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Minor enantiomer recycling: Metal catalyst, organocatalyst and biocatalyst working in concert
KTH, School of Chemical Science and Engineering (CHE), Chemistry.
KTH, School of Biotechnology (BIO).
KTH, School of Chemical Science and Engineering (CHE), Chemistry.
KTH, School of Biotechnology (BIO).
Show others and affiliations
2009 (English)In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 15, no 44, 12107-12113 p.Article in journal (Refereed) Published
Abstract [en]

 A minor enantiomer recycling one-pot procedure employing two reinforcing chiral catalysts has been developed. Continuous regeneration of the achiral starting material is effected via selective enzyme-catalyzed hydrolysis of the minor product enantiomer from Lewis acid-Lewis base catalyzed addition of acyl cyanides to prochiral aldehydes in a two-phase solvent system. The process provides O-acylated cyanohydrins in close to perfect enantioselectivities, higher than those obtained in the direct process, and in high yields. A combination of a (SS)salen Ti Lewis acid and Candida antarctica lipase B provides the products with R absolute configuration, whereas the opposite enantiomer is obtained from the (R,R)-salen Ti complex and Candida rugosa lipase.

Place, publisher, year, edition, pages
2009. Vol. 15, no 44, 12107-12113 p.
Keyword [en]
asymmetric catalysis, enantioselectivity, enzyme catalysis, Lewis acids, organocatalysis
National Category
Chemical Sciences
Identifiers
URN: urn:nbn:se:kth:diva-10365DOI: 10.1002/chem.200901338ISI: 000272109100036Scopus ID: 2-s2.0-72949121762OAI: oai:DiVA.org:kth-10365DiVA: diva2:216255
Note
QC 20100922. Uppdaterad från Manuskript till Artikel (20100922). Tidigare titel "Minor Enantiomer Recycling: Metal Catalyst and Biocatalyst Working in Concert".Available from: 2009-05-07 Created: 2009-05-07 Last updated: 2017-12-13Bibliographically approved
In thesis
1. New Methods for Chiral Cyanohydrin Synthesis
Open this publication in new window or tab >>New Methods for Chiral Cyanohydrin Synthesis
2009 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis deals with method development in asymmetric catalysis and specifically syntheses of enantioenriched O-functionalized cyanohydrins.

The first part describes the development of a method for the synthesis of O‑alkoxycarbonylated and O-acylated cyanohydrins. Ethyl cyanoformate and acyl cyanides were added to aldehydes in a reaction catalyzed by a chiral dimeric Ti-salen complex together with a tertiary amine. High yields and enantioselectivities were in most cases obtained. Mechanistic studies were performed and a reaction mechanism was proposed. ­

The second part describes a method in which the undesired minor enantiomer in a Lewis acid–Lewis base-catalyzed acylcyanation is continuously recycled into prochiral starting material. Close to enantiopure O‑acylated cyanohydrins were obtained in high yields.

The third part deals with asymmetric acylcyanations of ketones. Acetyl cyanide was found to add to α‑ketoesters in a reaction catalyzed by a chiral Lewis base. Yields up to 77% and 82% ee were obtained.

The final part describes an enzymatic method for high-throughput analysis of O‑acylated cyanohydrins. The enantiomeric excess and conversion were determined for products obtained from a number of aromatic and aliphatic aldehydes.

Place, publisher, year, edition, pages
Stockholm: KTH, 2009. 54 p.
Series
Trita-CHE-Report, ISSN 1654-1081 ; 2009:12
Keyword
acyl cyanides, asymmetric synthesis, biocatalysis, cyanide, cyanohydrins, dual activation, enzymes, high-throughput screening, Lewis acid, Lewis base, metal catalysis, minor enantiomer recycling, salen, titanium
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-10205 (URN)978-91-7415-263-0 (ISBN)
Public defence
2009-05-08, F3, Lindstedtsvägen 26, Stockholm, 10:00 (English)
Opponent
Supervisors
Note
QC 20100818Available from: 2009-05-07 Created: 2009-04-06 Last updated: 2010-09-22Bibliographically approved
2. 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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