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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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| Dokumentenart | Artikel | ||||
| Titel eines Journals oder einer Zeitschrift | Chemistry – A European Journal | ||||
| Verlag: | Wiley | ||||
|---|---|---|---|---|---|
| Ort der Veröffentlichung: | WEINHEIM | ||||
| Seitenbereich: | e202202487 | ||||
| Datum | 30 August 2022 | ||||
| Institutionen | Chemie und Pharmazie > Institut für Organische Chemie > Lehrstuhl Prof. Dr. Burkhard König | ||||
| Identifikationsnummer |
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| Stichwörter / Keywords | SYNTHETIC APPLICATIONS; AEROBIC OXIDATIONS; ALCOHOLS; PHOTOCATALYSIS; SULFIDES; MECHANISM; chemoselectivity; flavin; oxidation; photocatalysis; solvated electron | ||||
| Dewey-Dezimal-Klassifikation | 500 Naturwissenschaften und Mathematik > 540 Chemie | ||||
| Status | Veröffentlicht | ||||
| Begutachtet | Ja, diese Version wurde begutachtet | ||||
| An der Universität Regensburg entstanden | Zum Teil | ||||
| URN der UB Regensburg | urn:nbn:de:bvb:355-epub-530558 | ||||
| Dokumenten-ID | 53055 |
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