Enantioselective fluorination of β-keto ester using a PEG-bound urea-containing chiral quaternary ammonium salt catalyst
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...
متن کاملSyntheses and Applications of (Thio)Urea-Containing Chiral Quaternary Ammonium Salt Catalysts
We herein report our efforts to obtain a new class of systematically modified bifunctional (thio)urea-containing quaternary ammonium salts based on easily obtainable chiral backbones. Among the different classes of catalysts that were successfully synthesized, those based on trans-1,2-cyclohexane diamine were found to be the most powerful for the asymmetric α-fluorination of β-keto esters. Sele...
متن کاملDesign of chiral urea-quaternary ammonium salt hybrid catalysts for asymmetric reactions of glycine Schiff bases.
Bifunctional chiral urea-containing quaternary ammonium salts can be straightforwardly synthesised in good yield and with high structural diversity via a scalable and operationally simple highly telescoped sequence starting from trans-1,2-cyclohexanediamine. These novel hybrid catalysts were systematically investigated for their potential to control glycine Schiff bases in asymmetric addition r...
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The distribution behavior of ofloxacin enantiomers was examined in the aqueous and organic solvent of a two-phase system containing chiral selector L-tartarate. The effect of extraction equilibrium time, buffer pH, organic solvents and length of alkyl chain of L-tartarate on the partition coefficients and enantioselectivity of racemic ofloxacin were investigated, respectively. The L-tartara...
متن کاملEnantioselective chlorination and fluorination of beta-keto phosphonates catalyzed by chiral Lewis acids.
The direct chiral Lewis acidic enantioselective chlorination and fluorination of beta-keto phosphonates is presented; the chlorination proceeds in high yields and with up to 94% ee using NCS as the chloro source, while the fluorination with (PhSO2)2NF (NFSI) gives the optically active alpha-fluoro-beta-keto phosphonates in moderate to good yields and with up to 91% ee.
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ژورنال
عنوان ژورنال: Arkivoc
سال: 2016
ISSN: 1551-7012
DOI: 10.3998/ark.5550190.p009.420