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Toward a conversion of aldehydes into arenes, we designed a sequence involving the initial reaction of an aldehyde to give a fulvene, followed by photochemical and platinum‐catalyzed rearrangements into a Dewar benzene derivative, which finally isomerizes into the targeted arene. While computational studies support the plausibility of this route, we found that fulvene irradiation resulted in an unexpected isomerization into a spiro[2.4]heptadiene. This unusual photorearrangement has been investigated mechanistically and provides access to a variety of spiro[2.4]heptadienes with different substituents. [ABSTRACT FROM AUTHOR]

Um Aldehyde in Arene zu überführen, haben wir eine Sequenz entworfen, bei der ein Aldehyd zunächst zu einem Fulven umgesetzt wird. Daraufhin folgen photochemische und platinkatalysierte Umlagerungen zu einem Dewar‐Benzol‐Derivat, welches schließlich in das gewünschte Aren isomerisiert. Obwohl theoretische Berechnungen die Plausibilität dieses Weges nahelegen, stellten wir experimentell fest, dass die Fulven‐Bestrahlung zu einer unerwarteten Isomerisierung in ein Spiro[2.4]heptadien führt. Diese ungewöhnliche Photoumlagerung wurde mechanistisch untersucht und ermöglicht den Zugang zu verschiedenen Spiro[2.4]heptadienen mit unterschiedlichen Substituenten. [ABSTRACT FROM AUTHOR]

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The article offers a report from an August 20-21, 2013 conference in Augsburg, Germany on social sciences and the humanities. Topics of presentations given included discourse theoretical analysis of language, the amalgamation of contradictory social theories, and alleged contradictions in political participation.

In the paper [3] the authors have examined functions of the Baire class 1, where the domain and the range were metric spaces. The ε - δ characterization of such functions has been proved. In this note we examine, if replacing of the condition from [3] by it's stronger version can lead us to the characterization of some subclass of B1 on the interval [0, 1]. [ABSTRACT FROM AUTHOR]

In the paper of Lee et al. an equivalent condition for a function ƒ to be of the first Baire class has been established. This condition is of an ε -- δ type, similarly as in Cauchy's definition of continuity of a function. In the first part of this paper we examine a problem whether it is possible to obtain other classes of functions by further modifications of the above condition. It turns out that, in some sense, the answer is negative. In the second part we consider a topological version of the condition of Lee et al. [ABSTRACT FROM AUTHOR]

Electron-rich heteroaromatic imidodiphosphorimidates (IDPis) catalyze the asymmetric Pictet-Spengler reaction of N -carbamoyl-β-arylethylamines with high stereochemical precision. This particular class of catalysts furthermore provides a vital rate enhancement compared to related Brønsted acids. Here we present experimental studies on the underlying reaction kinetics that shed light on the specific origins of rate acceleration. Analysis of Hammett plots, kinetic isotope effects, reaction orders, Eyring plots, and isotopic scrambling experiments, allowed us to gather insights into the molecular interactions between the chiral Brønsted acid and catalytically formed intermediates. Based on rigorously determined p K a values as well as the experimental evidence, we propose that attractive intermolecular forces offered by electron-rich π-surfaces of the chiral counteranion enthalpically stabilize cationic intermediates and transition states by way of cation-π interactions. This view is furthermore supported by in-depth density functional theory calculations. Our deepened understanding of the reaction mechanism allowed us to develop a method for accessing 1-aryltetrahydroisoquinolines from aromatic dimethyl acetals, a substrate class that was thus far inaccessible via catalytic asymmetric Pictet-Spengler reactions.

Since the first reports some three decades ago, the chemistry of pincer metal complexes has seen a tremendous development with impact on materials chemistry, supramolecular chemistry, bioorganometallics, and, presumably most significantly, on (catalytic) bond making and breaking processes. The remarkable progress is due to a large extent to the well-defined nature and tunability of the pincer ligand which allows the reactivity of the metal center to be modified and eventually tailored to specific needs. This Perspective summarizes the achievements in employing pincer complexes for mediating and catalyzing the cleavage of typically unreactive bonds such as C-H, C-C, C-E, and E-H bonds, arguably one of the most spectacular applications of pincer chemistry., (This journal is © The Royal Society of Chemistry 2011)