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Bifunctional Pybox Ligands: Application in Cyanations of Benzaldehyde
KTH, Skolan för kemivetenskap (CHE), Kemi.
KTH, Skolan för kemivetenskap (CHE), Kemi.
KTH, Skolan för kemivetenskap (CHE), Kemi.
KTH, Skolan för kemivetenskap (CHE), Kemi.
Vise andre og tillknytning
(engelsk)Manuskript (Annet vitenskapelig)
HSV kategori
Identifikatorer
URN: urn:nbn:se:kth:diva-7127OAI: oai:DiVA.org:kth-7127DiVA, id: diva2:12044
Merknad
QC 20100709Tilgjengelig fra: 2007-05-16 Laget: 2007-05-16 Sist oppdatert: 2010-07-09bibliografisk kontrollert
Inngår i avhandling
1. Impact of Secondary Interactions in Asymmetric Catalysis
Åpne denne publikasjonen i ny fane eller vindu >>Impact of Secondary Interactions in Asymmetric Catalysis
2007 (engelsk)Doktoravhandling, med artikler (Annet vitenskapelig)
Abstract [en]

This thesis deals with secondary interactions in asymmetric catalysis and their impact on the outcome of catalytic reactions.

The first part revolves around the metal-catalyzed asymmetric allylic alkylation reaction and how interactions within the catalyst affect the stereochemistry. An OH–Pd hydrogen bond in Pd(0)–π-olefin complexes of hydroxy-containing oxazoline ligands was identified by density functional theory computations and helped to rationalize the contrasting results obtained employing hydroxy- and methoxy-containing ligands in the catalytic reaction. This type of hydrogen bond was further studied in phenanthroline metal complexes. As expected for a hydrogen bond, the strength of the bond was found to increase with increased electron density at the metal and with increased acidity of the hydroxy protons.

The second part deals with the use of hydroxy- and methoxy-containing phosphinooxazoline ligands in the rhodium- and iridium-catalyzed asymmetric hydrosilylation reaction. The enantioselectivities obtained were profoundly enhanced upon the addition of silver salts. This phenomenon was explained by an oxygen–metal coordination in the catalytic complexes, which was confirmed by NMR studies of an iridium complex. Interestingly, the rhodium and iridium catalysts nearly serve as pseudo-enantiomers giving products with different absolute configurations.

The final part deals with ditopic pyridinobisoxazoline ligands and the application of their metal complexes in asymmetric cyanation reactions. Upon complexation, these ligands provide catalysts with both Lewis acidic and Lewis basic sites, capable of activating both the substrate and the cyanation reagent. Lanthanide and aluminum complexes of these ligands were found to catalyze the addition of the fairly unreactive cyanation reagents ethyl cyanoformate and acetyl cyanide to benzaldehyde, whereas complexes of ligands lacking the Lewis basic coordination sites failed to do so.

sted, utgiver, år, opplag, sider
Stockholm: KTH, 2007. s. 60
Serie
Trita-CHE-Report, ISSN 1654-1081 ; 2007: 29
Emneord
asymmetric catalysis, secondary interaction, hydrogen bond, chiral ligand, allylic alkylation, hydrosilylation, cyanation, pymox, box, PHOX, pybox, palladium, iridium, rhodium, Lewis acid, Lewis base
HSV kategori
Identifikatorer
urn:nbn:se:kth:diva-4380 (URN)978-91-7178-676-0 (ISBN)
Disputas
2007-06-01, D3, D, Lindstedtsv. 5, Stockholm, 10:00
Opponent
Veileder
Merknad
QC 20100709Tilgjengelig fra: 2007-05-16 Laget: 2007-05-16 Sist oppdatert: 2010-07-09bibliografisk kontrollert

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