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Palladium Catalysis in Directed C-H Bond Activation and Cycloisomerisation Reactions
Stockholm University, Faculty of Science, Department of Organic Chemistry.ORCID iD: 0000-0001-9329-0091
2020 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The main focus of this thesis concerns the development of Pd(II)-catalysed synthetic methodologies for the preparation of biologically active compounds.

In the first part (paper I-III), unactivated C–H bonds of a cyclobutane derivative are selectively functionalised using a directing group starting from the feedstock compound verbenone (paper I). In the following part the development of an efficient transamidation protocol for the directing group removal is reported (paper II). Both procedures were then used in conjunction, for the synthesis of diverse C-3 arylated benzofuran-2-carboxylamides, in only 3 steps starting from benzofuran-2-carboxylic acid (paper III).

The second part (paper IV-V) aimed to evaluate the catalytic efficiency of the heterogeneous catalyst Pd(II)-AmP-MCF in the intramolecular hydroamination of propargylic carbamates. The catalyst was able to promote the formation of various 1,3-oxazolidin-2-ones in high yields, at room temperature with low palladium loadings (paper IV). This investigation is followed by a mechanistic study of the Pd(II)-AmP-MCF catalyst’s deactivation process during a lactone formation, using X-ray absorption spectroscopy (paper V).

Place, publisher, year, edition, pages
Stockholm: Department of Organic Chemistry, Stockholm University , 2020. , p. 58
Keywords [en]
Palladium(II), Catalysis, C-H Functionalisation, Transamidation, XAS
National Category
Organic Chemistry
Research subject
Organic Chemistry
Identifiers
URN: urn:nbn:se:su:diva-180981ISBN: 978-91-7911-170-0 (print)ISBN: 978-91-7911-171-7 (electronic)OAI: oai:DiVA.org:su-180981DiVA, id: diva2:1426157
Public defence
2020-06-05, 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At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 5: Manuscript.

Available from: 2020-05-13 Created: 2020-04-23 Last updated: 2020-05-26Bibliographically approved
List of papers
1. Convenient Access to Chiral Cyclobutanes with Three Contiguous Stereocenters from Verbenone by Directed C(sp(3))-H arylation
Open this publication in new window or tab >>Convenient Access to Chiral Cyclobutanes with Three Contiguous Stereocenters from Verbenone by Directed C(sp(3))-H arylation
2019 (English)In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 25, no 20, p. 5154-5157Article in journal (Refereed) Published
Abstract [en]

This work demonstrates how a series of complex, chiral cyclobutane derivatives can be accessed in four steps from the terpene verbenone through the application of a directed C-H functionalization approach. The developed synthetic route involved an 8-aminoquinoline-directed C(sp(3))-H arylation as the key step, and this reaction could be carried out with a wide range of aryl and heteroaryl iodides to furnish a variety of cyclobutane products with three contiguous stereocenters. Moreover, it was shown that the 8-aminoquinoline auxiliary could be effectively removed from the cyclobutane derivatives using an ozonolysis-based cleavage method.

Keywords
8-aminoquinoline, C(sp(3))-H functionalization, cyclobutanes, palladium, verbenone
National Category
Organic Chemistry
Research subject
Organic Chemistry
Identifiers
urn:nbn:se:su:diva-170158 (URN)10.1002/chem.201806416 (DOI)000468855200007 ()30716181 (PubMedID)
Available from: 2019-06-25 Created: 2019-06-25 Last updated: 2020-04-27Bibliographically approved
2. A Two-Step Procedure for the Overall Transamidation of 8-Aminoquinoline Amides Proceeding via the Intermediate N-Acyl-Boc-Carbamates
Open this publication in new window or tab >>A Two-Step Procedure for the Overall Transamidation of 8-Aminoquinoline Amides Proceeding via the Intermediate N-Acyl-Boc-Carbamates
2018 (English)In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 83, no 8, p. 4464-4476Article in journal (Refereed) Published
Abstract [en]

Herein a two-step strategy for achieving overall transamidation of 8-aminoquinoline amides has been explored. In this protocol, the 8-aminoquinoline amides were first treated with Boc(2)O and DMAP to form the corresponding N-acyl-Boc-carbamates, which were found to be sufficiently reactive to undergo subsequent aminolysis with different amines in the absence of any additional reagents or catalysts. To demonstrate the utility of this approach, it was applied on a number of 8-aminoquinoline amides from the recent C-H functionalization literature, enabling access to a range of elaborate amide derivatives in good to high yields

National Category
Organic Chemistry
Research subject
Organic Chemistry
Identifiers
urn:nbn:se:su:diva-156672 (URN)10.1021/acs.joc.8b00174 (DOI)000430898500015 ()29578345 (PubMedID)
Available from: 2018-06-01 Created: 2018-06-01 Last updated: 2020-04-27Bibliographically approved
3. Synthesis of Elaborate Benzofuran-2-Carboxamide Derivatives through a Combination of 8-Aminoquinoline Directed C–H Arylation and Transamidation Chemistry
Open this publication in new window or tab >>Synthesis of Elaborate Benzofuran-2-Carboxamide Derivatives through a Combination of 8-Aminoquinoline Directed C–H Arylation and Transamidation Chemistry
2020 (English)In: Molecules, ISSN 1420-3049, E-ISSN 1420-3049, Vol. 25, no 2, article id 361Article in journal (Refereed) Published
Abstract [en]

Herein, we present a short and highly modular synthetic route that involves 8-aminoquinoline directed C–H arylation and transamidation chemistry, and which enables access to a wide range of elaborate benzofuran-2-carboxamides. For the directed C–H arylation reactions, Pd catalysis was used to install a wide range of aryl and heteroaryl substituents at the C3 position of the benzofuran scaffold in high efficiency. Directing group cleavage and further diversification of the C3-arylated benzofuran products were then achieved in a single synthetic operation through the utilization of a one-pot, two-step transamidation procedure, which proceeded via the intermediate N-acyl-Boc-carbamates. Given the high efficiency and modularity of this synthetic strategy, it constitutes a very attractive method for generating structurally diverse collections of benzofuran derivatives for small molecule screening campaigns.

Keywords
palladium, C–H functionalization, 8-aminoquinoline, benzofuran, transamidation
National Category
Organic Chemistry
Research subject
Organic Chemistry
Identifiers
urn:nbn:se:su:diva-180978 (URN)10.3390/molecules25020361 (DOI)000515381800123 ()
Available from: 2020-04-22 Created: 2020-04-22 Last updated: 2020-04-25Bibliographically approved
4. Efficient 1,3-Oxazolidin-2-one Synthesis through Heterogeneous Pd-II-Catalyzed Intramolecular Hydroamination of Propargylic Carbamates
Open this publication in new window or tab >>Efficient 1,3-Oxazolidin-2-one Synthesis through Heterogeneous Pd-II-Catalyzed Intramolecular Hydroamination of Propargylic Carbamates
Show others...
2019 (English)In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 25, no 25, p. 6295-6299Article in journal (Refereed) Published
Abstract [en]

Herein, we present an operationally simple protocol for the cycloisomerization of propargylic carbamates in which a heterogeneous catalyst consisting of Pd species immobilized on amino-functionalized siliceous mesocellular foam (Pd-II-AmP-MCF) is used. This Pd nanocatalyst displayed high efficiency at low catalyst loading and reaction temperatures, which allowed for the efficient and mild synthesis of a wide range of 1,3-oxazolidin-2-one derivatives and related compounds. Moreover, it proved possible to re-use the Pd nanocatalyst for several reactions, although a gradual decrease in activity was observed in the subsequent cycles.

Keywords
cycloisomerization, heterogeneous catalysis, mesoporous silica, oxazolidinones, palladium
National Category
Organic Chemistry
Research subject
Organic Chemistry
Identifiers
urn:nbn:se:su:diva-171163 (URN)10.1002/chem.201900678 (DOI)000471033900007 ()30888694 (PubMedID)
Available from: 2019-08-08 Created: 2019-08-08 Last updated: 2020-04-27Bibliographically approved
5. In Situ XAS Investigation of the Deactivation and Reactivation Mechanisms of a Heterogeneous Palladium(II) catalyst during the Cycloisomerization of Acetylenic Acids
Open this publication in new window or tab >>In Situ XAS Investigation of the Deactivation and Reactivation Mechanisms of a Heterogeneous Palladium(II) catalyst during the Cycloisomerization of Acetylenic Acids
Show others...
2019 (English)Manuscript (preprint) (Other academic)
Abstract [en]

The cause and mechanism of deactivation of a well-studied heterogeneous palladium(II) catalyst in the intramolecular lactonization of acetylenic acids to γ-alkylidene lactones have been investigated. It was shown that the deactivation was driven by the formation of reduced palladium species following the addition of the base triethylamine. In this work, X-ray absorption spectroscopy (XAS) was used to identify the palladium species and follow their evolution over the course of the reaction. It was also found that the choice of substrates has significant influences on the Pd species under the same reaction conditions. With these insights into the deactivation mechanism derived from XAS, different strategies were tested and illustrated to regain or maintain the active state of the catalyst. This information was further used to develop a new protocol, which can effectively prevent the deactivation of the catalyst and prolong its usage. 

National Category
Chemical Sciences
Research subject
Inorganic Chemistry; Organic Chemistry
Identifiers
urn:nbn:se:su:diva-167289 (URN)
Available from: 2019-03-26 Created: 2019-03-26 Last updated: 2020-04-27Bibliographically approved

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