- Asymmetric synthesis of α-bromohydrins by carrot root as biocatalyst and conversion to enantiopure β-hydroxytriazoles and styrene oxides using click chemistry and SN2 ring-closure
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In this study we have combined the bioreduction of α-bromoketones using carrot root as biocatalyst and click chemistry for the preparation of enantiopure β-hydroxytriazoles in excellent enantiomeric excesses and yields. Moreover, we have utilized chiral α-halohydrins for the synthesis of enantiopure styrene oxides in very good yields and enantiomeric excesses. Structural assignments of the products were based on their 1H and 13C NMR data and their optical rotations. The enantiomeric excess of the chiral products was obtained by HPLC analysis.
- Hosseinzadeh, Rahman,Mohadjerani, Maryam,Mesgar, Sakineh
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p. 583 - 591
(2019/02/17)
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- Olefins oxidation with molecular O2 in the presence of chiral Mn (III) salen complex supported on magnetic CoFe2O4@SiO2@CPTMS
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In the present study, CoFe2O4@SiO2@CPTMS nanocomposite was synthesized and the homogeneous chiral Mn-salen complex was anchored covalently onto the surface of CoFe2O4@SiO2@CPTMS nanocomposite. The heterogeneous Mn-salen magnetic nanocatalyst (CoFe2O4@SiO2@CPTMS@ chiral Mn (III) Complex) was characterized by different techniques including transmission electron microscopy (TEM), Fourier transform infrared (FT-IR), vibrating sample magnetometer (VSM), scanning electron microscopy (SEM), powder X-ray diffraction (XRD) and thermogravimetric analysis (TGA). Then, the aerobic enantioselective oxidation of olefins to the corresponding epoxide was investigated in the presence of magnetic chiral CoFe2O4@SiO2@Mn (III) complex at ambient conditions within 90?min. The results showed the corresponding products were synthesized with excellent yields and selectivity. In addition, the heterogeneous CoFe2O4@SiO2@ CPTMS@ chiral Mn (III) complex has benefits such as high selectivity and comparable catalytic reactivity with its homogeneous analog as well as mild reaction condition, facile recovery, and recycling of the heterogeneous catalyst.
- Hemmat, Kaveh,Nasseri, Mohammad A.,Allahresani, Ali
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- Stereoselective epoxidation of alkenes with hydrogen peroxide using a bipyrrolidine-based family of manganese complexes
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Novel manganese complexes containing N4-tetradentate ligands derived from chiral bipyrrolidinediamines catalyze the stereoselective epoxidation of a wide array of alkenes using low catalyst loadings (0.1 mol%) and hydrogen peroxide (1.2 equiv.) as terminal oxidant. This family of catalysts affords good to excellent yields (80-100%) and moderate to good ees (40-73%) in short reaction times (30 min) making efficient use of hydrogen peroxide.
- Garcia-Bosch, Isaac,Gomez, Laura,Polo, Alfonso,Ribas, Xavi,Costas, Miquel
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supporting information; experimental part
p. 65 - 70
(2012/03/27)
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- Highly enantioselective ylide-mediated synthesis of terminal epoxides
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The highly efficient asymmetric epoxidation of aldehydes by methylene transfer is now possible using new sulfonium salts. This journal is
- Piccinini, Alessandro,Kavanagh, Sarah A.,Connon, Stephen J.
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supporting information; experimental part
p. 7814 - 7816
(2012/09/05)
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- Enantioselective synthesis of phenyl-ethanolamines through application of chiral sulfoxide
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Efficient enantioselective synthesis of (R)- and (S)-enantiomers of 2-(tert-butylamino)-1-(p-methoxyphenyl)-ethanol has been achieved in high enantiomeric excess by using asymmetric sulfoxide as a chiral auxiliary. The present synthetic approach was further extended to the asymmetric synthesis of (R)-salbutamol. Copyright Taylor & Francis Group, LLC.
- Sivakumar, Aathimanivelu V.,Lahoti, Anand M.,Bhat, Sujata V.
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p. 3338 - 3347
(2011/03/19)
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- Asymmetric epoxidation of styrenes catalyzed by molybdenum complexes with amino alcohol ligands
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Two common amino alcohols, prolinol and isolucinol, and their derivatives have been screened to coordinate with MoO2(acac)2 to form in situ catalysts for asymmetric epoxidation of styrenes with the highest enantioselectivity of 84% for 4-fluoro-styrene under the optimized reaction conditions.
- Wang, Yi,Wu, Zhiqing,Li, Zhengkai,Zhou, Xiang-Ge
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experimental part
p. 2509 - 2511
(2009/09/05)
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- A chiral iron-sexipyridine complex as a catalyst for alkene epoxidation with hydrogen peroxide
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A chiral iron-sexipyridine complex-hydrogen peroxide mixture is a highly efficient catalytic system for styrene epoxidation with excellent reactivity (3 min, 95% yield) and chemoselectivity (98%). The Royal Society of Chemistry.
- Yeung, Ho-Lun,Sham, Kiu-Chor,Tsang, Chui-Shan,Lau, Tai-Chu,Kwong, Hoi-Lun
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scheme or table
p. 3801 - 3803
(2009/02/08)
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- Chiral styrene oxides from α-haloacetophenones using NaBH4 and TarB-NO2, a chiral Lewis acid
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High enantioselectivities are obtained for the preparation of chiral styrene oxides through reduction of α-haloacetophenones using TarB-NO 2 reagent and the inexpensive and mild reducing agent NaBH 4. The epoxides are easily obtained in up to 95% ee through routine acid-base workup of the product alcohols. Either the (R) or (S) epoxide can be obtained by using the appropriate l- or d-tartaric acid starting material in the TarB-NO2 reagent.
- Cordes, David B.,Kwong, Tracey J.,Morgan, Kellie A.,Singaram, Bakthan
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p. 349 - 351
(2007/10/03)
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- Enantioselective allylic oxidation of cycloalkenes by using Cu(II)-tris(oxazoline) complex as a catalyst
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Optically active copper(II)-tris(oxazoline) complex that was synthesized as a model compound of the active site of non-heme oxygenase, was found to catalyze allylic oxidation of cycloalkenes to give the corresponding 2-cycloalkenyl benzoates with moderate to excellent enantioselectivity (up to 93% ee) under die Kharash-Sosnovsky reaction conditions.
- Kawasaki, Ken-Ichi,Katsuki, Tsutomu
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p. 6337 - 6350
(2007/10/03)
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