Search results for: Hans-Achim Wagenknecht

Items from 1 to 20 out of 67 results

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The Concept of Photozymes: Short Peptides with Photoredox Catalytic Activity for Nucleophilic Additions to α‐Phenyl Styrenes

Daniel Sack, Hans‐Achim Wagenknecht

European Journal of Organic Chemistry > 2021 > 46 > 6400 - 6407

Conventional photoredox catalytic additions of alcohols to olefins require additives, like thiophenol, to promote back electron transfer. The concept of “photozymes” assumes that forward and backward electron transfer steps in a photoredox catalytic cycle are controllable by substrate binding to photocatalytically active peptides. Accordingly, we synthesized a short tripeptide modified with 1,7‐dicyano‐perylene‐3,4...

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Fast and Efficient Postsynthetic DNA Labeling in Cells by Means of Strain‐Promoted Sydnone‐Alkyne Cycloadditions

Katja Krell, Bastian Pfeuffer, Franziska Rönicke, Zoeisha S. Chinoy, more

Chemistry – A European Journal > 27 > 65 > 16093 - 16097

Sydnones are highly stable mesoionic 1,3‐dipoles that react with cyclooctynes through strain‐promoted sydnone‐alkyne cycloaddition (SPSAC). Although sydnones have been shown to be valuable bioorthogonal chemical reporters for the labeling of proteins and complex glycans, nucleic acids have not yet been tagged by SPSAC. Evaluation of SPSAC kinetics with model substrates showed fast reactions with cyclooctyne...

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Cover Feature: Fast and Efficient Postsynthetic DNA Labeling in Cells by Means of Strain‐Promoted Sydnone‐Alkyne Cycloadditions (Chem. Eur. J. 65/2021)

Katja Krell, Bastian Pfeuffer, Franziska Rönicke, Zoeisha S. Chinoy, more

Chemistry – A European Journal > 27 > 65 > 16058 - 16058

DNA strands, modified with the novel bioorthogonal reporter sydnone, undergo fast and efficient labeling with cyclooctyne–dye conjugates, both in vitro and in HeLa cells. These results show that sydnones are versatile bioorthogonal tags and have the premise to become essential tools for tracking DNA and potentially RNA in living cells. More information can be found in the Communication by F. Friscourt,...

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Cover Feature: Photoredox Catalytic Pentafluorosulfanylative Domino Cyclization of α‐Substituted Alkenes to Oxaheterocycles by Using SF₆ (Chem. Eur. J. 31/2021)

David Rombach, Bernhard Birenheide, Hans‐Achim Wagenknecht

Chemistry – A European Journal > 27 > 31 > 8059 - 8059

Let's play dominoes with SF₆: The photoredox catalytic activation of SF₆ in the presence of a‐substituted styrenes and alkynols initiates a reaction sequence that consecutively forms a C−O bond, a C−C bond and a C−SF₅ bond, one after another. Finally, this domino reaction yields pentafluorosulfanylated oxygen‐containing heterocycles in a single step. These new compounds bear a complex structure and...

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Photoredox Catalytic Pentafluorosulfanylative Domino Cyclization of α‐Substituted Alkenes to Oxaheterocycles by Using SF₆

David Rombach, Bernhard Birenheide, Hans‐Achim Wagenknecht

Chemistry – A European Journal > 27 > 31 > 8088 - 8093

Virtually inert sulfur hexafluoride becomes a precious pentafluorosulfanylation agent, if properly activated by photoredox catalysis, to access α‐fluoro and α‐alkoxy SF₅‐compounds. This advanced protocol converts SF₆ in the presence of alkynols as bifunctional C−C‐ and C−O‐bond forming reagents directly into pentafluorosulfanylated oxygen‐containing heterocycles in a single step from α‐substituted...

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Nucleophilic Alkoxylations of Unactivated Alkyl Olefins and α‐Methyl Styrene by Photoredox Catalysis

Fabienne Seyfert, Mathis Mitha, Hans‐Achim Wagenknecht

European Journal of Organic Chemistry > 2021 > 5 > 773 - 776

N,N‐diisobutylaminophenyl‐phenothiazine is a strongly reducing catalyst that allows – for the first time – the photoredox catalytic addition of alcohols to alkyl olefins as non‐activated substrates to products with Markovnikov orientation. The irradiation at 365 nm does not require any additional reagent. Using α‐methyl styrene as activated substrate we additionally show that this photoredox catalytic...

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Front Cover: Nucleophilic Alkoxylations of Unactivated Alkyl Olefins and α‐Methyl Styrene by Photoredox Catalysis (Eur. J. Org. Chem. 5/2021)

Fabienne Seyfert, Mathis Mitha, Hans‐Achim Wagenknecht

European Journal of Organic Chemistry > 2021 > 5 > 709 - 709

The Front Cover shows an illustration how N‐phenylphenothiazines can be used as photoredox catalysts for the photoreduction of alkylated olefins and subsequent nucleophilic addition by alcohols. Compared to conventional photoredox catalyst, such as [Ru(bpy)3]2+ and eosin Y, N‐phenylphenothiazine have significantly more reducing power that is crucial for the photoinduced electron transfer to alkylated...

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Wie weit wandert Energie in der DNA und verursacht Schäden? Nachweis des langreichweitigen Photoschadens in DNA

Arthur Kuhlmann, Larissa Bihr, Hans‐Achim Wagenknecht

Angewandte Chemie > 132 > 40 > 17530 - 17535

Eine neue DNA‐Architektur ermöglicht zu untersuchen, wie weit Energie in DNA wandert und Cyclobutanpyrimidindimere (CPD) als Photoschäden, die Hautkrebs verursachen, bildet. Das Nucleosid des 3‐Methoxyxanthons erlaubt die ortsselektive Injektion von Lichtenergie in die DNA. Die designierte CPD‐Stelle, der die Phosphodiesterbindung fehlt, kann in definierten Distanzen platziert werden. Die CPD‐Bildung...

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Frontispiz: Wie weit wandert Energie in der DNA und verursacht Schäden? Nachweis des langreichweitigen Photoschadens in DNA

Arthur Kuhlmann, Larissa Bihr, Hans‐Achim Wagenknecht

Angewandte Chemie > 132 > 40 > n/a - n/a

DNA‐Läsionen In der Zuschrift auf S. 17530 berichten H.‐A. Wagenknecht et al. über eine neue DNA‐Architektur, mit der die Frage untersucht wird, wie weit Energie in DNA migriert und Cyclobutanpyrimidin‐Dimere als Hautkrebs verursachende Photoschäden bildet.

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How Far Does Energy Migrate in DNA and Cause Damage? Evidence for Long‐Range Photodamage to DNA

Arthur Kuhlmann, Larissa Bihr, Hans‐Achim Wagenknecht

Angewandte Chemie International Edition > 59 > 40 > 17378 - 17382

A new DNA architecture addresses the question, how far energy migrates in DNA and forms cyclobutane pyrimidine dimers (CPDs) as photodamages causing skin cancer. The 3‐methoxyxanthone nucleoside allows site‐selective photoenergy injection into DNA. The designated CPD site lacks the phosphodiester bond and can be placed in defined distances. The CPD formation links two oligonucleotides together and...

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Frontispiece: How Far Does Energy Migrate in DNA and Cause Damage? Evidence for Long‐Range Photodamage to DNA

Arthur Kuhlmann, Larissa Bihr, Hans‐Achim Wagenknecht

Angewandte Chemie International Edition > 59 > 40 > n/a - n/a

DNA Lesions In their Communication on page 17378, H.‐A. Wagenknecht et al. report a new DNA architecture to address the question how far energy migrates in DNA and forms cyclobutane pyrimidine dimers as photodamages causing skin cancer.

article

Photoredox Catalytic α‐Alkoxypentafluorosulfanylation of α‐Methyl‐ and α‐Phenylstyrene Using SF₆

David Rombach, Hans‐Achim Wagenknecht

Angewandte Chemie International Edition > 59 > 1 > 300 - 303

SF₆ was applied as pentafluorosulfanylation reagent to prepare ethers with a vicinal SF₅ substituent through a one‐step method involving photoredox catalysis. This method shows a broad substrate scope with respect to applicable alcohols for the conversion of α‐methyl and α‐phenyl styrenes. The products bear a new structural motif with two functional groups installed in one step. The alkoxy group allows...

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Photoredoxkatalytische α‐Alkoxypentafluorosulfanylierung von α‐Methyl‐ und α‐Phenylstyrol mithilfe von SF₆

David Rombach, Hans‐Achim Wagenknecht

Angewandte Chemie > 132 > 1 > 306 - 310

SF₆ wurde als Pentafluorosulfanylierungsreagenz in der Photoredoxkatalyse verwendet, um über ein Einstufenprotokoll Ether mit vicinalem SF₅‐Substituent herzustellen. Diese Methode weist ein breites Substratspektrum bei den verwendbaren Alkoholen für die Umsetzung von α‐Methyl‐ und α‐Phenylstyrol auf. Die Produkte enthalten ein neues Strukturmotiv mit zwei funktionellen Gruppen, das in einem Reaktionsschritt...

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Substitution of Metallocenes with [2.2]Paracyclophane to Enable Confocal Microscopy Imaging in Living Cells

Joanna Skiba, Claudia Schmidt, Petra Lippmann, Philipp Ensslen, more

European Journal of Inorganic Chemistry > 2019 > 20 > 2565 - 2565

article

Programmable and Sequence‐Selective Supramolecular Assembly of Two Different Chromophores along DNA Templates

Robert Hofsäß, Stephan Sinn, Frank Biedermann, Hans‐Achim Wagenknecht

Chemistry – A European Journal > 24 > 61 > 16257 - 16261

The templated self‐assembly of two different chromophores attached to the same binding motif gives oligomers of statistical mixtures without any control on the resulting chromophore sequence. The first self‐assembled bichromophore system is reported, in which the resulting chromophore sequence is simply governed by the DNA template. A new ethynylpyrene‐diaminopurine 2′‐deoxynucleoside was combined...

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Proline‐Rich Short Peptides with Photocatalytic Activity for the Nucleophilic Addition of Methanol to Phenylethylenes

Sergej Hermann, Daniel Sack, Hans‐Achim Wagenknecht

European Journal of Organic Chemistry > 2018 > 19 > 2204 - 2207

Short proline‐rich peptides were synthesized and modified with 1‐(N,N‐dimethylamino)pyrene by copper(I)‐catalyzed cycloaddition. They perform photoredox catalysis of the nucleophilic addition of methanol to 1,1‐diphenylethylene derivatives into products with Markovnikov orientation. The common additive triethylamine is avoided because forward and backward electron transfer is controlled by substrate...

article

Light-induced functions in DNA

Ulrike Reisacher, Linda Antusch, Robert Hofsäß, Christian Schwechheimer, more

Current Opinion in Chemical Biology > 2017 > 40 > C > 119-126

The chemical toolbox for synthetic modification by nucleotide building blocks and postsynthetic methods delivers light-induced functions to DNA in great variety and allows not only to initiate photoinduced processes but additionally the temporal and spatial control of these artificial functions. Herein, selected light-induced artificial functions in DNA are briefly summarized. This includes the postsynthetic...

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Synthesis of N,N‐dimethylaminopyrene‐modified short peptides for chemical photocatalysis

Sergej Hermann, Hans‐Achim Wagenknecht

Journal of Peptide Science > 23 > 7-8 > 563 - 566

The synthesis of peptide‐based photocatalysts that use 1‐N,N‐dimethylaminopyrene as chromophore and their application in photocatalysis is reported. The copper(I)‐catalyzed alkyne‐azide cycloaddition was applied as key step to prepare the peptide–pyrene conjugates in quantitative yields for different short peptide sequences. The photocatalysts were evaluated for the nucleophilic addition of methanol...

article

Molecular movement in the Arabidopsis thaliana female gametophyte

Robert M. Erdmann, Anja Hoffmann, Heidi-Kristin Walter, Hans-Achim Wagenknecht, more

Plant Reproduction > 2017 > 30 > 3 > 141-146

Key messageSize limits on molecular movement among female gametes. Abstract Cellular decisions can be influenced by information communicated from neighboring cells. Communication can occur via signaling or through the direct transfer of molecules. Movement of RNAs and proteins has frequently been observed among symplastically connected plant cells. In flowering plants, the female gametes, the egg...

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Elucidation of the Dexter‐Type Energy Transfer in DNA by Thymine–Thymine Dimer Formation Using Photosensitizers as Artificial Nucleosides

Linda Antusch, Nadine Gaß, Hans‐Achim Wagenknecht

Angewandte Chemie International Edition > 56 > 5 > 1385 - 1389

C‐nucleosides of 4‐methylbenzophenone, 4‐methoxybenzophenone, and 2′‐methoxyacetophenone were synthetically incorporated as internal photosensitizers into DNA double strands. This structurally new approach makes it possible to study the distance dependence of thymidine dimer formation because the site of photoinduced triplet energy transfer injection is clearly defined. The counterstrands to these...

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INFONA - science communication portal

Search results for: Hans-Achim Wagenknecht

The Concept of Photozymes: Short Peptides with Photoredox Catalytic Activity for Nucleophilic Additions to α‐Phenyl Styrenes

Fast and Efficient Postsynthetic DNA Labeling in Cells by Means of Strain‐Promoted Sydnone‐Alkyne Cycloadditions

Cover Feature: Fast and Efficient Postsynthetic DNA Labeling in Cells by Means of Strain‐Promoted Sydnone‐Alkyne Cycloadditions (Chem. Eur. J. 65/2021)

Cover Feature: Photoredox Catalytic Pentafluorosulfanylative Domino Cyclization of α‐Substituted Alkenes to Oxaheterocycles by Using SF₆ (Chem. Eur. J. 31/2021)

Photoredox Catalytic Pentafluorosulfanylative Domino Cyclization of α‐Substituted Alkenes to Oxaheterocycles by Using SF₆

Nucleophilic Alkoxylations of Unactivated Alkyl Olefins and α‐Methyl Styrene by Photoredox Catalysis

Front Cover: Nucleophilic Alkoxylations of Unactivated Alkyl Olefins and α‐Methyl Styrene by Photoredox Catalysis (Eur. J. Org. Chem. 5/2021)

Wie weit wandert Energie in der DNA und verursacht Schäden? Nachweis des langreichweitigen Photoschadens in DNA

Frontispiz: Wie weit wandert Energie in der DNA und verursacht Schäden? Nachweis des langreichweitigen Photoschadens in DNA

How Far Does Energy Migrate in DNA and Cause Damage? Evidence for Long‐Range Photodamage to DNA

Frontispiece: How Far Does Energy Migrate in DNA and Cause Damage? Evidence for Long‐Range Photodamage to DNA

Photoredox Catalytic α‐Alkoxypentafluorosulfanylation of α‐Methyl‐ and α‐Phenylstyrene Using SF₆

Photoredoxkatalytische α‐Alkoxypentafluorosulfanylierung von α‐Methyl‐ und α‐Phenylstyrol mithilfe von SF₆

Substitution of Metallocenes with [2.2]Paracyclophane to Enable Confocal Microscopy Imaging in Living Cells

Programmable and Sequence‐Selective Supramolecular Assembly of Two Different Chromophores along DNA Templates

Proline‐Rich Short Peptides with Photocatalytic Activity for the Nucleophilic Addition of Methanol to Phenylethylenes

Light-induced functions in DNA

Synthesis of N,N‐dimethylaminopyrene‐modified short peptides for chemical photocatalysis

Molecular movement in the Arabidopsis thaliana female gametophyte

Elucidation of the Dexter‐Type Energy Transfer in DNA by Thymine–Thymine Dimer Formation Using Photosensitizers as Artificial Nucleosides

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