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    Sequential Double α-Arylation of N-Allylureas by Asymmetric Deprotonation and N→C Aryl Migration
    Organic Letters (2010)
    Daniel J. TetlowUlrich HenneckeJames RafteryMichael J. WaringDavid S. ClarkeJonathan Clayden
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    Abstract:
    On lithiation with lithium amides, N-allyl-N′-aryl ureas undergo rearrangement with transfer of the aryl ring from N to the allylic α carbon. From the α-arylated products, a further aryl transfer under the influence of a chiral lithium amide allows the enantioselective construction of 1,1-diarylallylamine derivatives. Stereoselectivity in these reactions results from the enantioselective formation of a planar chiral allyllithium under kinetic control.
    Keywords:
    Lithium amide
    Amide
    Topics:
    Coordination Chemistry and Organometallics
    Asymmetric Synthesis and Catalysis
    Asymmetric Hydrogenation and Catalysis
    Transition metal ion induced deprotonation of amide hydrogens in sulfhydryl containing compounds
    Journal of Inorganic and Nuclear Chemistry (1981)
    Imre SóvágóRobert B. Martin
    Amide
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    A Novel Highly Effective Chiral Lithium Amide for Catalytic Enantioselective Deprotonation of meso-Epoxides
    Tetrahedron Letters (1997)
    Masatoshi AsamiTakashi SugaKiyoshi HondaSeiichi Inoue
    Lithium amide
    Lithium diisopropylamide
    Amide
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    Effect of lithium salts on enantioselective deprotonation of cyclic ketones
    Tetrahedron Letters (1995)
    Marek MajewskiRyszard ŁaźnyPaweł Nowak
    Lithium amide
    Amide
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    Chiral base-mediated rearrangement of meso-cyclohexene oxides to allylic alcohols
    Tetrahedron Letters (1996)
    Peter O’BrienPierre Poumellec
    Lithium amide
    Cyclohexenone
    Diastereomer
    Allylic alcohol
    Cyclohexene oxide
    Amide
    Base (topology)
    Citations (29)
    Allylsilanes in organic synthesis; Stereoselective hydroxylactonisation of chiral amide-allylsilanes
    Tetrahedron Letters (1987)
    Andrew T. RussellGarry Procter
    Amide
    Citations (34)
    Enantioselective deprotonation of two racemic cyclic carbonyl compounds by a chiral lithium amide
    Tetrahedron Letters (1986)
    M. B. ELEVELDH. Hogeveen
    Lithium amide
    Amide
    Citations (52)
    Effect of Lithium Salts on Enantioselective Deprotonation of Cyclic Ketones
    Tetrahedron Letters (1995)
    Marek Majewski
    Lithium amide
    Amide
    Citations (36)
    Catalytic enantioselective deprotonation of meso-epoxides by the use of chiral lithium amide
    Tetrahedron Asymmetry (1994)
    Masatoshi AsamiT. IshizakiSeiichi Inoue
    Lithium amide
    Lithium diisopropylamide
    Amide
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    Optimisation of a lithium magnesiate for use in the non-cryogenic asymmetric deprotonation of prochiral ketones
    Dalton Transactions (2013)
    Javier FrancosSilvia Zaragoza-CaleroCharles T. O’Hara
    A study has been conducted to determine whether lithium magnesiates are feasible candidates for the enantioselective deprotonation of 4-alkylcyclohexanones. The commercially available chiral amine (+)-bis[(R)-1-phenylethyl]amine (2-H) was utilised to induce enantioselection. When transformed to its lithium salt and combined with nBu2Mg, improved enantioselective deprotonation of 4-tert-butylcyclohexanone (with respect to the monometallic lithium amide) at 20 °C was observed. In an attempt to optimise the reaction further, different additives were added to the lithium amide. The best performing deprotonations at 0 °C were those in which (Me3SiCH2)2Mg (er pro-S 74 : 26) and (Me3SiCH2)2Mn (er pro-S 72 : 28) were added, hence the lithium magnesiate "LiMg(2)(CH2SiMe3)2" was used in the remainder of the study. The optimum solvent for the reaction was found to be THF. NMR spectroscopic studies of a D8-THF solution of "LiMg(2)(CH2SiMe3)2" appear to show that this mono-amide bis-alkyl species is in equilibrium with a bis-amide mono-alkyl compound (and a tris-alkyl lithium magnesiate). When a genuine bis-amide lithium magnesiate solution is used, the deprotonation results were essentially identical to those obtained for "LiMg(2)(CH2SiMe3)2". By adding LiCl to "LiMg(2)(CH2SiMe3)2" the er at 0 °C improved to 81 : 19. At −78 °C good yields and an er of 93 : 7 were obtained. This LiCl-containing base was used to successfully deprotonate other 4-alkylcyclohexanones.
    Lithium amide
    Amide
    Citations (6)
    Oxovanadium(IV)-Promoted Peptide-Amide Deprotonation in Aqueous Solution
    Inorganic Chemistry (1998)
    Tivadar KissK. PetrohánPéter BuglyóDaniele SannaGiovanni Micera
    The speciation and solution structural studies of the complexes formed in the aqueous solution of oxovanadium(IV) and 2-hydroxyhippuric acid (a pseudopeptide, SalGly) revealed that the metal ion-promoted deprotonation and coordination of the peptide-amide occurs at pH as low as 4 and the complex formed is the predominant species at physiological pH.
    Amide
    Genetic algorithm
    Citations (25)