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Palladium-Catalyzed Electrophilic Substitution via Monoallylpalladium Intermediates
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.
2003 (English)In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 42, no 31, 3656-3658 p.Article in journal (Refereed) Published
Place, publisher, year, edition, pages
2003. Vol. 42, no 31, 3656-3658 p.
Keyword [en]
aldehydes, allylation, electrophilic substitution, homogenous catalysis, palladium
Identifiers
URN: urn:nbn:se:su:diva-22714DOI: 10.1002/anie.200351477OAI: oai:DiVA.org:su-22714DiVA: diva2:189307
Note
Part of urn:nbn:se:su:diva-105Available from: 2004-04-22 Created: 2004-04-22 Last updated: 2017-12-13Bibliographically approved
In thesis
1. Development of Palladium-Catalyzed Transformations Involving η1-Allypalladium Species
Open this publication in new window or tab >>Development of Palladium-Catalyzed Transformations Involving η1-Allypalladium Species
2004 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis is focused on investigation of the structure, reactivity and isomerization reactions of η1-allylpalladium complexes, which are key intermediates in catalytic transformations. The first part of this thesis concerns the structure and reactivity of bis-allylpalladium complexes. We have studied the regioselective palladium-catalyzed coupling reaction of various dialkylsubstituted allyl chlorides with allylstannanes and benzylidenemalonitrile, affording functionalized 1,7-octadienes. We have also found that benzylidenemalonitrile can be replaced by isocyanates providing bis-allylated amides. The second part is a computational study on the η3-η1-η3 isomerization of allylpalladium complexes. The mechanism of the isomerization was studied by DFT. It was found that the isomerization involves tetra-coordinated η1-allylpalladium intermediates. Alkyl substitution of the metalated carbon leads to destabilization of the η1-allylpalladium intermediate, which increases the activation energy of the isomerization process. The last part describes our efforts to extend the synthetic scope of mono-allylpalladium chemistry to include catalytic allylation of imine and aldehyde substrates. We have found that this reactivity can be achieved by the use of strongly coordinating tridentate ligands on palladium. The η1-allylpalladium intermediate has been observed by NMR-spectroscopy, and DFT calculations have been performed to show the feasibility of an electrophilic attack occuring on the allyl moiety.

Place, publisher, year, edition, pages
Stockholm: Institutionen för organisk kemi, 2004. 65 p.
Keyword
Palladium, Homogenous catalysis, Allylation, Electrophilic substitution, Density functional calculations
National Category
Organic Chemistry
Identifiers
urn:nbn:se:su:diva-105 (URN)91-7265-868-1 (ISBN)
Public defence
2004-05-14, Magnélisalen, Kemiska övningslaboratoriet, Svante Arrhenius väg 12 A, Stockholm, 10:00 (English)
Opponent
Supervisors
Available from: 2004-04-22 Created: 2004-04-22 Last updated: 2010-02-11Bibliographically approved
2. Employment of Palladium Pincer Complex Catalysts and Lewis Acids for Synthesis and Transformation of Organometallic Compounds
Open this publication in new window or tab >>Employment of Palladium Pincer Complex Catalysts and Lewis Acids for Synthesis and Transformation of Organometallic Compounds
2005 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis is mainly focused on the development of new palladium catalyzed transformations using so-called “pincer” complexes. These complexes were applied as catalysts in two important areas of organometallic chemistry: substitution of propargylic substrates by dimetallic reagents; and allylation of aldehydes and imines by allylstannanes. In addition, this thesis includes studies on Lewis acid mediated cyclization reactions of allylsilanes with aldehydes.

Pincer complex catalyzed substitution of various propargylic substrates could be achieved under mild conditions using tin and silicon based dimetallic reagents to obtain propargyl- and allenylstannanes and silanes. The regioselectivity of the substitution reaction strongly depends on the steric and electronic effects of the propargylic substrate. According to our mechanistic studies the key intermediate of the reaction is an organostannane (or silane) coordinated pincer complex. DFT modeling studies on the transfer of the trimethylstannyl functionality to the propargylic substrate revealed a novel mechanism, which is based on the unique topology of the pincer-complex catalysts.

Our further studies showed that palladium pincer complexes can be employed as efficient catalysts for electrophilic allylic substitution of allylstannanes with aldehyde and imine substrates. In contrast to previous applications for electrophilic allylic substitutions via bis-allylpalladium complexes, this reaction involves mono-allylpalladium intermediates which were observed by 1H-NMR spectroscopy.

The last chapter of this thesis is focused on Lewis-acid mediated cyclization of hydroxy functionalized allylsilanes, which afford tetrahydropyran derivatives with a high stereoselectivity.

Place, publisher, year, edition, pages
Stockholm: Institutionen för organisk kemi, 2005. 58 p.
National Category
Chemical Sciences
Identifiers
urn:nbn:se:su:diva-416 (URN)91-7155-026-7 (ISBN)
Public defence
2005-04-29, Magnélisalen, Kemiska övningslaboratoriet, Svante Arrhenius väg 12 A, Stockholm, 10:00 (English)
Opponent
Supervisors
Available from: 2005-03-24 Created: 2005-03-24 Last updated: 2010-02-11Bibliographically approved

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