Pavlovska, Tetiana and Lesny, David Kral and Svobodova, Eva and Hoskovcova, Irena and Archipowa, Nataliya and Kutta, Roger Jan and Cibulka, Radek (2022) Tuning Deazaflavins Towards Highly Potent Reducing Photocatalysts Guided by Mechanistic Understanding - Enhancement of the Key Step by the Internal Heavy Atom Effect. CHEMISTRY-A EUROPEAN JOURNAL, 28 (46): e202200768. ISSN 0947-6539, 1521-3765
Full text not available from this repository. (Request a copy)Abstract
Deazaflavins are well suited for reductive chemistry acting via a consecutive photo-induced electron transfer, in which their triplet state and semiquinone - the latter is formed from the former after electron transfer from a sacrificial electron donor - are key intermediates. Guided by mechanistic investigations aiming to increase intersystem crossing by the internal heavy atom effect and optimising the concentration conditions to avoid unproductive excited singlet reactions, we synthesised 5-aryldeazaflavins with Br or Cl substituents on different structural positions via a three-component reaction. Bromination of the deazaisoalloxazine core leads to almost 100 % triplet yield but causes photo-instability and enhances unproductive side reactions. Bromine on the 5-phenyl group in ortho position does not affect the photostability, increases the triplet yield, and allows its efficient usage in the photocatalytic dehalogenation of bromo- and chloroarenes with electron-donating methoxy and alkyl groups even under aerobic conditions. Reductive powers comparable to lithium are achieved.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | C-H ARYLATION; VISIBLE-LIGHT; METAL-FREE; PHOTOREDOX CATALYSIS; REDUCTIVE DEHALOGENATION; 5-DEAZAFLAVIN; ACTIVATION; RADICALS; FLAVIN; electron transfer; heavy atom effect; photocatalysis; reduction chemistry; spin-correlation |
| Subjects: | 500 Science > 540 Chemistry & allied sciences |
| Divisions: | Chemistry and Pharmacy > Institut für Physikalische und Theoretische Chemie |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 08 Feb 2024 06:29 |
| Last Modified: | 08 Feb 2024 06:29 |
| URI: | https://pred.uni-regensburg.de/id/eprint/57337 |
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