Chiral Pyrazolinylidene Complexes for Asymmetric Catalysis
- 1Fachbereich Chemie Philipps‐Universität Marburg Marburg Germany
Abstract
The strong σ‐donating properties of N‐heterocyclic carbenes (NHCs) have established them as key ligands in homogeneous catalysis. However, among this class of ligands, pyrazolinylidenes remain largely unexplored. Herein, we introduce the development of the first chiral pyrazolinylidene transition metal complex for asymmetric catalysis. Specifically, a chiral‐at‐ruthenium catalyst incorporating bidentate N‐(2‐pyridyl)‐substituted pyrazolin‐5‐ylidene ligands within a C 2‐symmetric octahedral framework is reported. The modular ligand synthesis enables systematic variation at both the pyridine and carbene backbones, providing access to a series of air‐stable ruthenium(II) complexes. Spectroscopic analysis indicates enhanced σ‐donor strength compared to related imidazolin‐2‐ylidene and mesoionic carbene congeners, contributing to increased electron density at the metal center and a pronounced transeffect. The resulting complexes were evaluated in the enantioselective intramolecular aziridination of an alkene‐tethered N‐benzoyloxyurea, affording a bicyclic urea‐based aziridine containing a quaternary stereocenter in up to 95% yield and 98% enantiomeric excess. These findings reveal pyrazolin‐5‐ylidenes as powerful ligands for chiral transition metal catalysis and establish a robust catalyst scaffold to be applied to other asymmetric transformations.
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BibTeX
@article{moller2026chiral,
title = {{Chiral Pyrazolinylidene Complexes for Asymmetric Catalysis}},
author = {Felix Möller and Nemrud Demirel and Thomas Krüger and Linus Plohnke and Jennifer Schröder and Sergei I. Ivlev and Eric Meggers},
journal = {Chemistry (Weinheim an Der Bergstrasse, Germany)},
year = {2026},
month = jul,
doi = {10.1002/chem.71426},
url = {https://doi.org/10.1002/chem.71426},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Chiral Pyrazolinylidene Complexes for Asymmetric Catalysis
AU - Felix Möller
AU - Nemrud Demirel
AU - Thomas Krüger
AU - Linus Plohnke
AU - Jennifer Schröder
AU - Sergei I. Ivlev
AU - Eric Meggers
PY - 2026
DA - 2026/07/12
JO - Chemistry (Weinheim an Der Bergstrasse, Germany)
DO - 10.1002/chem.71426
UR - https://doi.org/10.1002/chem.71426
AB - The strong σ‐donating properties of N‐heterocyclic carbenes (NHCs) have established them as key ligands in homogeneous catalysis. However, among this class of ligands, pyrazolinylidenes remain largely unexplored. Herein, we introduce the development of the first chiral pyrazolinylidene transition metal complex for asymmetric catalysis. Specifically, a chiral‐at‐ruthenium catalyst incorporating bidentate N‐(2‐pyridyl)‐substituted pyrazolin‐5‐ylidene ligands within a C 2‐symmetric octahedral framework is reported. The modular ligand synthesis enables systematic variation at both the pyridine and carbene backbones, providing access to a series of air‐stable ruthenium(II) complexes. Spectroscopic analysis indicates enhanced σ‐donor strength compared to related imidazolin‐2‐ylidene and mesoionic carbene congeners, contributing to increased electron density at the metal center and a pronounced transeffect. The resulting complexes were evaluated in the enantioselective intramolecular aziridination of an alkene‐tethered N‐benzoyloxyurea, affording a bicyclic urea‐based aziridine containing a quaternary stereocenter in up to 95% yield and 98% enantiomeric excess. These findings reveal pyrazolin‐5‐ylidenes as powerful ligands for chiral transition metal catalysis and establish a robust catalyst scaffold to be applied to other asymmetric transformations.
SN - 0947-6539
SN - 1521-3765
ER -