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Iridium-catalysed asymmetric hydrogenation of allylic alcohols via dynamic kinetic resolution
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.
Stockholm University, Faculty of Science, Department of Organic Chemistry.
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2018 (English)In: Nature Catalysis, E-ISSN 2520-1158, Vol. 1, no 6, p. 438-443Article in journal (Refereed) Published
Abstract [en]

Dynamic kinetic resolutions (DKRs) allow for the conversion of both enantiomers of starting material into a single enantiomer  of product, hence avoiding the 50% yield limit observed in traditional kinetic resolutions. Transition-metal-catalysed variants have become an important and useful method in asymmetric synthesis. Here we report an asymmetric hydrogenation of allylic alcohols using an Ir–N,P-ligand complex via DKR. In contrast to the many DKRs involving carbonyl reduction, this methodology allows for DKR during alkene reduction. Mechanistic studies support the hypothesis that racemization of the substrate is achieved by cleavage and reforming of the oxygen–carbon bond. Under the cooperative dynamic kinetic asymmetric hydrogenation, a broad range of chiral alcohols containing two stereogenic centres were produced with excellent diastereoselectivities (up to 95:5) and enantioselectivities (up to 99%).

Place, publisher, year, edition, pages
2018. Vol. 1, no 6, p. 438-443
Keywords [en]
Asymmetric Hydrogenation
National Category
Organic Chemistry
Research subject
Organic Chemistry
Identifiers
URN: urn:nbn:se:su:diva-156338DOI: 10.1038/s41929-018-0070-0ISI: 000446615700015OAI: oai:DiVA.org:su-156338DiVA, id: diva2:1205049
Available from: 2018-05-09 Created: 2018-05-09 Last updated: 2018-11-12Bibliographically approved
In thesis
1. Development of Asymmetric Iridium Catalysed Hydrogenation Reactions
Open this publication in new window or tab >>Development of Asymmetric Iridium Catalysed Hydrogenation Reactions
2018 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The focus of the work presented in this thesis is the development of iridium-catalysed asymmetric hydrogenation reactions.

The first part of this thesis covers the development of dynamic kinetic resolution in asymmetric hydrogenation of chiral, racemic secondary allylic alcohols, which are converted to chiral saturated alcohols with high dr and ee. In this study, a wide range of substrates was successfully hydrogenated to give good results, with up to 95:5 dr and 99% ee. Moreover, a number of different allylic alcohol derivatives were also investigated and found to undergo the DKR of hydrogenation with good results.

The second part of this thesis is directed towards the development of regioselective asymmetric mono-hydrogenation of 1,4- and 1,5-disubstituted 1,4-cyclohexadienes. Under optimized hydrogenation conditions, high yield of regioselective mono-hydrogenated products and excellent enantioselectivity were observed in most cases. The usefulness of the reaction was demonstrated in the preparation of important chiral α,β-unsaturated ketones in good yield and excellent ee of up to 96%. Our novel method provides a general route to this important class of compounds.

The third part concerns the development of asymmetric hydrogenation of β-hydroxy silanes. It was observed that under hydrogenation conditions, β-hydroxy silanes undergo Peterson olefination to form terminal olefins which are then hydrogenated using an Ir catalyst. A new class of Ir-N,P catalysts were prepared and provided high yield with excellent ee in up to 99%. In addition, the reaction was highly chemoselective and could be tuned to hydrogenate either an olefin or a β-hydroxy silane depending on the choice of catalyst and reaction conditions.

The final part describes the asymmetric hydrogenation of enamides. A variety of oxazolidinone-enamides were prepared and evaluated in this reaction. High yields, (up to 99%) and excellent ee, (up to 99%) were obtained.

Place, publisher, year, edition, pages
Stockholm: Department of Organic Chemistry, Stockholm University, 2018. p. 70
Keywords
Asymmetric hydrogenation, Iridium catalyst, Peterson olefination, Dynamic Kinetic Resolution
National Category
Organic Chemistry
Research subject
Organic Chemistry
Identifiers
urn:nbn:se:su:diva-156339 (URN)978-91-7797-300-3 (ISBN)978-91-7797-301-0 (ISBN)
Public defence
2018-06-26, 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 1: Accepted. Paper 3: Manuscript. Paper 4: Manuscript.

Available from: 2018-06-01 Created: 2018-05-09 Last updated: 2018-06-04Bibliographically approved

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