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Application and further structure elucidation of Pd(0)-CalB CLEA biohybrid catalyst- Chemoenzymatic dynamic kinetic resolution of primary benzylic amines
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 Materials and Environmental Chemistry (MMK).
Show others and affiliations
(English)Manuscript (preprint) (Other academic)
National Category
Organic Chemistry
Research subject
Organic Chemistry
Identifiers
URN: urn:nbn:se:su:diva-153897OAI: oai:DiVA.org:su-153897DiVA, id: diva2:1188354
Available from: 2018-03-07 Created: 2018-03-07 Last updated: 2018-03-20Bibliographically approved
In thesis
1. Heterogeneous catalysis in racemization and kinetic resolution along a journey in protein engineering
Open this publication in new window or tab >>Heterogeneous catalysis in racemization and kinetic resolution along a journey in protein engineering
2018 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The first part of my thesis concerns the use of heterogeneous acidic resins for racemization of tert-alcohols without any side-product formation. The focus was to develop a system which can be further extended to a DKR protocol consisting of an enzymatic KR reaction. Based on our knowledge of the resins, an unexpected migratory DKR protocol turned out to be an efficient method for the synthesis of carbocyclic allylic carbinols.

The development of enzyme and metal catalyst hybrids was already an ongoing theme in our group. A supporter-free biohybrid catalyst was developed which can be used in several different types of reactions. The Pd(0)-CalB CLEA catalyst was applied in a two-step-cascade transformation and in the DKR of benzylic primary amines. The catalyst was characterized by different analytical techniques, to understand its composition and structure.

The enzymes have always been the main focus of the studies and therefore wild type enzymes were initially utilized. However, these natural biocatalysts are associated with certain limitations. In contrast, protein engineering allows for enzymes to be modified and optimized. We have used the technique to create a subtilisin Carlsberg mutant, which was studied both by modeling and in vitro. The mutant was found to catalyze the (S)-selective transesterification of sec-alcohols containing long aliphatic carbon chains, and it also exhibited higher performance in organic solvent.

The last project concerned the protein engineering of CalA enzyme towards tert-alcohols. The kinetic resolution of tert-alcohols with this enzyme is very slow but it occurs with good enantioselectivity. The aim was therefore to improve the activity of CalA via protein engineering. Seven amino acids were mutated close to the active site and a library was created based on our prediction. Throughout the screening, a few variants showed higher activity, which were sequenced and further analyzed in the transesterification of tert-alcohols.

Place, publisher, year, edition, pages
Stockholm: Department of Organic Chemistry, Stockholm University, 2018. p. 81
Keyword
racemization, protein engineering, kinetic resolution, heterogeneous catalysis, biohybrid catalyst
National Category
Organic Chemistry
Research subject
Organic Chemistry
Identifiers
urn:nbn:se:su:diva-153921 (URN)978-91-7797-185-6 (ISBN)978-91-7797-186-3 (ISBN)
Public defence
2018-04-26, 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 4: Manuscript. Paper 6: Manuscript.

Available from: 2018-04-03 Created: 2018-03-08 Last updated: 2018-03-23Bibliographically approved
2. Studies on Metalloenzymatic Dynamic Kinetic Resolutions and Iron-Catalyzed Reactions of Allenes
Open this publication in new window or tab >>Studies on Metalloenzymatic Dynamic Kinetic Resolutions and Iron-Catalyzed Reactions of Allenes
2018 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The main focus of this thesis lies in the development of new transition metal-catalyzed chemoenzymatic dynamic kinetic resolutions (DKR) of both alcohols and amines. The first part of the thesis deals with the development of new heterogeneous systems for the DKR of amines. The racemization catalysts in these different systems are all composed of palladium nanoparticles supported on either mesoporous silica or incorporated in a biocomposite that is composed of a bioactive cross-linked enzyme aggregate. 

The second part of the thesis deals with the development of a homogeneous iron catalyst in the racemization of sec-alcohols for the implementation in a chemoenzymatic DKR. Two protocols for the racemization of sec-alcohols are reported. The first one could not be combined with a chemoenzymatic kinetic resolution, although this was overcome in the second iron based protocol. 

Following the successful iron catalyzed chemoenzymatic DKR of sec-alcohols, the iron catalyst was used in the cyclization of α-allenic alcohols and N-protected amines to furnish 2,3-dihydrofurans and 2,3-dihydropyrroles, respectively. The cyclization is proceeding in a diastereoselective manner.

The last part of the thesis deals with attempts to further elucidate the mechanism of activation of a known ruthenium racemization catalyst. X-ray absorption spectroscopy using synchrotron radiation was used for this purpose.

Place, publisher, year, edition, pages
Stockholm: Department of Organic Chemistry, Stockholm University, 2018. p. 97
Keyword
Racemization, Dynamic Kinetic Resolution, Enzyme Catalysis, XAS, Asymmetric Synthesis
National Category
Organic Chemistry
Research subject
Organic Chemistry
Identifiers
urn:nbn:se:su:diva-153952 (URN)978-91-7797-195-5 (ISBN)978-91-7797-196-2 (ISBN)
Public defence
2018-04-27, 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 4: Manuscript. Paper 7: Manuscript. Paper 8: Manuscript.

Available from: 2018-04-04 Created: 2018-03-09 Last updated: 2018-03-22Bibliographically approved

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Gustafson, Karl P. J.Görbe, Tamásde Gonzalo Calvo, GonzaloYuan, NingSchreiber, CynthiaTai, Cheuk-WaiBäckvall, Jan-Erling
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