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Sulfone "Geländer" Helices: Revealing Unexpected Parameters Controlling the Enantiomerization Process
JournalArticle (Originalarbeit in einer wissenschaftlichen Zeitschrift)
 
ID 4634304
Author(s) Mannancherry, Rajesh; Solomek, Tomas; Cavalli, Diana; Malincik, Juraj; Häussinger, Daniel; Prescimone, Alessandro; Mayor, Marcel
Author(s) at UniBasel Mayor, Marcel
Mannancherry, Rajesh
Solomek, Tomas
Cavalli, Diana
Malincik, Juraj
Prescimone, Alessandro
Häussinger, Daniel
Year 2021
Title Sulfone "Geländer" Helices: Revealing Unexpected Parameters Controlling the Enantiomerization Process
Journal Journal of Organic Chemistry
Volume 86
Number 8
Pages / Article-Number 5431-5442
Mesh terms Circular Dichroism; Magnetic Resonance Spectroscopy; Stereoisomerism; Sulfones; X-Ray Diffraction
Abstract The two sulfonyl-bridged Geländer helices 1a and 2a are obtained by oxidation of the corresponding sulfide bridged precursors 1b and 2b. Both Geländer structures are fully characterized by NMR, high-resolution mass spectrometry, and optical spectroscopies. X-ray diffraction with a single crystal of 2a provides its solid-state structure. Both Geländer helices 1a and 2a are separated into enantiomers, and their racemizations are monitored by circular dichroism. For 1a, consisting of two equally sized macrocycles, a substantial increase in the enantiomerization barrier is observed upon going from the sulfide to the sulfone, and only a subtle rise is detected for the constitutional isomer 2a with two macrocycles of different size during the same transformation. This results not only in 1a with the highest configurational stability in the series of hitherto investigated Geländer structures but also challenges the so far hypothesized correlations between bridging structures and the Gibbs free energy of enantiomerization. The simulation of the enantiomerization process in the macrocyclic subunits suggests the proximity of the endotopic hydrogens as parameter responsible for the heights of the enantiomerization barrier.
Publisher American Chemical Society
ISSN/ISBN 0022-3263 ; 1520-6904
URL https://doi.org/10.1021/acs.joc.0c03016
edoc-URL https://edoc.unibas.ch/85432/
Full Text on edoc No
Digital Object Identifier DOI 10.1021/acs.joc.0c03016
PubMed ID http://www.ncbi.nlm.nih.gov/pubmed/33650868
ISI-Number 000641292800001
Document type (ISI) Journal Article
 
   

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28/03/2024