Dynamic Stereochemistry of a Biphenyl-Bisprolineamide Model Catalyst and its Imidazolidinone Intermediates.

Autor: Golub TP; Ruhr Universität Bochum, Fakultät für Chemie und Biochemie, Organische Chemie II, Universitätsstraße 150, 44801, Bochum, Germany., Feßner M; Ruhr Universität Bochum, Fakultät für Chemie und Biochemie, Organische Chemie II, Universitätsstraße 150, 44801, Bochum, Germany., Engelage E; Ruhr Universität Bochum, Fakultät für Chemie und Biochemie, Organische Chemie II, Universitätsstraße 150, 44801, Bochum, Germany., Merten C; Ruhr Universität Bochum, Fakultät für Chemie und Biochemie, Organische Chemie II, Universitätsstraße 150, 44801, Bochum, Germany.
Jazyk: angličtina
Zdroj: Chemistry (Weinheim an der Bergstrasse, Germany) [Chemistry] 2022 Aug 10; Vol. 28 (45), pp. e202201317. Date of Electronic Publication: 2022 Jun 23.
DOI: 10.1002/chem.202201317
Abstrakt: In this study, we characterize the dynamic stereochemistry of a biphenyl-2,2'-bis(proline amide) catalyst in chloroform and DMSO as representative weakly and strongly hydrogen bonding solvents. Using vibrational circular dichroism (VCD) spectroscopy and density functional theory (DFT) based spectra calculations, we show that the preferred axial stereochemistry of the catalyst is determined by solute-solvent interactions. Explicitly considering solvation with DMSO molecules is found to be essential to correctly predict the conformational preferences of the catalyst. Furthermore, we investigate the stereochemistry of the corresponding enamines and imidazolidinones that are formed upon reaction with isovaleraldehyde. The enamines are found to rapidly convert to endo-imidazolidinones and the thermodynamically favored exo-imidazolidinones are formed only slowly. The present study demonstrates that the stereochemistry of these imidazolidinones can be deduced directly from the VCD spectra analysis without any further detailed analysis of NMR spectra. Hence, we herein exemplify the use of VCD spectroscopy for an in situ characterization of intermediates relevant in asymmetric catalysts.
(© 2022 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)
Databáze: MEDLINE
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