Publications by authors named "Peter Langer"

Novel π-expanded and N-doped fluoranthenes were synthesized and thoroughly investigated. These eight unsubstituted compounds are obtained in a multistep synthesis with CH activation as the last key reaction step. The structures vary in their position of π-expansion on the fluoranthene scaffold and the location of the pyridinic nitrogen atom.

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Article Synopsis
  • A new method for creating enantiomerically enriched (S)-α-aminopropionic acid derivatives was developed using a reaction called Cu(I) catalyzed [3 + 2] cycloaddition, which combines azides with alkynes.
  • The process started with a specific nickel complex and involved several key chemical components, including Schiff bases and phenyl azides.
  • The absolute configuration and purity of the resulting amino acids were confirmed through advanced techniques like circular dichroism and chiral HPLC analysis, leading to the successful synthesis of seven new non-proteinogenic (S)-α-amino acids.
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Indigo, indirubin, and isoindigo derivatives have been used for centuries as pigments. Since the 1990s, a new aspect of the chemistry of this type of compounds is their activity against various types of cancer. -Glycosides of indigo, indirubin, and isoindigo, blue, red, and yellow sugars, turned out to be of special interest because of their high cancerostatic activity and structural novelty.

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Article Synopsis
  • The study describes the creation of polycyclic uracil derivatives using a combination of palladium-catalyzed cross-coupling reactions and cycloisomerization with Brønsted acids.
  • This new method effectively accommodates a variety of functional groups, resulting in product yields ranging from moderate to nearly complete.
  • The researchers also examined how different functional groups affect the optical properties of the final compounds using UV-vis and fluorescence spectroscopy.
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Filtering face piece (FFP) masks according to EN 149 are essential components of personal protective equipment against biological agents from an occupational health and hospital hygiene perspective. Therefore, shortages due to increased demand or supply bottlenecks can lead to staff threats due to the risk of infection. To determine whether FFP masks could be made reusable in a hospital setting, a thermal reprocessing concept (steam at 105 °C with a holding phase of 10 min) was evaluated in a bed reprocessing chamber.

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The incorporation of heteroatoms within polycyclic aromatic compounds has gained significant interest due to its potential to effectively alter the inherent physicochemical properties of compounds without the need for profound structural changes. We herein report the development of a modular synthesis of hitherto unknown thienonaphtho[]pyridines and thienonaphtho[]quinolines in very good yields by Brønsted acid mediated cycloisomerization, permitting selective access to two isomeric products that are isoelectronic to the parent dibenzopyrene. The photophysical and electrochemical properties of the desired compounds were extensively studied and further complemented by DFT calculations.

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Triarylamines are frequently employed as electron donor functional groups in a variety of organic electronic materials. We herein report the synthesis and in-depth characterisation of aza-analogues of fully bridged triarylamines, consisting of 5-, 6- and 7-membered rings. The impact of nitrogen doping and π-extension on the structural, electronic and optical-properties of these contorted heteroaromatic PAHs is thoroughly investigated and paves the way for an improved understanding of the structure-property relationships.

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Given the health benefits of carotenoids, it is crucial to evaluate their levels in patients undergoing malabsorptive procedures like one anastomosis gastric bypass (OAGB). This study aimed to assess serum carotenoid levels before and 6 months following OAGB. Prospectively collected data from patients who underwent primary OAGB were analyzed.

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Domino reactions of chromones with activated carbonyl compounds, such as dimethyl acetone-1,3-dicarboxylate and 1,3-diphenylacetone, and with 1,3-bis(silyloxy)-1,3-butadienes, electroneutral equivalents of 1,3-dicarbonyl dianions, allow for a convenient synthesis of a great variety of products. The regioselectivity and course of the reaction depends of the substituent located at carbon C3 of the chromone moiety and also on the type of nucleophile employed.

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Three bis- or tris-brominated 2-trifluoromethylquinolines have been successfully applied in palladium-catalysed Sonogashira reactions, leading to several examples of alkynylated quinolines in good to excellent yields. Optical properties of selected products have been studied by steady state absorption and fluorescence spectroscopy which give insights of the influence of the substitution pattern and of the type of substituents on the optical properties.

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Ullazines and their π-expanded derivatives have gained much attention as active components in various applications, such as in organic photovoltaic cells or as photosensitizers for CO photoreduction. Here, we report the divergent synthesis of functionalized diazaullazines by means of two different domino-reactions consisting of either a Povarov/cycloisomerization or alkyne-carbonyl metathesis/cycloisomerization protocol. The corresponding quinolino-diazaullazine and benzoyl-diazaullazine derivatives were obtained in moderate to good yields.

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The development of a new and straightforward chemoselective method for the synthesis of uracil-based structures by combining Suzuki-Miyaura and Sonogashira-Hagihara cross-coupling is reported. The methodology was applied to synthesize a series of novel compounds. The tolerance of the combination of different functional groups was tested.

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Background: Multiple myeloma (MM) is a haematological malignancy that is characterised by proliferation of malignant plasma cells in the bone marrow. For adults ineligible to receive high-dose chemotherapy and autologous stem cell transplant, the recommended treatment combinations in first-line therapy generally consist of combinations of alkylating agents, immunomodulatory drugs, and proteasome inhibitors. Daratumumab is a CD38-targeting, human IgG1k monoclonal antibody recently developed and approved for the treatment of people diagnosed with MM.

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Doping and extension of polycyclic aromatic hydrocarbons (PAHs) by simple and efficient synthetic methods is of increased demand for the development of novel and improved organic electronics. Diarylindolizino[6,5,4,3-]quinolino[2,3-][1,6]naphthyridines (quinolino-azaullazines) were prepared by combination of Pd catalyzed cross-coupling with Povarov and cycloisomerisation reactions. The products contain an electron-rich ullazine and an electron-poor quinoline moiety and show intramolecular charge transfer properties that can be tuned by the substitution pattern.

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A series of 4- and 10-benzoyl-1-azapyrenes were prepared by a combination of Pd-catalyzed cross-coupling reactions and Brønsted-acid-mediated alkyne-carbonyl-metathesis (ACM). The photophysical and electrochemical properties of the products were studied and compared to theoretical results.

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Hitherto unknown 5,8-substituted-pyrimido[4,5,6-]pyrrolo[2,1,5-]quinolizines (5,7-diazaullazines) were prepared by a three-step synthesis via Clauson-Kaas, Sonogashira, and cycloisomerization reactions with diverse functionalization. The properties, including cyclovoltammetry and UV-vis and fluorescence spectroscopy, as well as solvatochromism, were studied for selected derivatives and supported by density functional theory calculations. Results were compared in detail with previously reported 5- and 6-azaullazines, and the impact of introduced nitrogen atoms was analyzed.

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Thiazolopyridines are a highly relevant class of small molecules, which have previously shown a wide range of biological activities. Besides their anti-tubercular, anti-microbial and anti-viral activities, they also show anti-cancerogenic properties, and play a role as inhibitors of cancer-related proteins. Herein, the biological effects of the thiazolopyridine AV25R, a novel small molecule with unknown biological effects, were characterized.

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The considerable need for novel polyaromatic hydrocarbons (PAHs) for applications in the area of organic electronics remains unchanged. Diacenaphthopyrene represents a new PAH consisting of two acenaphthylene units connected by a pyrene bridge. The system is built up by Pd-catalyzed cross-coupling, followed by acid catalyzed cyclosiomerization to generate the pyrene moiety.

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This report describes a one-pot multi-step procedure to obtain double azahelicenes via nucleophilic fluorine substitution of 2,2-di(2-bromophenyl)-1,1-difluoroalkenes and palladium-catalysed ring closing reaction. The developed synthesis approach allows easy diversification of substituents at all four fragments of the obtained X-shaped aza[4,6]helicene entity. Yields range from 20 % to 60 % among 12 product examples.

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[1,8]-Naphthyridine derivatives have been reported to possess important biological activities and may serve as attractive pharmacophores in the drug discovery process. [1,8]-Naphthyridine derivatives (1a-1l) were evaluated for inhibitory potential for isozymes of carbonic anhydrase (CA) and alkaline phosphatase (ALP). CAs have been reported to carry out reversible hydration of CO into HCO, secretion of electrolytes, acid-base regulation, bone resorption, calcification, and biosynthetic reactions.

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Skin cancer is the most common malignant disease worldwide and, therefore, also poses a challenge from a pharmacotherapeutic perspective. Derivatives of indirubin are an interesting option in this context. In the present study, the effects of 3-[3'-oxo-benzo[]thiophen-2'-()-ylidene]-1-(β-d-glucopyranosyl)-oxindole (KD87), a thia-analogous indirubin -glycoside, on the viability and mitochondrial properties of melanoma (A375) and squamous cell carcinoma cells (A431) of the skin were investigated.

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A new and convenient synthesis of aryl-substituted naphtho[2,1-]azulenes by the combination of Suzuki-Miyaura, Sonogashira, and cycloisomerization reactions is reported. The methodology was applied to the synthesis of hitherto unknown azuleno[1,2-]quinolines, cyclohepta[1,2]indeno[4,5-]thiophenes, and cyclohepta[1,2]indeno[4,5-]thiophenes. The impact of different fused-heterocyclic rings on the photophysical and electrochemical properties of these azulene derivatives was studied by experimental and theoretical methods and hence provides a rationale for the preparation of novel azulene derivatives with improved properties for application as organic materials.

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5-Azaullazines, indolizino[6,5,4,3-][1,5]naphthyridines, and their benzo-fused analogues were prepared in three steps by combination of Pd catalyzed cross-coupling reactions with Brønsted acid mediated cycloisomerisations. The reaction tolerates various substitution patterns and functional groups and proceeds in high yields. Optical and electrochemical properties of selected products were studied experimentally and by DFT calculations.

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Introduction: Skin cancer is often fatal, which motivates new therapy avenues. Recent advances in cancer treatment are indicative of the importance of combination treatments in oncology. Previous studies have identified small molecule-based therapies and redox-based technologies, including photodynamic therapy or medical gas plasma, as promising candidates to target skin cancer.

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Benzo[h]imidazo[1,2-a]quinolines and 1,2a-diazadibenzo[cd,f]azulenes were prepared from a common intermediate by regioselective cycloisomerization reactions. The selectivity was controlled by the choice of Brønsted acid and solvent. The optical and electrochemical properties of the products were studied by UV/vis, fluorescence, and cyclovoltammetric measurements.

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