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New Efficient Ruthenium Catalysts for Racemization of Alcohols at Room Temperature
Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
2004 (Engelska)Ingår i: Tetrahedron Letters, ISSN 0040-4039, E-ISSN 1359-8562, Vol. 45, nr 36, s. 6799-6802Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

5-Pentaphenylcyclopentadienyl)RuCl(CO)2 was found to catalyze efficiently the racemization of chiral alcohols such as (S)-1-phenylethanol, (S)-1-phenylpropan-2-ol, (S)-4-phenylbutan-2-ol and (S)-4-methoxy-1-phenylethanol at room temperature in the presence of a base. The catalytic activity of three other Ru(II) complexes was also investigated. The effects of halide and solvent were studied as well.

Ort, förlag, år, upplaga, sidor
2004. Vol. 45, nr 36, s. 6799-6802
Nationell ämneskategori
Organisk kemi
Identifikatorer
URN: urn:nbn:se:su:diva-24330DOI: 10.1016/j.tetlet.2004.07.013OAI: oai:DiVA.org:su-24330DiVA, id: diva2:197245
Tillgänglig från: 2007-05-30 Skapad: 2007-05-23 Senast uppdaterad: 2017-12-13Bibliografiskt granskad
Ingår i avhandling
1. Synthetic Transformations via Metal- and Enzyme-Catalyzed Dynamic Kinetic Resolution
Öppna denna publikation i ny flik eller fönster >>Synthetic Transformations via Metal- and Enzyme-Catalyzed Dynamic Kinetic Resolution
2007 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
Abstract [en]

This thesis deals with the preparation of a new half-sandwich type ruthenium(II)- catalyst for racemization of optically active secondary alcohols and the development of a highly efficient method in combination with lipases such as Candida antarctica lipase B and Pseudomonas cepacia lipase for dynamic kinetic resolution of various functionalized alcohols under mild reaction conditions.

It was shown that the RuCl(CO)25-C5Ph5) complex can racemize optically active aliphatic and aromatic secondary alcohols at room temperature in rather short times. Different parameters, such as the nature of the catalyst, catalyst loading and solvent effect were studied. After the optimization steps, the Ru-catalyzed racemization of (S)-1-phenylethanol in the presence of Candida antarctica lipase B was also investigated. The compatibility of the metal- and enzyme-catalyzed reactions led to a highly efficient coupled catalytic system for transformation of racemic alcohols to their enantiomerically pure acetates. This protocol was applied for a wide range of secondary alcohols. It was shown that in the case of allylic alcohols the obtained enantiopure allylic acetates are useful compounds for synthesis of α-methyl carboxylic acids such as (R)-Flurbiprofen and acyloin acetates. Highly selective dynamic kinetic asymmetric transformation of 3,5-piperidine diol to deliver various 3,5-dioxygenated piperidines is also described.

Ort, förlag, år, upplaga, sidor
Stockholm: Institutionen för organisk kemi, 2007. s. 66
Nyckelord
ruthenium, racemization, lipase, dynamic kinetic resolution, secondary alcohol, Candida antarctica lipase B
Nationell ämneskategori
Organisk kemi
Forskningsämne
organisk kemi
Identifikatorer
urn:nbn:se:su:diva-6876 (URN)978-91-7155-463-5 (ISBN)
Disputation
2007-06-20, Magnélisalen, Arrheniuslaboratoriet, Svante Arrhenius väg 12, Stockholm, 10:00
Opponent
Handledare
Tillgänglig från: 2007-05-30 Skapad: 2007-05-23 Senast uppdaterad: 2017-10-16Bibliografiskt granskad
2. Studies of Biomimtic Oxidations and Racemizations
Öppna denna publikation i ny flik eller fönster >>Studies of Biomimtic Oxidations and Racemizations
2004 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
Abstract [en]

This thesis deals with studies of ruthenium-catalyzed hydrogen transfer reactions for oxidations and racemization.

Through optimisation of the substrate-selective redox catalyst, the electron and proton transfer mediator (a benzoquinone derivative), and the oxygen-activating metal macrocycle a highly efficient biomimetic oxidation of secondary alcohols was obtained. Several alcohols were subjected to the new oxidation protocol and the corresponding ketones were isolated in high yield.

The deactivation of the oxygen-activating metal macrocycle retarded the aerobic oxidation of primary alcohols. Encapsulation of the metal macrocycle into zeolite, described in chapter 3, proved to be an efficient method to solve this problem and comparable conversion of alcohols was achieved. The immobilization of the oxygen-activating porphyrin to a surface can be an alternative approach to solve the deactivation problem. Therefore as the first step towards studies of immobilized porphyrins on a metal surface (of gold or silver), S-thioacetyl derivatized porphyrins were synthesized; two alternative syntheses are described in chapter 4.

A new and effecient ruthenium-catalyzed racemization protocol was established by proper ligand tuning. The racemization of the enantiomerically pure alcohols was increased significantly; this work is reported in chapter 5.

Ort, förlag, år, upplaga, sidor
Stockholm: Institutionen för organisk kemi, 2004. s. 52
Nyckelord
oxidation of alcohols, ruthenium, porphyrin, racemization
Nationell ämneskategori
Organisk kemi
Identifikatorer
urn:nbn:se:su:diva-71 (URN)91-7265-819-3 (ISBN)
Disputation
2004-04-01, Magnélisalen, Arrheniuslaboratoriet, Svante Arrhenius väg 12 A, Stockholm, 14:00
Opponent
Handledare
Tillgänglig från: 2004-03-11 Skapad: 2004-03-11 Senast uppdaterad: 2013-08-15Bibliografiskt granskad

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