Catalytic Enantioselective Fluorination of ?-Cyano Esters by Phase-Transfer Catalysis Using Chiral Quaternary Ammonium Salts.
نویسندگان
چکیده
منابع مشابه
Catalytic enantioselective fluorination of beta-keto esters by phase-transfer catalysis using chiral quaternary ammonium salts.
[reaction: see text] The catalytic enantioselective electrophilic fluorination promoted by quaternary ammonium salt from cinchonine as a phase-transfer catalyst is described. Treatment of beta-keto esters with N-fluorobenzenesulfonimide as the fluorine source under mild reaction conditions afforded the corresponding alpha-fluoro beta-keto esters in exellent yields with good to moderate enantiom...
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We report a catalytic enantioselective electrophilic fluorination of alkenes to form tertiary and quaternary C(sp3)-F bonds and generate β-amino- and β-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, an...
متن کاملEnantioselective nucleophilic difluoromethylation of aromatic aldehydes with Me3SiCF2SO2Ph and PhSO2CF2H reagents catalyzed by chiral quaternary ammonium salts
BACKGROUND Although the nucleophilic difluoromethylation of aldehydes, ketones, and imines has been realized with PhSO(2)CF(2)H and related reagents, there are still no reports on the enantioselective nucleophilic reactions. RESULTS With a chiral quaternary ammonium salt as the catalyst and KOH as the base, we describe the first enantioselective difluoromethylation of aromatic aldehydes with ...
متن کاملDesign, synthesis, and application of tartaric acid derived N-spiro quaternary ammonium salts as chiral phase-transfer catalysts.
A novel class of tartaric acid-derived N-spiro quaternary ammonium salts was synthesised starting from known TADDOLs. These compounds were found to catalyse the asymmetric α-alkylation of glycine Schiff bases with high enantioselectivities and in good yields.
متن کاملAsymmetric electrophilic fluorination using an anionic chiral phase-transfer catalyst.
The discovery of distinct modes of asymmetric catalysis has the potential to rapidly advance chemists' ability to build enantioenriched molecules. As an example, the use of chiral cation salts as phase-transfer catalysts for anionic reagents has enabled a vast set of enantioselective transformations. Here, we present evidence that a largely overlooked analogous mechanism wherein a chiral anioni...
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ژورنال
عنوان ژورنال: ChemInform
سال: 2005
ISSN: 0931-7597,1522-2667
DOI: 10.1002/chin.200512093