- Merging Halogen-Atom Transfer (XAT) and Cobalt Catalysis to Override E2-Selectivity in the Elimination of Alkyl Halides: A Mild Route towardcontra-Thermodynamic Olefins
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We report here a mechanistically distinct tactic to carry E2-type eliminations on alkyl halides. This strategy exploits the interplay of α-aminoalkyl radical-mediated halogen-atom transfer (XAT) with desaturative cobalt catalysis. The methodology is high-yielding, tolerates many functionalities, and was used to access industrially relevant materials. In contrast to thermal E2 eliminations where unsymmetrical substrates give regioisomeric mixtures, this approach enables, by fine-tuning of the electronic and steric properties of the cobalt catalyst, to obtain high olefin positional selectivity. This unprecedented mechanistic feature has allowed access tocontra-thermodynamic olefins, elusive by E2 eliminations.
- Zhao, Huaibo,McMillan, Alastair J.,Constantin, Timothée,Mykura, Rory C.,Juliá, Fabio,Leonori, Daniele
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supporting information
p. 14806 - 14813
(2021/09/18)
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- Enzymatic kinetic resolution of 1,1-dioxo-2,3-dihydro-1H-1λ6-thiophen-3-ol via temporary derivatisation
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Following the thio-conjugate addition of (±)-9, its enantiomers were extremely efficiently discriminated using Novozym 435. The thio-differentiating unit may then be removed either under reductive conditions, using Raney nickel, or following an
- Morgan, Ben S.,Roberts, Stanley M.,Evans, Paul
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p. 5273 - 5276
(2007/10/03)
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- Oxygen-17 Nuclear Magnetic Resonance Spectral Investigation of 3-Alkoxy-trans-3,4-Disubstituted-Thiolane 1,1-Dioxides and Related Compounds
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The (17)O NMR spectra of 3-alkoxythiolane 1,1-dioxides indicate that the sulfonyl oxygens are diastereotopic but their chemical shift differences are essentially independent of the structure of the alkyl group in the alkoxy moiety.Eu(fod)3 enhances the (17)O chemical shift difference between the diastereotopic sulfonyl oxygens in 3-isopropoxythiolane 1,1-dioxide and shifts both oxygens upfield. α,β-Unsaturation deshields the sulfonyl oxygens in both five- and six-membered rings.
- Sammakia, Tarek H.,Harris, David L.,Evans, Slayton A.
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p. 747 - 752
(2007/10/02)
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