Ghosh, T. and Slanina, T. and Koenig, B. (2015) Visible light photocatalytic reduction of aldehydes by Rh(III)-H: a detailed mechanistic study. CHEMICAL SCIENCE, 6 (3). pp. 2027-2034. ISSN 2041-6520, 2041-6539
Full text not available from this repository. (Request a copy)Abstract
The chemoselective photoreduction of aldehydes in the presence of ketones was achieved using triethanolamine (TEOA) as sacrificial electron donor, proflavine (PF) as photocatalyst and [Cp*Rh(III)(bpy) Cl]Cl (Rh-cat) as mediator. The reducing agent, which reacts with the carbonyl group was found to be [Cp*Rh(III)(bpy)H]Cl (Rh(III)-H). Contrary to formate-based reduction, its slow photochemical in situ generation enables to kinetically distinguish aldehydes from ketones. The inherent reactivity difference of the carbonyl compounds is transferred by the method into synthetically useful reaction selectivities. The substrate scope is broad with excellent yields. A detailed study of the reaction mechanism reveals that the photoreduction of the PF triplet and the subsequent reduction of the Rh-cat leading to Rh(III)-H represents the major reaction pathway, which is highly oxygen sensitive. The oxidative quenching of the PF singlet state by Rh-cat is a competing mechanism, which prevails in non-degassed systems.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | SODIUM-BOROHYDRIDE; CHEMOSELECTIVE REDUCTION; BIOORGANOMETALLIC CHEMISTRY; REGIOSELECTIVE REDUCTION; 1,4-NADH DERIVATIVES; HYDROGEN EVOLUTION; NADH REGENERATION; ACIDIC MEDIA; KETONES; PROFLAVIN; |
| Subjects: | 500 Science > 540 Chemistry & allied sciences |
| Divisions: | Chemistry and Pharmacy > Institut für Organische Chemie > Lehrstuhl Prof. Dr. Burkhard König |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 01 Aug 2019 12:12 |
| Last Modified: | 01 Aug 2019 12:12 |
| URI: | https://pred.uni-regensburg.de/id/eprint/6298 |
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