Macrocyclization of Dienes under Confinement with Cationic Tungsten Imido/Oxo Alkylidene N‐Heterocyclic Carbene Complexes

F. Ziegler, J.R. Bruckner, M. Nowakowski, M. Bauer, P. Probst, B. Atwi, M.R. Buchmeiser, ChemCatChem 15 (2023).

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Journal Article | Published | English
Author
Ziegler, Felix; Bruckner, Johanna R.; Nowakowski, MichałLibreCat ; Bauer, MatthiasLibreCat ; Probst, Patrick; Atwi, Boshra; Buchmeiser, Michael R.
Abstract
Macrocyclization reactions are still challenging due to competing oligomerization, which requires the use of small substrate concentrations. Here, the cationic tungsten imido and tungsten oxo alkylidene N-heterocyclic carbene complexes [[W(N-2,6-Cl2-C6H3)(CHCMe2Ph(OC6F5)(pivalonitrile)(IMes)+ B(ArF)4−] (W1) and [W(O)(CHCMe2Ph(OCMe(CF3)2)(IMes)(CH3CN)+ B(ArF)4−] (W2) (IMes=1,3-dimesitylimidazol-2-ylidene; B(ArF)4−=tetrakis(3,5-bis(trifluoromethyl)phenyl borate) have been immobilized inside the pores of ordered mesoporous silica (OMS) with pore diameters of 3.3 and 6.8 nm, respectively, using a pore-selective immobilization protocol. X-ray absorption spectroscopy of W1@OMS showed that even though the catalyst structure is contracted due to confinement by the mesopores, both the oxidation state and structure of the catalyst stayed intact upon immobilization. Catalytic testing with four differently sized α,ω-dienes revealed a dramatically increased macrocyclization (MC) and Z-selectivity of the supported catalysts compared to the homogenous progenitors, allowing high substrate concentrations of 25 mM. With the supported complexes, a maximum increase in MC-selectivity from 27 to 81 % and in Z-selectivity from 17 to 34 % was achieved. In general, smaller mesopores exhibited a stronger confinement effect. A comparison of the two supported tungsten-based catalysts showed that W1@OMS possesses a higher MC-selectivity, while W2@OMS exhibits a higher Z-selectivity which can be rationalized by the structures of the catalysts.
Publishing Year
Journal Title
ChemCatChem
Volume
15
Issue
21
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Ziegler F, Bruckner JR, Nowakowski M, et al. Macrocyclization of Dienes under Confinement with Cationic Tungsten Imido/Oxo Alkylidene N‐Heterocyclic Carbene Complexes. ChemCatChem. 2023;15(21). doi:10.1002/cctc.202300871
Ziegler, F., Bruckner, J. R., Nowakowski, M., Bauer, M., Probst, P., Atwi, B., & Buchmeiser, M. R. (2023). Macrocyclization of Dienes under Confinement with Cationic Tungsten Imido/Oxo Alkylidene N‐Heterocyclic Carbene Complexes. ChemCatChem, 15(21). https://doi.org/10.1002/cctc.202300871
@article{Ziegler_Bruckner_Nowakowski_Bauer_Probst_Atwi_Buchmeiser_2023, title={Macrocyclization of Dienes under Confinement with Cationic Tungsten Imido/Oxo Alkylidene N‐Heterocyclic Carbene Complexes}, volume={15}, DOI={10.1002/cctc.202300871}, number={21}, journal={ChemCatChem}, publisher={Wiley}, author={Ziegler, Felix and Bruckner, Johanna R. and Nowakowski, Michał and Bauer, Matthias and Probst, Patrick and Atwi, Boshra and Buchmeiser, Michael R.}, year={2023} }
Ziegler, Felix, Johanna R. Bruckner, Michał Nowakowski, Matthias Bauer, Patrick Probst, Boshra Atwi, and Michael R. Buchmeiser. “Macrocyclization of Dienes under Confinement with Cationic Tungsten Imido/Oxo Alkylidene N‐Heterocyclic Carbene Complexes.” ChemCatChem 15, no. 21 (2023). https://doi.org/10.1002/cctc.202300871.
F. Ziegler et al., “Macrocyclization of Dienes under Confinement with Cationic Tungsten Imido/Oxo Alkylidene N‐Heterocyclic Carbene Complexes,” ChemCatChem, vol. 15, no. 21, 2023, doi: 10.1002/cctc.202300871.
Ziegler, Felix, et al. “Macrocyclization of Dienes under Confinement with Cationic Tungsten Imido/Oxo Alkylidene N‐Heterocyclic Carbene Complexes.” ChemCatChem, vol. 15, no. 21, Wiley, 2023, doi:10.1002/cctc.202300871.

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