- E-Olefins through intramolecular radical relocation
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Full control over the selectivity of carbon-carbon double-bond migrations would enable access to stereochemically defined olefins that are central to the pharmaceutical, food, fragrance, materials, and petrochemical arenas. The vast majority of double-bond migrations investigated over the past 60 years capitalize on precious-metal hydrides that are frequently associated with reversible equilibria, hydrogen scrambling, incomplete E/Z stereoselection, and/or high cost. Here, we report a fundamentally different, radical-based approach.We showcase a nonprecious, reductant-free, and atom-economical nickel (Ni)(I)-catalyzed intramolecular 1,3-hydrogen atom relocation to yield E-olefins within 3 hours at room temperature. Remote installations of E-olefins over extended distances are also demonstrated.
- Kapat, Ajoy,Sperger, Theresa,Guven, Sinem,Schoenebeck, Franziska
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- ISOMERIZATION OF ALKENES
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The present invention relates to an isomerization method for alkenes, comprising of reaction an alkene with a Ni(I)-compound. By this method, E-Alkenes are obtained in excellent yield.
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Page/Page column 20-21; 22
(2020/04/25)
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- Concave reagents. 20. Sterically shielded m-terphenyls as selective agents in general protonations
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New m-terphenyls with acidic substituants in the 2′-position have been used in general protonations leading to reagent-controlled selectivity enhancements: up to 96:4 for the γ/α-protonation of unsymmetrically substituted allyl anions, up to 97:3 for the protonation of cyclohexyl anions generating preferentially the thermodynamically less stable cis-products. In order to allow a general, reagent-controlled protonation the acidity of the protonating agent should be as low as possible.
- Luening,Baumgartner,Manthey,Meynhardt
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p. 7922 - 7926
(2007/10/03)
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- ORGANOCOPPER(I) MEDIATED SYNTHESIS OF 1-ALKENYLSILANES AND 1,3-ALKADIENYLSILANES FROM ETHYNYLSILANES
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Ethynylsilanes (I) are converted into α-silyl substituted (Z)-alkenylcopper(I) compounds (II) by treatment with RCu reagents.The adducts II react with a variety of electrophiles to give the 1-alkenylsilanes RCH=C(E)SiR3' (III: E = H, Cl, Br, I, CN, SnMe3, SMe, Me, H2C=CHCH2).The conversion of I into III (E = H) can also be effected by using homocuprates, R2CuMgCl, and triorganodicuprates, R3Cu2MgCl.The latter reagent should be used when the group R is methyl.An interesting 1,3-diene formation is observed on treating excess of ethynyltrimethylsilane (Ib) with R3Cu2MgCl; this reaction involves addition of intermediary vinylcuprates to unreacted 1-alkynylsilane (Ib).The intermediary 1,3-dienyl adduct (VIIb) reacts with various electrophiles to give 1,3-dienes, RCH=C(SiMe3)CH=C(E)SiMe3 (VIIIb).
- Westmijze, H.,Kleijn, H.,Vermeer, P.
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p. 317 - 324
(2007/10/02)
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