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Asymmetric Transfer Hydrogenation of Aromatic Ketones: Catalyst Development and Mechanistic Studies
Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Kemiska institutionen, Avdelningen för organisk kemi.
2002 (engelsk)Doktoravhandling, med artikler (Annet vitenskapelig)
Abstract [en]

This thesis describes the development and evaluation of new chiral Ru(arene)(amino alcohol) catalysts for the transfer hydrogenation of aromatic ketones using isopropanol as the hydrogen source. Two mechanistic studies of the Ru(arene)(amino alcohol) catalyzed transfer hydrogenation of acetophenone were also conducted.

The Ru(arene)[(1S,3R,4R)-3.(Hydroxymethyl)-2-azabicyclo[2.2.1]heptane] catalyst was optimized for catalytic asymmetric transfer hydrogenation of aromatic ketones. The effect of substituents on the arene ligand on both selectivity and reactivity was investigated. The performance of the catalyst was also optimized by altering the structure of the chiral amino alcohol ligand. These optimizations resulted in a highly active and selective catalyst, Ru(p-cymene)[(R)-1-[(1S,2R,6S,7R,9R)-4,4-Dimethyl-3,5-dioxa-8-aza-tricyclo[5.2.1.00,0]dec-9-yl]-ethanol], for asymmetric transfer hydrogenation of aromatic ketones. This catalyst was capable of reducing acetophenone in 96% ee in 4 minutes at room temperature at a substrate to catalyst ratio of 200. Full conversion was reached even at a substrate to catalyst ratio of 5000 and the high enantioselectivity of 96% ee was maintained. A range of prochiral aromatic ketones with electron withdrawing or electron donating substituents in any position on the aromatic ring were reduced in short reaction times and with high enantioselectivity, up to 99% ee. Bulky aryl alkyl ketones were also reduced with high enantioselectivity.

A combined quantum chemical and kinetic investigation of the Ru(arene)(amino alcohol) catalyzed transfer hydrogenation of acetophenone was conducted. Three possible mechanisms were studied and the quantum chemical calculations indicated that the mechanism was concerted. In addition, a kinetic isotope study for the Ru(arene)(amino alcohol) catalyzed transfer hydrogenation of acetophenone was conducted. The determination of the kinetic isotope effect of the proton and hydride transfer showed that the proton and the hydride transfer were both rate-limiting and occurred in the same step. This result supports the proposed concerted mechanism.

sted, utgiver, år, opplag, sider
Uppsala: Acta Universitatis Upsaliensis , 2002. , s. 49
Serie
Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1104-232X ; 730
Emneord [en]
Organic chemistry, transfer hydrogenation, aza-norbornyl structure, amino acid derivatives, amino alcohols, ruthenium, concerted mechanism, asymmetric catalysis.
Emneord [sv]
Organisk kemi
HSV kategori
Forskningsprogram
organisk kemi
Identifikatorer
URN: urn:nbn:se:uu:diva-2151ISBN: 91-554-5348-1 (tryckt)OAI: oai:DiVA.org:uu-2151DiVA, id: diva2:161807
Disputas
2002-06-07, The Svedberg salen, Kemikum, Uppsala, 13:15
Opponent
Tilgjengelig fra: 2002-05-17 Laget: 2002-05-17bibliografisk kontrollert
Delarbeid
1. Ru(arene)(amino alcohol)-Catalyzed Transfer Hydrogenation of Ketones: Mechanism and Origin of Enantioselectivity
Åpne denne publikasjonen i ny fane eller vindu >>Ru(arene)(amino alcohol)-Catalyzed Transfer Hydrogenation of Ketones: Mechanism and Origin of Enantioselectivity
1999 (engelsk)Inngår i: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 121, nr 41, s. 9580-9588Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

The mechanism of the Ru(arene)(amino alcohol)-catalyzed transfer hydrogenation of ketones using isopropyl alcohol as the hydrogen source has been studied by means of hybrid density functional methods (B3PW91). Three mechanistic alternatives were evaluated, and it was shown that the reaction takes place via a six-membered transition state, where a metal-bound hydride and a proton of a coordinated amine are transferred simultaneously to the ketone. Further calculations provided a general rationale for the rate of the reaction by comparison of steric effects in the ground and transition states of the ruthenium hydride complex. It was found that the TS has a strong preference for planarity, and this in turn is dependent on the conformational behavior of the O,N-linkage of the amino alcohol ligand. Finally, a general model, rationalizing the enantioselectivity of the reaction, was developed. Experimental studies of both rate and enantioselectivity were used in order to support the computational results.

HSV kategori
Identifikatorer
urn:nbn:se:uu:diva-89926 (URN)10.1021/ja9906610 (DOI)
Tilgjengelig fra: 2002-05-17 Laget: 2002-05-17 Sist oppdatert: 2017-12-14bibliografisk kontrollert
2. Evidence for Concerted Proton and Hydride Transfer in the Ru(cymene)(amino alcohol)-Catalyzed Transfer Hydrogenation
Åpne denne publikasjonen i ny fane eller vindu >>Evidence for Concerted Proton and Hydride Transfer in the Ru(cymene)(amino alcohol)-Catalyzed Transfer Hydrogenation
Manuskript (Annet vitenskapelig)
Identifikatorer
urn:nbn:se:uu:diva-89927 (URN)
Tilgjengelig fra: 2002-05-17 Laget: 2002-05-17 Sist oppdatert: 2010-01-13bibliografisk kontrollert
3. New Expidient Route to Both Enantiomers of Nonproteinogenic Amino Acid Derivatives from the Unsaturated 2-Aza-bicyclo Moiety. D. A
Åpne denne publikasjonen i ny fane eller vindu >>New Expidient Route to Both Enantiomers of Nonproteinogenic Amino Acid Derivatives from the Unsaturated 2-Aza-bicyclo Moiety. D. A
Vise andre…
1999 Inngår i: J. Org. Chem., Vol. 64, s. 2276-Artikkel i tidsskrift (Fagfellevurdert) Published
Identifikatorer
urn:nbn:se:uu:diva-89928 (URN)
Tilgjengelig fra: 2002-05-17 Laget: 2002-05-17bibliografisk kontrollert
4. 2-Azanorbornyl alcohols: Very efficient Ligands for Ruthenium-Catalyzed Asymmetric Transfer Hydrogenation of Aromatic Ketones. D. A
Åpne denne publikasjonen i ny fane eller vindu >>2-Azanorbornyl alcohols: Very efficient Ligands for Ruthenium-Catalyzed Asymmetric Transfer Hydrogenation of Aromatic Ketones. D. A
Vise andre…
1999 Inngår i: J. Org. Chem., Vol. 65, s. 3116-Artikkel i tidsskrift (Fagfellevurdert) Published
Identifikatorer
urn:nbn:se:uu:diva-89929 (URN)
Tilgjengelig fra: 2002-05-17 Laget: 2002-05-17bibliografisk kontrollert
5. Highly Diastereoselective Reaction of 2-Azanorbornyl Enolates with Electrophiles. D. A
Åpne denne publikasjonen i ny fane eller vindu >>Highly Diastereoselective Reaction of 2-Azanorbornyl Enolates with Electrophiles. D. A
1999 Inngår i: Org. Lett., Vol. 1, s. 1595-Artikkel i tidsskrift (Fagfellevurdert) Published
Identifikatorer
urn:nbn:se:uu:diva-89930 (URN)
Tilgjengelig fra: 2002-05-17 Laget: 2002-05-17bibliografisk kontrollert
6. Remote Dipole Effects as a Means to Accelerate Ru(Amino alcohol)-Catalyzed Transfer Hydrogenations of Ketones.
Åpne denne publikasjonen i ny fane eller vindu >>Remote Dipole Effects as a Means to Accelerate Ru(Amino alcohol)-Catalyzed Transfer Hydrogenations of Ketones.
Vise andre…
2001 Inngår i: Chem. Eur. J, Vol. 7, s. 1431-Artikkel i tidsskrift (Fagfellevurdert) Published
Identifikatorer
urn:nbn:se:uu:diva-89931 (URN)
Tilgjengelig fra: 2002-05-17 Laget: 2002-05-17bibliografisk kontrollert

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