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Hecht, Markus ; Dullinger, Philipp ; Silva, Wagner ; Horinek, Dominik ; Gschwind, Ruth M.

Highly Acidic N-Triflylphosphoramides as Chiral Brønsted Acid Catalysts: The Effect of Weak Hydrogen Bonds and Multiple Acceptors on Complex Structures and Aggregation

Article

Hecht, Markus , Dullinger, Philipp, Silva, Wagner , Horinek, Dominik and Gschwind, Ruth M. (2024) Highly Acidic N-Triflylphosphoramides as Chiral Brønsted Acid Catalysts: The Effect of Weak Hydrogen Bonds and Multiple Acceptors on Complex Structures and Aggregation. Chemical Science 15, pp. 9104-9111. (In Press)

DOI to cite this document: 10.5283/epub.58272


Abstract

N-Triflylphosphoramides (NTPAs) represent an important catalyst class in asymmetric catalysis due to their multiple hydrogen bond acceptor sites and acidity, which is increased by several orders of magnitude compared to conventional chiral phosphoric acids (CPAs). Thus, NTPAs allow for several challenging transformations, which are not accessible with CPAs. However, detailed evidence on their ...

N-Triflylphosphoramides (NTPAs) represent an important catalyst class in asymmetric catalysis due to their multiple hydrogen bond acceptor sites and acidity, which is increased by several orders of magnitude compared to conventional chiral phosphoric acids (CPAs). Thus, NTPAs allow for several challenging transformations, which are not accessible with CPAs. However, detailed evidence on their hydrogen bonding situation, complex structures and aggregation is still lacking. Therefore, this study covers the hydrogen bonding behavior and structural features of binary NTPA/imine complexes compared to their CPA counterparts. Deviating from the single-well potential hydrogen bonds commonly observed in CPA/imine complexes, the NTPA/imine complexes exhibit a tautomeric equilibrium between two proton positions. Low-temperature NMR at 180 K supported by computer simulations indicate a OHN hydrogen bond between the phosphoramide oxygen and the imine, instead of the mostly proposed NHN H-bond. Furthermore, this study finds no evidence for the existence of dimeric NTPA/NTPA/imine complexes as previously suggested for CPA systems, both synthetically and through NMR studies.



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Details

Item typeArticle
Journal or Publication TitleChemical Science
PublisherRoyal Society of Chemistry
Open Access TypeCC-License
Volume15
Page Rangepp. 9104-9111
Date2024
Date of publication16 May 2024 06:50
InstitutionsChemistry and Pharmacy > Institut für Organische Chemie > Arbeitskreis Prof. Dr. Ruth Gschwind
Chemistry and Pharmacy > Institut für Physikalische und Theoretische Chemie > Chair of Chemistry VI - Physical Chemistry (Solution Chemistry) > Prof. Dr. Dominik Horinek
Identification Number
ValueType
10.1039/D4SC01939CDOI
Dewey Decimal Classification500 Science > 540 Chemistry & allied sciences
StatusIn Press
RefereedYes, this version has been refereed
Created at the University of RegensburgYes
URN of the UB Regensburgurn:nbn:de:bvb:355-epub-582720
Item ID58272

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