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Ruthenium-Catalyzed Hydrogen Transfer Reactions: Mechanistic Studies and Chemoenzymatic Dynamic Kinetic Resolutions
Stockholm University, Faculty of Science, Department of Organic Chemistry.
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The main focus of this thesis lies on transition metal-catalyzed hydrogen transfer reactions. In the first part of the thesis, the mechanism for racemization of sec-alcohols with a ruthenium complex, Ru(CO)2Cl(η5-C5Ph5) was studied.

The reaction between 5-hexen-2-ol and Ru(CO)2(Ot-Bu)(η5-C5Ph5) was studied with the aim to elucidate the origin of the slow racemization observed for this sec-alcohol. Two diastereomers of an alkoxycarbonyl complex, which has the double bond coordinated to ruthenium, were characterized by NMR and in situ FT-IR spectroscopy. The observed inhibition of the rate of racemization for substrates with double bonds provided further confirmation of the importance of a free coordination site on ruthenium for β-hydride elimination. Furthermore, we observed that CO exchange, monitored by 13C NMR using 13CO, occurs with both the precatalyst, Ru(CO)2Cl(η5-C5Ph5), and the active catalytic intermediate, Ru(CO)2(Ot-Bu)(η5-C5Ph5). It was also found that added CO has an inhibitory effect on the rate of racemization of (S)-1-phenylethanol. Both these observations provide strong support for reversible CO dissociation as a key step in the racemization mechanism.

In the second part of this thesis, Ru(CO)2Cl(η5-C5Ph5) was combined with an enzymatic resolution catalyzed by a lipase, leading to several efficient dynamic kinetic resolutions (DKR). DKR of exocyclic allylic alcohols afforded the corresponding acetates in high yields and with excellent enantiomeric excess (ee). The products were utilized as synthetic precursors for α-substituted ketones and lactones. DKR of a wide range of homoallylic alcohols afforded the products in good to high yields and with high ee. The homoallylic acetates were transformed into 5,6-dihydropyran-2-ones in a short reaction sequence. Furthermore, DKR of a wide range of aromatic β-chloroalcohols afforded the products in high yields and with excellent ee. The β-chloro acetates were further transformed into chiral epoxides.

Place, publisher, year, edition, pages
Stockholm: Department of Organic Chemistry, Stockholm University , 2013. , 84 p.
Keyword [en]
Hydrogen transfer, ruthenium catalysis, kinetic resolution, dynamic kinetic resolution, racemization, asymmetric synthesis
National Category
Natural Sciences
Research subject
Organic Chemistry
Identifiers
URN: urn:nbn:se:su:diva-89263ISBN: 978-91-7447-706-1 (print)OAI: oai:DiVA.org:su-89263DiVA: diva2:616629
Public defence
2013-05-24, 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 2: Manuscript. Paper 5: Mansucript.

Available from: 2013-04-18 Created: 2013-04-17 Last updated: 2013-11-06Bibliographically approved
List of papers
1. Unexpected formation of a cyclopentadienylruthenium alkoxycarbonyl complex with a coordinated C=C bond
Open this publication in new window or tab >>Unexpected formation of a cyclopentadienylruthenium alkoxycarbonyl complex with a coordinated C=C bond
2009 (English)In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 131, no 38, 13622-13624 p.Article in journal (Refereed) Published
Place, publisher, year, edition, pages
American Chemical Society, 2009
National Category
Organic Chemistry
Identifiers
urn:nbn:se:su:diva-30232 (URN)10.1021/ja905741w (DOI)000270186600027 ()
Available from: 2009-10-07 Created: 2009-10-07 Last updated: 2017-12-13Bibliographically approved
2. Racemization of Olefinic Alcohols by a Cyclopentadienyl Ruthenium Carbonyl Complex: Study of the Inhibiting Effect of the Carbon-Carbon Double Bond
Open this publication in new window or tab >>Racemization of Olefinic Alcohols by a Cyclopentadienyl Ruthenium Carbonyl Complex: Study of the Inhibiting Effect of the Carbon-Carbon Double Bond
(English)Manuscript (preprint) (Other academic)
National Category
Natural Sciences
Identifiers
urn:nbn:se:su:diva-89260 (URN)
Available from: 2013-04-17 Created: 2013-04-17 Last updated: 2013-04-18Bibliographically approved
3. CO dissociation mechanism in racemization of alcohols by a cyclopentadienyl ruthenium dicarbonyl catalyst
Open this publication in new window or tab >>CO dissociation mechanism in racemization of alcohols by a cyclopentadienyl ruthenium dicarbonyl catalyst
2011 (English)In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 133, no 9, 2820-2823 p.Article in journal (Refereed) Published
Abstract [en]

13CO exchange studies of racemization catalyst (η5-Ph5C5)Ru(CO)2Cl and (η5-Ph5C5)Ru(CO)2(Ot-Bu) by 13C NMR spectroscopy are reported. CO exchange for the active catalyst form, (η5-Ph5C5)Ru(CO)2(Ot-Bu) is approximately 20 times faster than that for the precatalyst (η5-Ph5C5)Ru(CO)2Cl. An inhibition on the rate of racemization of (S)-1-phenylethanol was observed on addition of CO. These results support the hypothesis that CO dissociation is a key step in the racemization of sec-alcohols by (η5-Ph5C5)Ru(CO)2Cl, as also predicted by DFT calculations.

National Category
Organic Chemistry
Research subject
Organic Chemistry
Identifiers
urn:nbn:se:su:diva-59869 (URN)10.1021/ja1098066 (DOI)000289455200008 ()
Funder
Swedish Research CouncilKnut and Alice Wallenberg Foundation
Available from: 2011-07-20 Created: 2011-07-20 Last updated: 2017-12-08Bibliographically approved
4. Enantioselective Route to Ketones and Lactones from Exocyclic Allylic Alcohols via Metal and Enzyme Catalysis
Open this publication in new window or tab >>Enantioselective Route to Ketones and Lactones from Exocyclic Allylic Alcohols via Metal and Enzyme Catalysis
2012 (English)In: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 14, no 19, 5094-5097 p.Article in journal (Refereed) Published
Abstract [en]

A general and efficient route for the synthesis of enantiomerically pure a-substituted ketones and the corresponding lactones has been developed. Ruthenium- and enzyme-catalyzed dynamic kinetic resolution (DKR) with a subsequent Cu-catalyzed alpha-allylic substitution are the key steps of the route. The a-substituted ketones were obtained in high yields and with excellent enantiomeric excess. The methodology was applied to the synthesis of a naturally occurring caprolactone, (R)-10-methyl-6-undecanolide, via a subsequent Baeyer-Villiger oxidation.

National Category
Organic Chemistry
Identifiers
urn:nbn:se:su:diva-82136 (URN)10.1021/ol302358j (DOI)000309438400030 ()
Funder
Swedish Research CouncilKnut and Alice Wallenberg Foundation
Note

AuthorCount:4;

Available from: 2012-11-09 Created: 2012-11-08 Last updated: 2017-12-07Bibliographically approved
5. Dynamic Kinetic Resolution of Homoallylic Alcohols: Application to the Synthesis of Enantiomerically Pure 5,6-Dihydropyran-2-ones and delta-Lactones
Open this publication in new window or tab >>Dynamic Kinetic Resolution of Homoallylic Alcohols: Application to the Synthesis of Enantiomerically Pure 5,6-Dihydropyran-2-ones and delta-Lactones
Show others...
2013 (English)In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 19, no 41, 13859-13864 p.Article in journal (Refereed) Published
Abstract [en]

Dynamic kinetic resolution of various homoallylic alcohols with the use of Candida antarctica lipaseB and ruthenium catalyst 2 afforded homoallylic acetates in high yields and with high enantioselectivity. These enantiopure acetates were further transformed into homoallylic acrylates after hydrolysis of the ester function and subsequent DMAP-catalyzed esterification with acryloyl chloride. After ring-closing metathesis 5,6-dihydropyran-2-ones were obtained in good yields. Selective hydrogenation of the carboncarbon double bond afforded the corresponding -lactones without loss of chiral information.

Keyword
dynamic kinetic resolution, homoallylic alcohols, lactones, racemization, ruthenium catalysis
National Category
Organic Chemistry
Identifiers
urn:nbn:se:su:diva-95745 (URN)10.1002/chem.201301980 (DOI)000325135800031 ()
Funder
Swedish Research CouncilKnut and Alice Wallenberg Foundation
Note

AuthorCount:5;

Available from: 2013-11-06 Created: 2013-11-04 Last updated: 2017-12-06Bibliographically approved
6. Highly efficient route for enantioselctive preparation of chlorohydrins via dynamic kinetic resolution
Open this publication in new window or tab >>Highly efficient route for enantioselctive preparation of chlorohydrins via dynamic kinetic resolution
2008 (English)In: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 10, no 21, 4807-4810 p.Article in journal (Refereed) Published
Abstract [en]

Dynamic kinetic resolution (DKR) of various aromatic chlorohydrins with the use of Pseudomonas cepacia lipase (PS-C “Amano” II) and ruthenium catalyst 1 afforded chlorohydrin acetates in high yields and high enantiomeric excesses. These optically pure chlorohydrin acetates are useful synthetic intermediates and can be transformed to a range of important chiral compounds.

National Category
Organic Chemistry
Identifiers
urn:nbn:se:su:diva-15314 (URN)10.1021/ol801749z (DOI)000260534500025 ()
Available from: 2009-01-05 Created: 2009-01-05 Last updated: 2017-12-13Bibliographically approved

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