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Screening of Ligands in the Asymmetric Metallocenethiolatocopper(I)-Catalyzed Allylic Substitution with Grignard Reagents
Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
2006 (engelsk)Inngår i: Tetrahedron, ISSN 0040-4020, E-ISSN 1464-5416, Vol. 62, nr 24, s. 5632-5640Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

Screening of metallocenethiolate ligands for copper(I)-catalyzed substitution of allylic acetates with Grignard reagents has been carried out. The previously used ligand, lithium (R,Sp)-2-(1-dimethylaminoethyl)ferrocenylthiolate (4a), possessing both central and planar chirality, was the starting point for the screening. It was found that the diastereomeric ligand lithium (R,Rp)-2-(1-dimethylaminoethyl)ferrocenylthiolate (4b) exhibiting reversed planar chirality gave increased enantioselectivity in the allylic substitution, at least when cinnamyl acetate was used as a substrate. The ruthenocene-based ligand lithium (R,Sp)-2-(1-dimethylaminoethyl)ruthenocenylthiolate (4c) gave an enhanced reaction rate, but lower chiral induction. The use of disulfide bis[(R,Sp)-2-(1-dimethylaminoethyl)ferrocenyl]disulfide (7a) as a ligand precursor worked well but resulted in lower enantioselectivity.

sted, utgiver, år, opplag, sider
Elsevier Ltd , 2006. Vol. 62, nr 24, s. 5632-5640
Emneord [en]
Asymmetric induction; Copper catalysis; Allylic substitution; Cross-coupling; Ferrocene ligands
HSV kategori
Identifikatorer
URN: urn:nbn:se:su:diva-22681DOI: 10.1016/j.tet.2006.03.100OAI: oai:DiVA.org:su-22681DiVA, id: diva2:189259
Merknad
Part of urn:nbn:se:su:diva-1031Tilgjengelig fra: 2006-05-08 Laget: 2006-05-08 Sist oppdatert: 2017-12-13bibliografisk kontrollert
Inngår i avhandling
1. Asymmetric Synthesis and Mechanistic Studies on Copper(I)-Catalyzed Substitution of Allylic Substrates
Åpne denne publikasjonen i ny fane eller vindu >>Asymmetric Synthesis and Mechanistic Studies on Copper(I)-Catalyzed Substitution of Allylic Substrates
2006 (engelsk)Doktoravhandling, med artikler (Annet vitenskapelig)
Abstract [en]

This thesis deals with the copper-catalyzed substitution of allylic substrates.

In the first part of this thesis, the synthesis of a series of metallocenethiolates is described. The thiolates were examined as ligands in the enantioselective copper(I)-catalyzed γ-substitution of allylic acetates.

The second part describes a study on copper-catalyzed α-substitution of enantiomerically pure secondary allylic esters. It was observed that the degree of chirality transfer is strongly dependent on the reaction temperature. The loss of chiral information is consistent with an equilibration of the allylCu(III) intermediates prior to product formation, which is essential in order to realize a copper-catalyzed dynamic kinetic asymmetric transformation process.

The third part describes a study on copper-catalyzed stereoselective α-substitution of enantiopure acyclic allylic esters. This method, when combined, with ruthenium and enzyme catalyzed dynamic kinetic resolution of allylic alcohols, provides a straightforward route to pharmaceutically important α-methyl carboxylic acids.

The fourth part is a mechanistic study on the reaction of perfluoroallyl iodide with organocuprates. Experimental studies as well as theoretical calculations were used to explain the contrasting reactivity of perfluoroallyl iodide vs. allyl iodide in cuprate allylation reactions.

In the fifth part, the development of a practical and useful method for the preparation of pentasubstituted acylferrocenes is presented.

sted, utgiver, år, opplag, sider
Stockholm: Institutionen för organisk kemi, 2006. s. 53
Emneord
copper, allylic substitution, ferrocene, DYKAT, cross-coupling, homo-coupling, DFT
HSV kategori
Identifikatorer
urn:nbn:se:su:diva-1031 (URN)91-7155-280-4 (ISBN)
Disputas
2006-06-01, Magnélisalen, Kemiska övningslaboratoriet, Svante Arrhenius väg 12 A, Stockholm, 13:00
Opponent
Veileder
Tilgjengelig fra: 2006-05-08 Laget: 2006-05-08 Sist oppdatert: 2017-12-01bibliografisk kontrollert

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