20 research outputs found

    Enantioselective Synthesis of Fluoro‚ÄďDihydroquinazolones and ‚ąíBenzooxazinones by Fluorination-Initiated Asymmetric Cyclization Reactions

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    Stereoselective synthesis of two fluorine-bearing drug-like scaffolds, dihydroquinazolone and benzooxazinone, has been accomplished through asymmetric fluorocyclization reactions initiated by the fluorination process. The reaction employs double axially chiral anionic phase-transfer catalysts to achieve high diastereo- and enantioselectivities, and a wide range of fluorine-containing dihydroquinazolones were obtained (>20:1 dr, up to 98% ee)

    A combination of directing groups and chiral anion phase-transfer catalysis for enantioselective fluorination of alkenes

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    We report a catalytic enantioselective electrophilic fluorination of alkenes to form tertiary and quaternary C(sp3)-F bonds and generate ő≤-amino- and ő≤-aryl-allylic fluorides. The reaction takes advantage of the ability of chiral phosphate anions to serve as solid‚Äďliquid phase transfer catalysts and hydrogen bond with directing groups on the substrate. A variety of heterocyclic, carbocyclic, and acyclic alkenes react with good to excellent yields and high enantioselectivities. Further, we demonstrate a one-pot, tandem dihalogenation‚Äďcyclization reaction, using the same catalytic system twice in series, with an analogous electrophilic brominating reagent in the second step

    A combination of directing groups and chiral anion phase-transfer catalysis for enantioselective fluorination of alkenes.

    No full text
    We report a catalytic enantioselective electrophilic fluorination of alkenes to form tertiary and quaternary C(sp3)-F bonds and generate ő≤-amino- and ő≤-aryl-allylic fluorides. The reaction takes advantage of the ability of chiral phosphate anions to serve as solid-liquid phase transfer catalysts and hydrogen bond with directing groups on the substrate. A variety of heterocyclic, carbocyclic, and acyclic alkenes react with good to excellent yields and high enantioselectivities. Further, we demonstrate a one-pot, tandem dihalogenation-cyclization reaction, using the same catalytic system twice in series, with an analogous electrophilic brominating reagent in the second step

    Enantioselective Halocyclization Using Reagents Tailored for Chiral Anion Phase-Transfer Catalysis

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    A chiral anion phase-transfer system for enantioselective halogenation is described. Highly insoluble, ionic reagents were developed as electrophilic bromine and iodine sources, and application of this system to <i>o</i>-anilidostyrenes afforded halogenated 4<i>H</i>-3,1-benzoxazines with excellent yield and enantioselectivity

    Enantioselective Halocyclization Using Reagents Tailored for Chiral Anion Phase-Transfer Catalysis

    No full text
    A chiral anion phase-transfer system for enantioselective halogenation is described. Highly insoluble, ionic reagents were developed as electrophilic bromine and iodine sources, and application of this system to <i>o</i>-anilidostyrenes afforded halogenated 4<i>H</i>-3,1-benzoxazines with excellent yield and enantioselectivity

    Enantioselective Halocyclization Using Reagents Tailored for Chiral Anion Phase-Transfer Catalysis

    No full text
    A chiral anion phase-transfer system for enantioselective halogenation is described. Highly insoluble, ionic reagents were developed as electrophilic bromine and iodine sources, and application of this system to <i>o</i>-anilidostyrenes afforded halogenated 4<i>H</i>-3,1-benzoxazines with excellent yield and enantioselectivity
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