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Highly Active Cationic NHC, Phosphine Iridium Catalysts for Base Free Asymmetric Hydrogenation of Ketones
Stockholm University, Faculty of Science, Department of Organic Chemistry.ORCID iD: 0000-0002-6053-8828
Stockholm University, Faculty of Science, Department of Organic Chemistry.
Stockholm University, Faculty of Science, Department of Organic Chemistry.
Stockholm University, Faculty of Science, Department of Organic Chemistry.
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(English)Manuscript (preprint) (Other academic)
National Category
Organic Chemistry
Research subject
Organic Chemistry
Identifiers
URN: urn:nbn:se:su:diva-119682OAI: oai:DiVA.org:su-119682DiVA, id: diva2:847685
Available from: 2015-08-21 Created: 2015-08-21 Last updated: 2018-02-06Bibliographically approved
In thesis
1. Hydrogenation, Transfer Hydrogenation and Hydrogen Transfer Reactions Catalyzed by Iridium Complexes
Open this publication in new window or tab >>Hydrogenation, Transfer Hydrogenation and Hydrogen Transfer Reactions Catalyzed by Iridium Complexes
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The work described in this thesis is focused on the development of new bidentate iridium complexes and their applications in the asymmetric reduction of olefins, ketones and imines. Three new types of iridium complexes were synthesized, which included pyridine derived chiral N,P-iridium complexes, achiral NHC complexes and chiral NHC-phosphine complexes. A study of their catalytic applications demonstrated a high efficiency of the N,P-iridium complexes for asymmetric hydrogenation of olefins, with good enantioselectivity. The carbene complexes were found to be very efficient hydrogen transfer mediators capable of abstracting hydrogen from alcohols and subsequently transfer it to other unsaturated bonds. This hydrogen transferring property of the carbene complexes was used in the development of C–C and C–N bond formation reactions via the hydrogen borrowing process. The complexes displayed high catalytic reactivity using 0.5–1.0 mol% of the catalyst and mild reaction conditions. Finally chiral carbene complexes were found to be activated by hydrogen gas. Their corresponding iridium hydride species were able to reduce ketones and imines with high efficiency and enantioselectivity without any additives, base or acid.

Place, publisher, year, edition, pages
Stockholm: Department of Organic Chemistry, Stockholm University, 2015. p. 69
Keywords
Iridium catalyst, carbene, N, P - ligand, asymmetric hydrogenation, transfer hydrogenation, hydrogen transfer reaction, alkylation, olefin, ketone, amide
National Category
Organic Chemistry
Research subject
Organic Chemistry
Identifiers
urn:nbn:se:su:diva-119701 (URN)978-91-7649-255-0 (ISBN)
Public defence
2015-09-30, Magnélisalen, Kemiska övningslaboratoriet, Svante Arrhenius väg 16 B, Stockholm, 10:15 (English)
Opponent
Supervisors
Note

At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 5: Submitted. Paper 6: Manuscript.

 

Available from: 2015-09-08 Created: 2015-08-21 Last updated: 2015-09-08Bibliographically approved
2. NHC,P- and N,P-Iridium Catalysts for Hydrogenations and Hydrogen Transfer Reactions
Open this publication in new window or tab >>NHC,P- and N,P-Iridium Catalysts for Hydrogenations and Hydrogen Transfer Reactions
2018 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The work described in this thesis is focused on hydrogenation and hydrogen transfer reactions using iridium catalysts. The first part concerns the use of N-heterocyclic carbene-phosphine iridium complexes in alkylation reactions (Chapters 2 and 3) and the hydrogenation of ketones (Chapter 4). A number of N-heterocyclic carbene-phosphine iridium complexes have been prepared and evaluated as catalysts for C-N bond formation of amides using alcohols as the electrophile. This catalytic system can be used with a wide range of substrates at low catalyst loading (only 0.5 mol%) to furnish the desired products in up to 98% isolated yield. The achiral N-heterocyclic carbene-phosphine iridium complexes were also found to catalyze the methylation of ketones with methanol under mild conditions to afford the mono-methylated products in up to 98% isolated yield with low catalyst loading (1.0 mol%). Additionally, several chiral N-heterocyclic carbene-phosphine iridium complexes were synthesized and evaluated in asymmetric hydrogenation of ketones. The reactions were carried out at room temperature under base-free conditions to obtain the chiral alcohols in up to 96% ee in 30 minutes.

The second part of this thesis (Chapter 5) details the preparation of new N,P-iridium complexes which were found to be highly efficient catalysts for the asymmetric hydrogenation of challenging tetrasubstituted olefins. This catalytic system results in optically active compounds of high enantiomeric excess (up to 98% ee) as the single diasteroisomer.

Place, publisher, year, edition, pages
Stockholm: Department of Organic Chemistry, Stockholm University, 2018
Keywords
Iridium catalyst, carbene, N, P-ligand, asymmetric hydrogenation, alkylation, hydrogen transfer reaction
National Category
Organic Chemistry
Research subject
Organic Chemistry
Identifiers
urn:nbn:se:su:diva-152341 (URN)978-91-7797-120-7 (ISBN)978-91-7797-121-4 (ISBN)
Public defence
2018-03-16, Magnélisalen, Kemiska övningslaboratoriet, Svante Arrhenius väg 16 B, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Manuscript. Paper 4: Manuscript.

Available from: 2018-02-21 Created: 2018-01-31 Last updated: 2018-04-16Bibliographically approved

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