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Minor Enantiomer Recycling-Effect of Two Reinforcing Catalysts on Product Yield and Enantiomeric Excess
KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. KTH, School of Biotechnology (BIO), Biochemistry. KTH, School of Biotechnology (BIO), Centres, Albanova VinnExcellence Center for Protein Technology, ProNova.
KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
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2010 (English)In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 2, no 6, 683-693 p.Article in journal (Refereed) Published
Abstract [en]

Kinetic modeling of a recycling procedure in which the minor product enantiomer from an enantioselective catalytic reaction is selectively retransformed to starting material by a second chiral catalyst demonstrates that the enantiomeric excess of the product is not affected by the relative amounts of the two catalysts, but that the yield increases when the amount of the catalyst for the product-forming reaction is increased. The yield, but not the enantiomeric excess, is also affected by the initial substrate concentration. The recycling process is compared to sequential processes in which either the second catalyst is added after completion of the first reaction or in which the two catalysts are added simultaneously. In the sequential processes, high enantioselectivity can be obtained at the expense of product yield, whereas under recycling conditions both high enantiomeric excess and high yield can be achieved. Experimental data from a recycling procedure providing qualitative support for results from kinetic modeling are presented.

Place, publisher, year, edition, pages
2010. Vol. 2, no 6, 683-693 p.
Keyword [en]
asymmetric catalysis, biocatalysis, enantioselectivity, kinetic modeling, metal catalyst
National Category
Organic Chemistry
Identifiers
URN: urn:nbn:se:kth:diva-46653DOI: 10.1002/cctc.200900327ISI: 000279479100016Scopus ID: 2-s2.0-79957822367OAI: oai:DiVA.org:kth-46653DiVA: diva2:454680
Funder
Swedish Research CouncilKnut and Alice Wallenberg Foundation
Note
QC 20111108Available from: 2011-11-08 Created: 2011-11-04 Last updated: 2017-12-08Bibliographically approved
In thesis
1. Development and Studies of the Processes Involved in Minor Enantiomer Recycling
Open this publication in new window or tab >>Development and Studies of the Processes Involved in Minor Enantiomer Recycling
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis describes the development and rationalization of processes involved in a new methodology developed in our group, minor enantiomer recycling.

The first part of the thesis addresses mechanistic studies of one of the reactions involved in minor enantiomer recycling, dual Lewis acid-Lewis base catalyzed acetylcyanation of aldehydes. The methodology uses a combination of a chiral titanium-salen  complex with a tertiary amine as a catalytic  system  in  the enantioselective  synthesis  of  O-acylated  cyanohydrins from aldehydes and ketonitriles. Mechanistic investigations revealed that the rate-determining step in the reaction changes, depending on the nature of the aldehyde that was used. It was also concluded that cyanohydrin is coordinated to the Lewis acid in the acylation step.

The second part of the thesis deals with minor enantiomer recycling, a highly selective one-pot recycling system. In a first step the product is formed as a minor and a major enantiomer by asymmetric catalysis. Recycling of the minor enantiomer, by selective kinetic resolution, regenerates the starting material. Continuous addition of a second reagent, also involved in a coupled exergonic process, leads to an increase of both yield and enantiomeric excess. Recycling procedures for the synthesis of O-acylated and O-formylated cyanohydrins have been developed with high yield and high enantiomeric excess of the products. The study includes development of the systems, comparison to other methodologies in asymmetric catalysis, and attempts to understand the processes involved.

 

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2014. 66 p.
Series
TRITA-CHE-Report, ISSN 1654-1081 ; 2014:53
Keyword
asymmetric catalysis, biocatalysis, cyanohydrins, dual activation, Lewis acid, Lewis base, minor enantiomer recycling, recycling, titanium
National Category
Organic Chemistry
Research subject
Chemistry
Identifiers
urn:nbn:se:kth:diva-156635 (URN)978-91-7595-338-0 (ISBN)
Public defence
2014-12-18, F3, Lindstedtsvägen 26, KTH, Stockholm, 13:00 (English)
Opponent
Supervisors
Note

QC 20141202

Available from: 2014-12-02 Created: 2014-12-01 Last updated: 2014-12-02Bibliographically approved

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Moberg, Christina

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