| 1. |
- Ahlsten, Nanna, 1982-, et al.
(författare)
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A facile synthesis of α-fluoro ketones catalyzed by [Cp*IrCl2](2)
- 2011
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Ingår i: Synthesis (Stuttgart). - : Georg Thieme Verlag KG. - 0039-7881 .- 1437-210X. ; :16, s. 2600-2608
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Tidskriftsartikel (refereegranskat)abstract
- Allylic alcohols are isomerized into enolates (enols) by [Cp*IrCl2]2. The enolates react with Selectfluor present in the reaction media. This method produces α-fluoro ketones as single constitutional isomers in high yields.
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| 2. |
- Ahlsten, Nanna, et al.
(författare)
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Allylic alcohols as synthetic enolate equivalents : Isomerisation and tandem reactions catalysed by transition metal complexes
- 2012
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Ingår i: Dalton Transactions. - : Royal Society of Chemistry (RSC). - 1477-9226 .- 1477-9234. ; 41:6, s. 1660-1670
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Tidskriftsartikel (refereegranskat)abstract
- Allylic alcohols can be isomerised into carbonyl compounds by transition metal complexes. In the last few years, catalyst design and development have resulted in highly efficient isomerisations under mild reaction conditions, including enantioselective versions. In addition, the isomerisation of allylic alcohols has been combined with C-C bond forming reactions when electrophiles such as aldehydes or imines were present in the reaction mixture. Also, C-F bonds can be formed when electrophilic fluorinating reagents are used. Thus, allylic alcohols can be treated as latent enol(ate)s. In this article, we highlight the latest developments concerning the isomerisation of allylic alcohols into carbonyl compounds, focusing in particular on tandem isomerisation/C-C or C-heteroatom bond formation processes. Significant attention is given to the mechanistic aspects of the reactions.
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| 3. |
- Ahlsten, Nanna, 1982-, et al.
(författare)
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Ir-catalysed formation of C-F bonds. From allylic alcohols to α-fluoroketones
- 2011
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Ingår i: Chemical Communications. - : Royal Society of Chemistry (RSC). - 1359-7345 .- 1364-548X. ; 47:29, s. 8331-8333
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Tidskriftsartikel (refereegranskat)abstract
- A novel iridium-catalysed tandem isomerisation/C-F bond formation from allylic alcohols and Selectfluor® to prepare α-fluorinated ketones as single constitutional isomers is reported.
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| 4. |
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| 5. |
- Ahlsten, Nanna, et al.
(författare)
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Rhodium-catalysed coupling of allylic, homoallylic, and bishomoallylic alcohols with aldehydes and N-tosylimines
- 2010
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Ingår i: Abstracts of Papers, 239th ACS National Meeting, San Francisco, CA, United States, March 21-25, 2010. - : American Chemical Society.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 6. |
- Ahlsten, Nanna, 1982-, et al.
(författare)
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Rhodium-catalysed coupling of allylic, homoallylic, and bishomoallylic alcohols with aldehydes and N-tosylimines : insights into the mechanism
- 2009
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Ingår i: Advanced Synthesis and Catalysis. - : Wiley. - 1615-4150 .- 1615-4169. ; 351:16, s. 2657-2666
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Tidskriftsartikel (refereegranskat)abstract
- The isomerisation of alkenols followed by reaction with aldehydes or N-tosylimines catalysed by rhodium complexes has been studied. The catalytically active rhodium complex is formed in situ from commercially available (cyclooctadiene)rhodium(l) chloride dimer [Rh(COD)Cl](2). The tandem process affords aldol and Mannich-type products in excellent yields. The key to the success of the coupling reaction is the activation of the catalysts by reaction with postassium tert-butoxide (t-BuOK), which promotes a catalytic cycle via alkoxides rather than rhodium hydrides. This mechanism minimises the formation of unwanted by-products. The mechanism has been studied by (1)H NMR spectroscopy and deuterium labelling experiments.
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| 7. |
- Ahlsten, Nanna, 1982-, et al.
(författare)
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Rhodium-catalysed isomerisation of allylic alcohols in water at ambient temperature
- 2010
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Ingår i: Green Chemistry. - : Royal Society of Chemistry (RSC). - 1463-9262 .- 1463-9270. ; 12:9, s. 1628-1633
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Tidskriftsartikel (refereegranskat)abstract
- An environmentally benign method for the transformation of allylic alcohols into carbonyl compounds is described. Using [Rh(COD(CH3CN)(2)]BF4 (2) in combination with 1,3,5-triaza-7-phosphaadamantane (PTA, 1) as the catalytic system in water results in a very fast redox isomerisation of a variety of secondary allylic alcohols at ambient temperature. Also, some primary allylic alcohols can be isomerised into the corresponding aldehydes. The active complex, which in some cases can be used in catalyst loadings as low as 0.5 mol%, is formed in situ from commercially available reagents. Based on deuterium labelling studies, a tentative mechanism involving metal-enone intermediates is presented.
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| 8. |
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| 9. |
- Ahlsten, Nanna
(författare)
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Transition metal-catalysed enol formation from allylic alcohols : Isomerisation, C−C and C−F bond formations
- 2011
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis describes the isomerisation of allylic alcohols into enols and enolates catalysed by transition metal complexes. The transformation has been used to prepare both unsubstituted and α-substituted carbonyl compounds. Significant attention has been given to the mechanistic aspects of the reactions. In the first part of this thesis, an environmentally benign procedure for the redox isomerisation of allylic alcohols into ketones is described. The reaction takes place in water and at room temperature using a cationic rhodium complex in combination with water-soluble phosphines. A variety of allylic alcohols could be isomerised in high yields using this procedure. The second part describes the combination of an allylic alcohol isomerisation with a C−C bond formation, catalysed by a rhodium complex. In this way, allylic alcohols were coupled with aldehydes and N-tosyl imines forming aldol and Mannich-type products. In addition, homoallylic and bishomoallylic alcohols were for the first time isomerised into the corresponding enolates and coupled using this methodology. In the third part of this thesis, the isomerisation of allylic alcohols was coupled with a C−F bond formation using an iridium complex and electrophilic fluorinating reagents. This novel transformation was used to convert allylic alcohols into single regioisomers of α-fluoroketones. The reaction is tolerant to air and water and takes place at room temperature. All of the reactions described take place under mild conditions, are operationally simple, and utilise catalysts formed in situ from commercially available metal complexes and ligands.
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| 10. |
- Ahlsten, Nanna, 1982-
(författare)
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Transition metal-catalysed isomerisation of allylic alcohols : Applications to C−C, C−F and C−Cl bond formation
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The focus of this thesis has been to develop selective and atom-economical methods for carbon-carbon and carbon-heteroatom bond formation, and to some extent improve on existing findings in this area. More specifically, methods for the catalytic generation of enolates from allylic alcohols and their in situ functionalisation with electrophilic reagents are described. In the first part of this thesis, a method for the Rh-catalysed redox-isomerisation of allylic alcohols into carbonyl compounds under environmentally benign conditions is described. The reaction takes place at room temperature, in the absence of acids or bases, using water as the only solvent, and it is applicable to both primary and secondary allylic alcohols.The second part describes the combination of an isomerisation reaction of allylic alcohols with a C−C bond formation, catalysed by a rhodium complex. In this way, allylic alcohols were coupled with aldehydes and N-tosylimines to give aldol and Mannich-type products. In addition to allylic alcohols, homoallylic and bishomoallylic alcohols could be used as enolate precursors, and this is the first report where the latter two substrate types have been used in such a reaction. In the remaining parts of the thesis, an iridium-catalysed isomerisation of allylic alcohols has been combined with an electrophilic halogenation step to provide a conceptually new method for the synthesis of α-halogenated carbonyl compounds. In this way, α-fluoro and α-chloroketones have been synthesised as single constitutional isomers, with the regiochemistry of the final products determined by the position of the double bond in the allylic alcohols. The reactions are tolerant to air, run in water-organic solvent mixtures, and proceed at room temperature.
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