- A reusable, insoluble polymer-bound bis(oxazoline) (IPB-box) for highly enantioselective heterogeneous cyclopropanation reactions
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A reusable, insoluble polystyrene-supported bis(oxazoline) was developed, affording e.e.s > 90% in the heterogeneous enantioselective cyclopropanation of styrene and 1,1-disubstituted alkenes with ethyl diazoacetate.
- Mandoli, Alessandro,Orlandi, Simonetta,Fini, Dario,Salvadori, Piero
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- A chiral dimethyl cyclopropanecarboxylic preparation method of the formamide
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The invention discloses a preparation method of chiral dimethyl cyclopropyl carboxamide. The method comprises a step of asymmetric cyclopropyl alkylation and a step of catalytic amidation of cyclopropyl formic ether, wherein in the step of asymmetric cyclopropyl alkylation, a cyclopropyl alkylation reaction is carried out on ethyl diazoacetate and isobutene under the catalysis of a chiral ligand complex of a cuprous salt so as to obtain (S)-dimethyl cyclopropyl formate; and in the step of catalytic amidation of cyclopropyl formic ether, an ammonolysis reaction is carried out on the (S)-dimethyl cyclopropyl formate by one step so as to directly obtain (S)-2,2-dimethyl cyclopropyl carboxamide, and refining the carboxamide with an alcohol so as to obtain the chiral dimethyl cyclopropyl carboxamide with chemical purity being greater than 99.5% and an e.e. value being greater than 99.5%. Thus, the method used for synthesizing the (S)-2,2-dimethyl cyclopropyl carboxamide is environment-friendly, simple, rapid and efficient.
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Paragraph 0025; 0037; 0041; 0045; 0049; 0053; 0054; 0055
(2018/11/03)
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- Siliceous mesocellular foam-supported aza(bisoxazoline)-copper catalysts
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Aza(bisoxazoline) was easily immobilized on siliceous mesocellular foam (MCF) in a systematic approach. It was found that silanol precapping, linker group flexibility, ligand loading, and silanol postcapping were important factors to consider in optimizing silica-supported aza(bisoxazoline) catalysts. The optimized MCF-supported aza(bisoxazoline)-copper catalyst offered the same enantioselectivity as its homogeneous counterpart, and excellent recyclability. The heterogenized catalyst showed a much higher chemoselectivity in a short reaction time. The heterogenized aza(bisoxazoline)-copper(I) catalyst was successfully applied to a circulating flow-type packed bed reactor with excellent productivity and enantioselectivity. The circulating flow-type reactor was found to be very useful for gas-generating catalytic reactions such as cyclopropanation reaction.
- Lim, Jaehong,Riduan, Siti Nurhanna,Su, Seong Lee,Ying, Jackie Y.
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p. 1295 - 1308
(2009/06/05)
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- Improved enantioselectivity of immobilized chiral bisoxazolines by partial precapping of the siliceous mesocellular foam support with trimethylsilyl groups
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Siliceous mesocellular foams (MCF) were partially surface-modified with trimethylsilyl (TMS) groups prior to the immobilization of chiral tert-butylbisoxazolines. The resulting MCF-supported bisoxazoline-Cu(I) catalyst showed superior enantioselectivity (
- Lee, Su Seong,Hadinoto, Sukandar,Ying, Jackie Y.
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p. 1248 - 1254
(2007/10/03)
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