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The Use of N,P-Iridium and N,P-Palladium Complexes in Asymmetric Synthesis
Stockholm University, Faculty of Science, Department of Organic Chemistry.
2018 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The work presented in this thesis concerns asymmetric catalysis using chiral N,P-ligands and iridium or palladium transition metals. The first part  (Chapters 2 and 3) highlights the N,P-iridium catalyzed asymmetric hydrogenation of 1,4-cyclohexadienes having functionalized or unfunctionalized substituents, including allylsilane side chains. A series of N,P-iridium catalysts were synthesized and screened on a number of cyclohexadienes. The developed N,P-iridium catalysts have provided excellent chemo-, regio- and enantioselectivity for most of the products obtained. For substrates having an allylsilane sidechain, the chiral cyclic allylsilane products were used to induce stereocontrol in a subsequent Hosomi-Sakurai reaction using TiCl4 as Lewis acid and aldehydes as electrophiles. The corresponding homoallylic alcohols were obtained in good to excellent diastereoselectivity. 

The second part (Chapter 4) describes the N,P-iridium catalyzed asymmetric hydrogenation of various vinyl fluorides. A number of tri- and tetrasubstituted vinyl fluorides were synthesized and evaluated for the asymmetric hydrogenation. The corresponding saturated chiral fluoro compounds were obtained in very high enantioselectivity (up to 99% ee). The defluorination, usually known to occur under the catalytic hydrogenation conditions, were not observed for the majority of the substrates. 

Finally, Chapter 5 describes the application of N,P-ligands in the asymmetric cycloisomerization of 1,6-enynes using a palladium precatalyst. The enantioselectivities for the products were found to depend both on the substrate as well as the hydrogen source. These developed catalytic reactions provide attractive methods to create multiple stereogenic centers in a molecule in relatively few steps from readily available starting materials.

Place, publisher, year, edition, pages
Stockholm: Department of Organic Chemistry, Stockholm University , 2018. , p. 66
Keywords [en]
Iridium, Asymmetric Hydrogenation, Palladium, Asymmetric Cycloisomerization and Hosomi-Sakurai Allylation
National Category
Organic Chemistry
Research subject
Organic Chemistry
Identifiers
URN: urn:nbn:se:su:diva-150602ISBN: 978-91-7797-061-3 (print)ISBN: 978-91-7797-062-0 (electronic)OAI: oai:DiVA.org:su-150602DiVA, id: diva2:1169503
Public defence
2018-01-31, Magnélisalen, Kemiska övningslaboratoriet, Svante Arrhenius väg 16 B, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

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

Available from: 2018-01-08 Created: 2017-12-27 Last updated: 2018-01-11Bibliographically approved
List of papers
1. Enantio- and Regioselective Ir-Catalyzed Hydrogenation of Di- and Trisubstituted Cycloalkenes
Open this publication in new window or tab >>Enantio- and Regioselective Ir-Catalyzed Hydrogenation of Di- and Trisubstituted Cycloalkenes
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2016 (English)In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 138, no 36, p. 11930-11935Article in journal (Refereed) Published
Abstract [en]

A number of cyclic olefins Were prepared and evaluated for the asymmetric hydrogenation reaction using novel N,P-ligated iridium imidazote-based Catalysts (Crabtree type). The diversity of these cyclic olefins spanned those having little functionality to others bearing strongly coordinating substituents and heterocycles. Excellent enantioselectivities were observed both for substrates having little functionality (up to >99% ee) and for substrates possessing functional groups several carbons away from the olefin. Substrates having functionalities such as carboxyl groups, alcohols, or heterocycles in the vicinity of the C=C bond were hydrogenated in high enantiomeric excess (up to >99% ee). The hydrogenation was also found to be regioselective, and by controlling the reaction conditions, selective hydrogenation of one of two trisubstituted olefins can be achieved: Furthermore, trisubstituted olefins can be selectively hydrogenated in the presence of tetrasubstituted olefins.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2016
National Category
Organic Chemistry
Research subject
Organic Chemistry
Identifiers
urn:nbn:se:su:diva-135188 (URN)10.1021/jacs.6b07291 (DOI)000383410700067 ()27548029 (PubMedID)
Funder
Swedish Energy AgencySwedish Research CouncilKnut and Alice Wallenberg FoundationStiftelsen Olle Engkvist Byggmästare
Available from: 2016-11-21 Created: 2016-11-01 Last updated: 2018-03-22Bibliographically approved
2. Ir-Catalyzed Asymmetric and Regioselective Hydrogenation of Cyclic Allylsilanes and Generation of Quaternary Stereocenters via the Hosomi-Sakurai Allylation
Open this publication in new window or tab >>Ir-Catalyzed Asymmetric and Regioselective Hydrogenation of Cyclic Allylsilanes and Generation of Quaternary Stereocenters via the Hosomi-Sakurai Allylation
2018 (English)In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 24, no 7, p. 1681-1685Article in journal (Refereed) Published
Abstract [en]

A number of cyclic dienes containing the allylsilane moiety were prepared via Birch reduction and subjected to iridium-catalyzed regioselective and asymmetric hydrogenation, which provided chiral allylsilanes in high conversion and enantiomeric excess (up to 99 % ee). The compounds were successively used in the Hosomi-Sakurai allylation with various aldehydes employing TiCl4 as Lewis acid, providing adducts with two additional stereogenic centers in excellent diastereoselectivity.

Keywords
allylation, asymmetric reactions, hydrogenation, iridium, regioselectivity
National Category
Chemical Sciences
Research subject
Organic Chemistry
Identifiers
urn:nbn:se:su:diva-150597 (URN)10.1002/chem.201704684 (DOI)000423804800026 ()
Funder
Stiftelsen Olle Engkvist Byggmästare
Available from: 2017-12-27 Created: 2017-12-27 Last updated: 2018-03-22Bibliographically approved
3. N,P-Iridium Catalyzed Asymmetric Hydrogenation of Vinyl Fluorides
Open this publication in new window or tab >>N,P-Iridium Catalyzed Asymmetric Hydrogenation of Vinyl Fluorides
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(English)Manuscript (preprint) (Other academic)
National Category
Organic Chemistry
Research subject
Organic Chemistry
Identifiers
urn:nbn:se:su:diva-150613 (URN)
Available from: 2017-12-28 Created: 2017-12-28 Last updated: 2017-12-28Bibliographically approved
4. Thiazole, Imidazole and Oxazoline Based N,P-Ligands for Palladium-Catalyzed Cycloisomerization of 1,6-Enynes
Open this publication in new window or tab >>Thiazole, Imidazole and Oxazoline Based N,P-Ligands for Palladium-Catalyzed Cycloisomerization of 1,6-Enynes
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2016 (English)In: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, no 20, p. 3427-3433Article in journal (Refereed) Published
Abstract [en]

A series of N,P-ligands were prepared and evaluated in the asymmetric palladium-catalyzed cycloisomerization of allyl propargyl ether substrates. The reactivity and enantioselectivity of the reaction was shown to be highly dependent on the chiral skeleton of the ligand structures with ee's ranging from 22-99 %. The proton source had a significant impact on the enantioselectivity. The generation of palladium hydride from formic acid led to the highest ee. A selectivity model based on a proposed transition state was used to predict and explain the enantiomeric outcome of the reaction.

Keywords
Cyclization, Isomerization, Enynes, N, P ligands, Palladium, Density functional calculations
National Category
Organic Chemistry
Research subject
Organic Chemistry
Identifiers
urn:nbn:se:su:diva-133232 (URN)10.1002/ejoc.201600468 (DOI)000380138100023 ()
Available from: 2016-09-12 Created: 2016-09-05 Last updated: 2017-12-28Bibliographically approved

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