystal Structure Determination

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CCDC 986176: Experimental Crystal Structure Determination

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CCDC 1573413: Experimental Crystal Structure Determination

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CCDC 986175: Experimental Crystal Structure Determination

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CCDC 945021: Experimental Crystal Structure Determination

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CCDC 1573412: Experimental Crystal Structure Determination

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CCDC 1573312: Experimental Crystal Structure Determination

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CCDC 1824417: Experimental Crystal Structure Determination

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CCDC 1824416: Experimental Crystal Structure Determination

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CCDC 1955599: Experimental Crystal Structure Determination

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CCDC 945019: Experimental Crystal Structure Determination

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CCDC 804368: Experimental Crystal Structure Determination

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CCDC 1573313: Experimental Crystal Structure Determination

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CCDC 986177: Experimental Crystal Structure Determination

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CCDC 1415860: Experimental Crystal Structure Determination

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CCDC 1415861: Experimental Crystal Structure Determination

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CCDC 1550913: Experimental Crystal Structure Determination

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CCDC 1573410: Experimental Crystal Structure Determination

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CCDC 1427184: Experimental Crystal Structure Determination

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CCDC 986178: Experimental Crystal Structure Determination

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CCDC 1573414: Experimental Crystal Structure Determination

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CCDC 941094: Experimental Crystal Structure Determination

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CCDC 945020: Experimental Crystal Structure Determination

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CCDC 941095: Experimental Crystal Structure Determination

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CCDC 1955601: Experimental Crystal Structure Determination

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CCDC 1415862: Experimental Crystal Structure Determination

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CCDC 1575238: Experimental Crystal Structure Determination

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CCDC 1573411: Experimental Crystal Structure Determination

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CCDC 1427185: Experimental Crystal Structure Determination

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CCDC 1419863: Experimental Crystal Structure Determination

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CCDC 1955600: Experimental Crystal Structure Determination

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CCDC 804367: Experimental Crystal Structure Determination

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