Universität zu Köln

Holland, Mareike C., Berden, Giel, Oomens, Jos, Meijer, Anthony J. H. M., Schaefer, Mathias ORCID: 0000-0002-5943-4335 and Gilmour, Ryan (2014). Infrared Multiphoton Dissociation Spectroscopic Analysis of Noncovalent Interactions in Organocatalysis. Eur. J. Org. Chem., 2014 (26). S. 5675 - 5681. WEINHEIM: WILEY-V C H VERLAG GMBH. ISSN 1099-0690

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Abstract

Herein we report the first application of infrared multiplephoton dissociation (IRMPD) spectroscopy to study noncovalent interactions in organocatalysis. Phenylalanine-derived iminium ions, central to numerous organocatalytic processes, display dynamic conformational behavior as a consequence of stabilizing noncovalent interactions (e. g., CH-pi, pi-pi). Electronic modulation of the aryl ring causes notable variation in the conformation; this can be detected spectroscopically and correlated with enantioselectivity. Given that these interactions, which orchestrate stereoinduction, encode for specific conformers (I, II, or III), a diagnostic IRMPD spectrum is generated: the C=O stretching frequency of the imidazole carbonyl group serves as a diagnostic marker. The calculated conformers and their respective spectra can be compared with experimental data. Consequently, valuable insight into the ubiquitous noncovalent interactions associated with Mac-Millan-catalyst-derived alpha,beta-unsaturated iminium ions can be obtained in the absence of solvent or counterion effects. A preliminary structure-catalysis correlation is disclosed, thus demonstrating the potential of this approach for studying reactive intermediates and facilitating catalyst design.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Holland, Mareike C. UNSPECIFIED UNSPECIFIED UNSPECIFIED Berden, Giel UNSPECIFIED UNSPECIFIED UNSPECIFIED Oomens, Jos UNSPECIFIED UNSPECIFIED UNSPECIFIED Meijer, Anthony J. H. M. UNSPECIFIED UNSPECIFIED UNSPECIFIED Schaefer, Mathias UNSPECIFIED orcid.org/0000-0002-5943-4335 UNSPECIFIED Gilmour, Ryan UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-430119
DOI:	10.1002/ejoc.201402845
Journal or Publication Title:	Eur. J. Org. Chem.
Volume:	2014
Number:	26
Page Range:	S. 5675 - 5681
Date:	2014
Publisher:	WILEY-V C H VERLAG GMBH
Place of Publication:	WEINHEIM
ISSN:	1099-0690
Language:	English
Faculty:	Faculty of Mathematics and Natural Sciences
Divisions:	Faculty of Mathematics and Natural Sciences > Department of Chemistry > Institute of Organic Chemistry
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language CATION-PI INTERACTIONS; GAS-PHASE; DISPERSION INTERACTIONS; IRMPD-SPECTROSCOPY; X-RAY; CATALYSIS; ION; DERIVATIVES; REACTIVITY; COMPLEXES Multiple languages Chemistry, Organic Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/43011