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Transition Metal Hydrides: Biomimetic Studies and Catalytic Applications
Stockholm University, Faculty of Science, Department of Organic Chemistry.
2007 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

In this thesis, studies of the nature of different transition metal-hydride complexes are described. The first part deals with the enantioswitchable behaviour of rhodium complexes derived from amino acids, applied in asymmetric transfer hydrogenation of ketones. We found that the use of amino acid thio amide ligands resulted in the formation of the R-configured product, whereas the use of the corresponding hydroxamic acid- or hydrazide ligands selectively gave the S-alcohol.

Structure/activity investigations revealed that the stereochemical outcome of the catalytic reaction depends on the ligand mode of coordination.

In the second part, an Fe hydrogenase active site model complex with a labile amine ligand has been synthesized and studied. The aim of this study was to find a complex that efficiently catalyzes the reduction of protons to molecular hydrogen under mild conditions. We found that the amine ligand functions as a mimic of the loosely bound ligand which is part of the active site in the hydrogenase.

Further, an Fe hydrogenase active site model complex has been coupled to a photosensitizer with the aim of achieving light induced hydrogen production. The redox properties of the produced complex are such that no electron transfer from the photosensitizer part to the Fe moiety occurs.

In the last part of this thesis, the development of a protocol for the transfer hydrogenation of ketones to secondary alcohols without the involvement of transition metal catalysts is described. A variety of ketones were efficiently reduced in 2-propanol using catalytic amounts of alkali alkoxide under microwave irradiation.

Place, publisher, year, edition, pages
Stockholm: Institutionen för organisk kemi , 2007.
Keyword [en]
transition metals, catalysis, bioinorganic chemistry, hydrides
National Category
Organic Chemistry
Research subject
Organic Chemistry
Identifiers
URN: urn:nbn:se:su:diva-7187ISBN: 978-91-7155-539-7 (print)OAI: oai:DiVA.org:su-7187DiVA: diva2:197808
Public defence
2007-12-14, Magnélisalen, Kemiska övningslaboratoriet, Svante Arrhenius väg 12 A, Stockholm, 10:00 (English)
Opponent
Supervisors
Available from: 2007-11-22 Created: 2007-11-14 Last updated: 2015-10-18Bibliographically approved
List of papers
1. A Simple and Efficient Catalyst System for the Asymmetric Transfer Hydrogenation of Ketones
Open this publication in new window or tab >>A Simple and Efficient Catalyst System for the Asymmetric Transfer Hydrogenation of Ketones
2007 (English)In: Synlett: Accounts and Rapid Communications in Synthetic Organic Chemistry, ISSN 0936-5214, E-ISSN 1437-2096, no 16, 2541-2544 p.Article in journal (Refereed) Published
Keyword
alcohols (benzene compounds);reduction, hydrogenation;diastereoselective syntheses, enantioselective syntheses (incl. cis/trans-isomerism)
National Category
Organic Chemistry
Identifiers
urn:nbn:se:su:diva-24562 (URN)10.1002/chin.200808080 (DOI)000250300100015 ()
Available from: 2007-11-22 Created: 2007-11-14 Last updated: 2017-12-13Bibliographically approved
2. Asymmetric Transfer Hydrogenation of Ketones Catalyzed by Amino Acid Derived Rhodium Complexes: On the Origin of Enantioselectivity and Enantioswitchability
Open this publication in new window or tab >>Asymmetric Transfer Hydrogenation of Ketones Catalyzed by Amino Acid Derived Rhodium Complexes: On the Origin of Enantioselectivity and Enantioswitchability
Show others...
2009 (English)In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 15, no 42, 11197-11209 p.Article in journal (Refereed) Published
Abstract [en]

Amino acid based thioamides, hydroxamic acids, and hydrazides have been evaluated as ligands in the rhodium-catalyzed asymmetric transfer hydrogenation of ketones in 2-propanol. Catalysts containing thioamide ligands derived from L-valine were found to selectively generate the product with an R configuration (95 % ee), whereas the corresponding L-valine-based hydroxamic acids or hydrazides facilitated the formation of the (S)-alcohols (97 and 91 % ee, respectively). The catalytic reduction was examined by performing a structure–activity correlation investigation with differently functionalized or substituted ligands and the results obtained indicate that the major difference between the thioamide and hydroxamic acid based catalysts is the coordination mode of the ligands. Kinetic experiments were performed and the rate constants for the reduction reactions were determined by using rhodium–arene catalysts derived from amino acid thioamide and hydroxamic acid ligands. The data obtained show that the thioamide-based catalyst systems demonstrate a pseudo-first-order dependence on the substrate, whereas pseudo-zero-order dependence was observed for the hydroxamic acid containing catalysts. Furthermore, the kinetic experiments revealed that the rate-limiting steps of the two catalytic systems differ. From the data obtained in the structure–activity correlation investigation and along with the kinetic investigation it was concluded that the enantioswitchable nature of the catalysts studied originates from different ligand coordination, which affects the rate-limiting step of the catalytic reduction reaction.

Keyword
amino acids, asymmetric catalysis, kinetics;reaction mechanisms, rhodium
National Category
Organic Chemistry
Identifiers
urn:nbn:se:su:diva-35766 (URN)10.1002/chem.200900548 (DOI)000271560000020 ()
Note
"Corrigendum" in Chemistry - A European Journal 2010, vol 16, nr 35, sid 10610.Available from: 2010-01-22 Created: 2010-01-20 Last updated: 2017-12-12Bibliographically approved
3. Dynamic Ligation at the First Amine-coordinated Iron Hydrogenase Active Site Mimic
Open this publication in new window or tab >>Dynamic Ligation at the First Amine-coordinated Iron Hydrogenase Active Site Mimic
2006 In: Chemical Communications, ISSN 1359-7345, no 40, 4206-4208 p.Article in journal (Refereed) Published
Identifiers
urn:nbn:se:su:diva-24564 (URN)
Note
Part of urn:nbn:se:su:diva-7187Available from: 2007-11-22 Created: 2007-11-14Bibliographically approved
4. Bio Inspired Side-on Attachment of a Ruthenium Photo-sensitizer to an Iron Hydrogenase Active Site Model
Open this publication in new window or tab >>Bio Inspired Side-on Attachment of a Ruthenium Photo-sensitizer to an Iron Hydrogenase Active Site Model
Show others...
2006 In: Dalton Transactions, ISSN 1477-9226, no 38, 4599-4606 p.Article in journal (Refereed) Published
Identifiers
urn:nbn:se:su:diva-24565 (URN)
Note
Part of urn:nbn:se:su:diva-7187Available from: 2007-11-22 Created: 2007-11-14Bibliographically approved
5. A Simple and Efficient Catalytic Method for the Reduction of Ketones
Open this publication in new window or tab >>A Simple and Efficient Catalytic Method for the Reduction of Ketones
2007 (English)In: Advanced Synthesis and Catalysis, ISSN 1615-4150, E-ISSN 1615-4169, Vol. 349, no 10, 1609-1613 p.Article in journal (Refereed) Published
Abstract [en]

A range of ketones was efficiently reduced in the presence of catalytic amounts of lithium isopropoxide in 2-propanol under microwave heating, with alcohol products being formed in yields up to 99 %.

Keyword
alkali metals, hydrogen transfer, ketones, microwave heating, reduction
National Category
Organic Chemistry
Research subject
Organic Chemistry
Identifiers
urn:nbn:se:su:diva-25594 (URN)10.1002/adsc.200700091 (DOI)000248365300009 ()
Available from: 2008-11-13 Created: 2008-11-13 Last updated: 2017-12-13Bibliographically approved

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