Stockerl, Willibald J. and Gschwind, Ruth M. (2023) Photo enhancement reveals (E,Z) and (Z,Z) configurations as additional intermediates in iminium ion catalysis. CHEMICAL COMMUNICATIONS, 59 (10). pp. 1325-1328. ISSN 1359-7345, 1364-548X
Full text not available from this repository. (Request a copy)Abstract
Imidazolidinone-based alpha,beta-unsaturated iminium ions are the reactive species within countless synthetic protocols in asymmetric organocatalysis. However, (E,Z) and (Z,Z) imidazolidinone iminium ions, i.e. (Z)-C=C configurations, have been elusive so far. Herein we describe how in situ photoisomerization enables the observation and assignment of high energetic (Z)-configured intermediates below the detection limit of NMR spectroscopy for (E,Z) and (Z,Z) iminium perchlorate complexes derived from MacMillan's 1st generation catalyst and cinnamaldehyde. Traces of (E,Z) could even be detected under synthetic conditions at 25 ? in MeCN. Using back isomerization studies and diffusion ordered spectroscopy, conditions were found to stabilize the (E,Z) and (Z,Z) isomers for several hours via ion pair aggregation. Thus, at least (E,Z) should be considered for future investigations in asymmetric iminium ion catalysis.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | PROTON CHEMICAL-EXCHANGE; ORGANIC CATALYSIS; TRANSFER HYDROGENATION; SATURATION-TRANSFER; MECHANISTIC TOOL; STRATEGIES; PHOTOISOMERIZATION; STABILIZATION; ISOMERIZATION; WATER |
| Subjects: | 500 Science > 540 Chemistry & allied sciences |
| Divisions: | Chemistry and Pharmacy > Institut für Organische Chemie > Arbeitskreis Prof. Dr. Ruth Gschwind |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 20 Feb 2024 10:06 |
| Last Modified: | 20 Feb 2024 10:06 |
| URI: | https://pred.uni-regensburg.de/id/eprint/56689 |
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