Hartman, Tomas and Reisnerova, Martina and Chudoba, Josef and Svobodova, Eva and Archipowa, Nataliya and Kutta, Roger Jan and Cibulka, Radek (2021) Photocatalytic Oxidative [2+2] Cycloelimination Reactions with Flavinium Salts: Mechanistic Study and Influence of the Catalyst Structure. CHEMPLUSCHEM, 86 (3). pp. 373-386. ISSN 2192-6506
Full text not available from this repository. (Request a copy)Abstract
Flavinium salts are frequently used in organocatalysis but their application in photoredox catalysis has not been systematically investigated to date. We synthesized a series of 5-ethyl-1,3-dimethylalloxazinium salts with different substituents in the positions 7 and 8 and investigated their application in light-dependent oxidative cycloelimination of cyclobutanes. Detailed mechanistic investigations with a coumarin dimer as a model substrate reveal that the reaction preferentially occurs via the triplet-born radical pair after electron transfer from the substrate to the triplet state of an alloxazinium salt. The very photostable 7,8-dimethoxy derivative is a superior catalyst with a sufficiently high oxidation power (E*=2.26 V) allowing the conversion of various cyclobutanes (with E-ox up to 2.05 V) in high yields. Even compounds such as all-trans dimethyl 3,4-bis(4-methoxyphenyl)cyclobutane-1,2-dicarboxylate can be converted, whose opening requires a high activation energy due to a missing pre-activation caused by bulky adjacent substituents in cis-position.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | DIMETHYLTHYMINE CYCLOBUTANE DIMER; REDOX-PHOTOSENSITIZED REACTIONS; VISIBLE-LIGHT; ELECTRON-TRANSFER; RING-CLEAVAGE; DIARYLCYCLOBUTANES; REACTIVITY; CYCLOREVERSION; MONOMERIZATION; PHOTOLYASE; cyclobutanes; cycloelimination reactions; electron transfer; photocatalysis; time-resolved spectroscopy |
| Subjects: | 500 Science > 540 Chemistry & allied sciences |
| Divisions: | Chemistry and Pharmacy > Institut für Physikalische und Theoretische Chemie > Chair of Physical Chemistry I |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 26 Aug 2022 05:38 |
| Last Modified: | 26 Aug 2022 05:38 |
| URI: | https://pred.uni-regensburg.de/id/eprint/47004 |
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