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Obertik, Robert ; Chudoba, Josef ; Šturala, Jiri ; Tarábek, Ján ; Ludvíková, Lucie ; Slanina, Tomas ; König, Burkhard ; Cibulka, Radek

Highly Chemoselective Catalytic Photooxidations by Using Solvent as a Sacrificial Electron Acceptor

Obertik, Robert, Chudoba, Josef, Šturala, Jiri , Tarábek, Ján , Ludvíková, Lucie , Slanina, Tomas , König, Burkhard und Cibulka, Radek (2022) Highly Chemoselective Catalytic Photooxidations by Using Solvent as a Sacrificial Electron Acceptor. Chemistry – A European Journal, e202202487.

Veröffentlichungsdatum dieses Volltextes: 17 Okt 2022 08:42
Artikel
DOI zum Zitieren dieses Dokuments: 10.5283/epub.53055


Zusammenfassung

Catalyst recovery is an integral part of photoredox catalysis. It is often solved by adding another component-a sacrificial agent-whose role is to convert the catalyst back into its original oxidation state. However, an additive may cause a side reaction thus decreasing the selectivity and overall efficiency. Herein, we present a novel approach towards chemoselective photooxidation reactions ...

Catalyst recovery is an integral part of photoredox catalysis. It is often solved by adding another component-a sacrificial agent-whose role is to convert the catalyst back into its original oxidation state. However, an additive may cause a side reaction thus decreasing the selectivity and overall efficiency. Herein, we present a novel approach towards chemoselective photooxidation reactions based on suitable solvent-acetonitrile acting simultaneously as an electron acceptor for catalyst recovery, and on anaerobic conditions. This is allowed by the unique properties of the catalyst, 7,8-dimethoxy-3-methyl-5-phenyl-5-deazaflavinium chloride existing in both strongly oxidizing and reducing forms, whose strength is increased by excitation with visible light. Usefulness of this system is demonstrated in chemoselective dehydrogenations of 4-methoxy- and 4-chlorobenzyl alcohols to aldehydes without over-oxidation to benzoic acids achieving yields up to 70 %. 4-Substituted 1-phenylethanols were oxidized to ketones with yields 80-100 % and, moreover, with yields 31-98 % in the presence of benzylic methyl group, diphenylmethane or thioanisole which are readily oxidized in the presence of oxygen but these were untouched with our system. Mechanistic studies based on UV-Vis spectro-electrochemistry, EPR and time-resolved spectroscopy measurements showed that the process involving an electron release from an excited deazaflavin radical to acetonitrile under formation of solvated electron is crucial for the catalyst recovery.



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Details

DokumentenartArtikel
Titel eines Journals oder einer ZeitschriftChemistry – A European Journal
Verlag:Wiley
Ort der Veröffentlichung:WEINHEIM
Seitenbereich:e202202487
Datum30 August 2022
InstitutionenChemie und Pharmazie > Institut für Organische Chemie > Lehrstuhl Prof. Dr. Burkhard König
Identifikationsnummer
WertTyp
10.1002/chem.202202487DOI
Stichwörter / KeywordsSYNTHETIC APPLICATIONS; AEROBIC OXIDATIONS; ALCOHOLS; PHOTOCATALYSIS; SULFIDES; MECHANISM; chemoselectivity; flavin; oxidation; photocatalysis; solvated electron
Dewey-Dezimal-Klassifikation500 Naturwissenschaften und Mathematik > 540 Chemie
StatusVeröffentlicht
BegutachtetJa, diese Version wurde begutachtet
An der Universität Regensburg entstandenZum Teil
URN der UB Regensburgurn:nbn:de:bvb:355-epub-530558
Dokumenten-ID53055

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