Svoboda, Jiri and Schmaderer, Harald and Koenig, Burkhard (2008) Thiourea-enhanced flavin photooxidation of benzyl alcohol. CHEMISTRY-A EUROPEAN JOURNAL, 14 (6). pp. 1854-1865. ISSN 0947-6539
Full text not available from this repository. (Request a copy)Abstract
Upon irradiation, flavin oxidises 4-methoxybenzyl alcohol to the corresponding aldehyde using aerial 02 as the terminal oxidant. We have observed that this reaction is significantly accelerated by the presence of thiourea. A series of thiourea-functionalised flavins has been prepared from flavin isothiocyanates and their photocatalytic efficiencies have been monitored by NMR. The alcohol photooxidation proceeds rapidly and cleanly with high turnover numbers of up to 580, exceeding previously reported performances. A likely mechanistic rationale for the more than 30-fold acceleration of the photo-redox reaction by thiourea has been derived from spectroscopic, electrochemical, and kinetic studies. Thus, thiourea acts as an electron-transfer mediator for the initial photooxidation of 4-methoxybenzyl alcohol by the excited flavins. This mechanism has similarities to electron-relay mechanisms in flavoenzymes, for which cysteine sulfenic acid intermediates are proposed. The observation that thiourea mediates flavin photo-redox processes is valuable for the design of more sophisticated photocatalysts based on Nature's best redox chromophore.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | ELECTRON-TRANSFER; MODEL SYSTEMS; FLAVOENZYME ACTIVITY; HYDROGEN-PEROXIDE; REDOX PROPERTIES; SULFENIC ACIDS; MOLECULAR RECOGNITION; CONTAINING MONOOXYGENASE; 4-METHOXYBENZYL ALCOHOL; OXIDATIVE STRESS; flavins; photooxidation; redox chemistry; thiourea |
| Subjects: | 500 Science > 540 Chemistry & allied sciences |
| Divisions: | Chemistry and Pharmacy > Institut für Organische Chemie > Lehrstuhl Prof. Dr. Burkhard König |
| Depositing User: | Petra Gürster |
| Date Deposited: | 18 Dec 2020 09:34 |
| Last Modified: | 18 Dec 2020 09:34 |
| URI: | https://pred.uni-regensburg.de/id/eprint/31579 |
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