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Chiral Lewis base catalyzed enantioselective acetylcyanation of α-oxo esters
KTH, School of Chemical Science and Engineering (CHE), Chemistry.
KTH, School of Chemical Science and Engineering (CHE), Chemistry.
KTH, School of Chemical Science and Engineering (CHE), Chemistry.
KTH, School of Chemical Science and Engineering (CHE), Chemistry.ORCID iD: 0000-0002-1743-7650
2009 (English)In: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, Vol. 23, 3917-3922 p.Article in journal (Refereed) Published
Abstract [en]

Acetyl cyanide adds to alkyl benzoylformates and to 2-oxoalkanoates to yield enantioenriched acylated cyanohydrins in one step in the presence of a catalytic amount of a chiral base. The reaction is accelerated by Lewis acids and by the addition of a catalytic amount of methanol. Under optimized conditions, 94% of a 94:6 mixture of the O-acetylated and non-protected cyanohydrins was formed from, methyl benzoylformate in the presence of cinchonidine; from, this mixture the acylated compound with 66% ee was isolated in 77% yield. Ethyl pyruvate and ierf-butyl 2-oxobutanoate were more reactive, and essentially full conversion to the products with 69 and 82% ee, respectively, was achieved. The reaction proceeds by a non-selective addition of cyanide ion to give the non-protected cyanohydrin followed by a dynamic kinetic resolution to provide the enantioenriched acetylated product.

Place, publisher, year, edition, pages
2009. Vol. 23, 3917-3922 p.
Keyword [en]
Acylation; Addition reactions; Asymmetric catalysis; Cyanides; Kinetic resolution; Lewis bases
National Category
Organic Chemistry
Identifiers
URN: urn:nbn:se:kth:diva-10366DOI: 10.1002/ejoc.200900055ISI: 000269103600014Scopus ID: 2-s2.0-68049139704OAI: oai:DiVA.org:kth-10366DiVA: diva2:216256
Note

Tidigare titel: Chiral Lewis Base-Catalyzed Enantioselective Acetylcyanation of α-Ketoesters QC 20100818

Available from: 2009-05-07 Created: 2009-05-07 Last updated: 2016-12-19Bibliographically 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

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Moberg, Christina

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