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Asymmetric Catalysis in a Micro Reactor: Ce, Yb and Lu Catalysed Enantioselective Addition of Trimethylsilyl Cyanide to Benzaldehyde
KTH, Superseded Departments, Chemistry.
KTH, Superseded Departments, Chemistry.
Department of Chemistry, University of Hull.
KTH, Superseded Departments, Chemistry.ORCID iD: 0000-0002-1743-7650
2004 (English)In: Tetrahedron, ISSN 0040-4020, E-ISSN 1464-5416, Vol. 60, no 46, 10515-10520 p.Article in journal (Refereed) Published
Abstract [en]

A T-shaped micro reactor was used for the optimisation of reaction conditions for the enantioselective silyleyanation of benzaldehyde catalysed by lanthanide-pybox complexes. Compared to a conventional batch procedure, higher conversion was observed within shorter reaction time. The micro reactor process involving Lu(III) afforded essentially the same enantioselectivity as the batch process (73 vs 76% ee), whereas the enantioselectivity was lower in the micro reactor for catalysts containing Yb(III) (53 compared to 72%). Ce(III) provided very low selectivity in both types of processes (1 and 11 % ee, respectively). A study of the effect of additives showed that the enantioselectivity in the Yb catalysed reaction performed in the micro reactor could be increased to 66%, whereas only a minor improvement, to 78% ee, was observed in the reaction with Lu.

Place, publisher, year, edition, pages
2004. Vol. 60, no 46, 10515-10520 p.
Keyword [en]
Asymmetric metal catalysis; Lanthanide; Micro reactor; Pybox; Silylcyanations; benzaldehyde; cerium; cyanide; lanthanide; lutetium; trimethylsilyl derivative; ytterbium; addition reaction; article; asymmetric catalysis; catalyst; chemical analysis; chemical structure; cyanation; enantioselectivity; priority journal; reaction analysis; reactor; structure analysis
National Category
Organic Chemistry
Identifiers
URN: urn:nbn:se:kth:diva-6919DOI: 10.1016/j.tet.2004.08.080ISI: 000224632300015Scopus ID: 2-s2.0-4944237872OAI: oai:DiVA.org:kth-6919DiVA: diva2:11766
Note
QC 20100809 QC 20110916Available from: 2007-03-22 Created: 2007-03-22 Last updated: 2011-09-16Bibliographically approved
In thesis
1. Efficient Synthesis and Analysis of Chiral Cyanohydrins
Open this publication in new window or tab >>Efficient Synthesis and Analysis of Chiral Cyanohydrins
2007 (English)Doctoral thesis, comprehensive summary (Other scientific)
Abstract [en]

This thesis deals with the development of new methods for efficient synthesis and analysis in asymmetric catalysis. It focuses on the preparation of chiral cyanohydrins by enantioselective addition of cyanide to prochiral aldehydes.

The initial part of the thesis describes the development of a dual Lewis acid– Lewis base activation system for efficient synthesis of chiral O-acylated and Ocarbonylated cyanohydrins. This system was used for the preparation of a variety of cyanohydrins in high isolated yields and with up to 96% ee. Activation of the cyanide by nucleophilic attack of the Lewis base at the carbonyl carbon atom was supported experimentally.

Secondly, convenient procedures for the synthesis of polymer-bound chiral YbCl3-pybox and Ti-salen complexes are described. The polymeric complexes were employed in cyanation of benzaldehyde.

A T-shaped microreactor was used for screening of reaction conditions for the enantioselective cyanation of benzaldehyde using trimethylsilyl cyanide and acetyl cyanide as cyanide sources. A microreactor charged with the polymeric Tisalen complex was used for enantioselective cyanation of benzaldehyde.

Finally, an enzymatic method for high throughput analysis of ee and conversion of products from chiral Lewis acid–Lewis base-catalysed additions of α- ketonitriles to prochiral aldehydes was developed. The method could be used for the analysis of a variety of O-acylated cyanohydrins. Microreactor technology was successfully combined with high throughput analysis for efficient catalyst optimisation.

Place, publisher, year, edition, pages
Stockholm: KTH, 2007. 54 p.
Series
Trita-CHE-Report, ISSN 1654-1081 ; 2007:11
Keyword
asymmetric catalysis, cyanohydrins, microreactor, polymersupported catalyst, ketonitriles, titanium, lanthanide, Lewis acid, Lewis base
National Category
Organic Chemistry
Identifiers
urn:nbn:se:kth:diva-4315 (URN)978-91-7178-599-2 (ISBN)
Public defence
2007-04-13, Sal F3, KTH, Lindstedtsvägen 26, Stockholm, 10:15 (English)
Opponent
Supervisors
Note
QC 20100809Available from: 2007-03-22 Created: 2007-03-22 Last updated: 2010-08-09Bibliographically approved

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