Technical University of Dortmund

About: Technical University of Dortmund is a education organization based out in Dortmund, Nordrhein-Westfalen, Germany. It is known for research contribution in the topics: Context (language use) & Large Hadron Collider. The organization has 13028 authors who have published 27666 publications receiving 615557 citations. The organization is also known as: Dortmund University & University of Dortmund.

Colloquium : Protecting quantum information against environmental noise

Abstract: Quantum-mechanical systems retain their properties so long as the phase of quantum superpositions evolve stably over time. Contact with an environment can disrupt this phase evolution. But for environments that do not exchange energy with the quantum system, strategies exist where the controlled driving of the system can recover or maintain the quantum phase. This Colloquium surveys the host of techniques that are available to ``refocus'' the phase when disturbed by various forms of classical or quantum environment. While the first such techniques were developed long ago, ideas from quantum information theory have introduced new strategies for accomplishing this goal.

General Enantioselective C-H Activation with Efficiently Tunable Cyclopentadienyl Ligands.

Abstract: Cyclopentadienyl (Cp) ligands enable efficient steering of various transition-metal-catalyzed transformations, in particular enantioselective C−H activation. Currently only few chiral Cp ligands are available. Therefore, a conceptually general approach to chiral Cp ligand discovery would be invaluable as it would enable the discovery of applicable Cp ligands and to efficiently and rapidly vary and tune their structures. Herein, we describe the three-step gram-scale synthesis of a structurally diverse and widely applicable chiral Cp ligand collection (JasCp ligands) with highly variable and adjustable structures. Their modular nature and their amenability to rapid structure variation enabled the efficient discovery of ligands for three enantioselective RhIII-catalyzed C−H activation reactions, including one unprecedented transformation. This novel approach should enable the discovery of efficient chiral Cp ligands for various further enantioselective transformations.

One-pot reactions accelerate the synthesis of active pharmaceutical ingredients.

Abstract: The word “Eintopf” (lit. Engl. one pot) is used generically in the German language to describe a simplistic technique of cooking all the ingredients of a meal in a single pot. It has also found its way into the chemical language as “one-pot reaction” or “one-pot process”, in particular to emphasize that a sequence of chemical transformations is run in a single flask. Similar to the cook in the kitchen, synthetic chemists strive to save time and resources by avoiding purifications between individual steps within a multistep synthesis, thus minimizing the transfer of material between vessels. In the strategic planning stage, several concepts are introduced so that alternative synthetic routes can be validated. Thus, the comparison of easy-to-measure parameters serves as a yardstick to identify the most economic approach. In atom economy, the efficiency quotient of the simple reaction A + B!C + D is derived from the molecular weight of the desired product C divided by the combined molecular weight of the reactants (A+B). For 100% atom efficiency, D must be non-existent, that is, all the atoms in A and B end up in the product C. Such “ideal” reactions include the Diels–Alder reaction and catalytic hydrogenations, whereas the Gabriel synthesis (phthalimide used as the synthetic equivalent of ammonia) and Hantzsch ester hydrogenations (with dihydropyridines used as dihydrogen equivalents) are examples of reactions with lower atom efficiency. The quality and quantity of the synthetic steps (step economy) as well as the changes in the oxidation state (redox economy) have been suggested as decisive parameters for a comparative analysis of the multistep syntheses. Clarke et al. recently added pot economy to the above list, with the ultimate aim “to complete an entire multi-step, multi-reaction synthesis in a single pot”. Now, this ambitious goal has been achieved by the Hayashi research group in their one-pot total synthesis of the dipeptidylpeptidase IV (DPP4) selective inhibitor ABT-341 (Scheme 1). Before discussing the synthesis, it is important to outline the development of the enabling methodology. It is well understood that domino reactions and multicomponent reactions are the silver bullets for the rapid construction of complex molecular scaffolds in an economic fashion, with built-in step and pot economy. In this direction, organocatalysis has opened up new vistas by allowing the merger of different modes of activation under the typically mild reaction conditions. The triple cascade of Enders et al. was an early example which unleashed the full potential of organocatalytic domino reactions. The cyclohexene derivatives obtained by Enders et al. (for example, 1) bear a remarkable resemblance to the carbocyclic core of ( )-oseltamivir (Tamiflu) and ABT-341 (Scheme 1). In a classical one-pot reaction, all the reagents are added sequentially to the reaction flask, followed by work-up and purification. Hayashi and co-workers have disclosed a strategy called an “uninterrupted sequence of reactions”. In contrast to the classical one-pot reaction or telescoped synthesis, where the number of different operations (extractions, distillations) is minimized, the removal of volatiles from the reaction vessel by distillation is explicitly allowed. An initial application, in their pursuit to minimize the transfer of material between flasks, was the development of an organocatalytic synthesis of ( )-oseltamivir. The first published synthesis, which consisted of three one-pot reactions, was later shortened to two consecutive one-pot processes (Scheme 2). In the design of an uninterrupted sequence of reactions it is advantageous to use low-boiling solvents, which are easily removed under high vacuum, and reagents that are Scheme 1. A cyclohexene derivative 1 from Enders’ triple cascade, ( )-oseltamivir (Tamiflu), and ABT-341.

Electron and photon performance measurements with the ATLAS detector using the 2015-2017 LHC proton-proton collision data

Abstract: This paper describes the reconstruction of electrons and photons with the ATLAS detector, employed for measurements and searches exploiting the complete LHC Run 2 dataset. An improved energy clustering algorithm is introduced, and its implications for the measurement and identification of prompt electrons and photons are discussed in detail. Corrections and calibrations that affect performance, including energy calibration, identification and isolation efficiencies, and the measurement of the charge of reconstructed electron candidates are determined using up to 81 fb−1 of proton-proton collision data collected at √s=13 TeV between 2015 and 2017.