• Bulletin of the Korean Chemical Society
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• v.31 no.10
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• pp.2973-2979
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• 2010

The newly synthesized homogeneous chiral Co(III) salen complexes were anchored non-covalently on the acidic sites of mesoporous Al-SBA-15. The Bronsted and Lewis acidic sites are attributed to the immobilization of fluorine functionalized chiral salen complexes on the supports. XRD, BET, TEM, FT-IR and ESCA (XPS) analyses were performed to characterize the property of support, and the structure of new homogeneous and heterogeneous chiral Co salen catalyst. The homogeneous and heterogeneous catalysts could be applied in asymmetric ring opening of epichlorohydrine (ECH) by water. They showed very high enantioselectivity and a good yield up to 99% in the catalytic synthesis of optically active products.

• Applied Chemistry for Engineering
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• v.26 no.2
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• pp.132-137
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• 2015

BEA-zeolite was modified by alkaline solution to introduce mesoporosity in the crystals and the homogeneous chiral Co(III) salen was immobilized in the mesopores. The dinuclear chiral Co(salen)-$GaCl_3$ catalyst immobilized on mesoporous BEA-zeolite showed high activity for the regioselective ring opening of terminal epoxides by carboxylic acids. Various chiral monoester derivatives could be synthesized with moderate enantioselectivity (47~69 ee%) from racemic epoxides through above reaction. When the chiral (S)-ECH was used as a reactant, it was efficiently resolved by carboxylic acid with a high enantioselectivity in the presence of heterogenized chiral salen catalyst, and the ring opened product afforded optically pure monoester epoxide (R)-GB (up to 98 ee%) through the ring closing in the basic solution by elimination of HCl. The heterogeneous catalyst could be fabricated easily, and the catalytic activity was retained for several times reuse without any further regeneration step.

• Applied Chemistry for Engineering
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• v.18 no.6
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• pp.630-635
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• 2007

New chiral Co-salen complexes with one $C_3-^tBu$ group in the structure have been synthesized and applied as a chiral catalyst. A dimeric chiral salen having aluminum group metal salts such as $AlCl_3$ displayed very high catalytic reactivity and enantioselectivity for the asymmetric ring opening of epoxides to synthesize optically pure ${\alpha}$-aryloxy alcohols via phenolic kinetic resolution. The salen complexes immobilized on the inorganic support were also used as effective catalysts in that reaction. The identity of metal salts in the new chiral salen complex has proved to be important in the enantioselective reactions.

• Applied Chemistry for Engineering
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• v.18 no.4
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• pp.330-336
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• 2007

In this study, new dinuclear chiral Co (salen) complexes bearing $BF_3$ have been synthesized and their properties as the asymmetric catalyst have been examined. The NMR, UV and ESCA analyses were performed to determine the structure of synthesized catalysts. Their catalytic activity and selectivity have been demonstrated for the asymmetric ring opening of various terminal epoxides by hydrolytic kinetic resolution technology. The easily prepared dimeric complexes exhibited very high enantioselectivity for the asymmetric ring opening of epoxides with $H_2O$ nucleophile, providing enantiomerically enriched terminal epoxides (> 99 %ee). The dimeric structured chiral salen showed remakablely enhanced reactivity and may be employed substantially lower loadings than its monomeric analogues, and in addition no racemization happened during the separation of product epoxides. The system described in this work is very efficient for the sinthesis of chiral epoxide and 1,2-diol intermediates.

• Bulletin of the Korean Chemical Society
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• v.29 no.10
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• pp.1879-1880
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• 2008

• Applied Chemistry for Engineering
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• v.18 no.3
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• pp.218-226
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• 2007

The stereoselective synthesis of chiral terminal epoxides is of immense academic and industrial interest due to their utility as versatile starting materials as well as chiral intermediates. In this study, new dinuclear chiral Co (salen) complexes bearing gallium-, indium- and tallium-chloride have been synthesized and characterized. The mass and EXAFS spectra provided the direct evidence of formation of dinuclear complex. Their catalytic activity and selectivity have been demonstrated for the asymmetric ring opening of various terminal epoxides having ether or ester groups by hydrolytic kinetic resolution technology. The easily prepared dimeric complexes exhibited very high enantioselectivity for the asymmetric ring opening of epoxides with $H_2O$ nucleophile, providing enantiomerically enriched terminal epoxides (> 99% ee). The dimeric structured chiral salen showed remarkably enhanced reactivity and may be employed substantially lower loadings than its monomeric analogues. The system described in this work is very efficient for the synthesis of chiral epoxide and 1,2-diol intermediates

• Korean Chemical Engineering Research
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• v.46 no.4
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• pp.769-776
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• 2008

The stereoselective synthesis of chiral terminal epoxide is of immense interest due to their utility as versatile starting materials as well as chiral intermediates. In this study, new chiral Co(salen) complexes bearing cobalt(II) chloride, iron(III) chloride and zinc(II) nitrate have been synthesized and characterized. The mass and EXAFS spectra provided the direct evidence of formation of complex. Their catalytic activity and selectivity have been demonstrated for the asymmetric ring opening of terminal epoxides such as styrene oxide and phenylglycidylether by hydrolytic kinetic resolution technology and for the synthesis of glycidyl buthylate. The easily prepared complexes exhibited very high enantioselectivity for the asymmetric ring opening of epoxides with $H_2O$ nucleophile, providing enantiomerically enriched terminal epoxides (>99% ee). The newly synthesized chiral salen showed remakablely enhanced reactivity with substantially low loadings. The system described in this work is very efficient for the sinthesis of chiral epoxide and 1,2-diol intermediates.

• Korean Chemical Engineering Research
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• v.43 no.6
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• pp.647-661
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• 2005

The stereoselective synthesis of chiral terminal epoxide is of immense academic and industrial interest due to their utility as versatile starting materials as well as chiral intermediates. In this review, we investigate the research and development trend in the asymmetric ring opening reactions using cobalt salen catalysts. Hydrolytic kinetic resolution (HKR) technology is the very prominent way to prepare optically pure terminal epoxides among available methods. We have synthesized homogeneous and heterogeneous chiral dinuclear salen complexes and demonstrated their catalytic activity and selectivity for the asymmetric ring opening of terminal epoxides with variety of nucleophiles and for asymmetric cyclization to prepare optically pure terminal epoxides in one step. The resolved ring opened product combined with ring closing in the presence of base and catalyst afforded the enantioriched terminal epoxides in quantitaive yield. Potentially, these catalysts are using on an industrial scale to produce chiral intermediates. The experimental results of HKR technology applied to the synthesis of various chiral compounds are presented in this paper.

• Applied Chemistry for Engineering
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• v.18 no.6
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• pp.562-567
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• 2007

The stereoselective synthesis of chiral terminal epoxide is of immense academic and industrial interest due to their use as versatile starting materials as well as chiral intermediates. In this study, new polymeric chiral Co(salen) complexes bearing tallium (III)chloride and iron (III)chloride (ferric chloride) have been synthesized and characterized. Their catalytic activity and selectivity have been demonstrated for the asymmetric ring opening of various terminal epoxides using water and phenol derivatives as nucleophiles. The easily prepared polymeric complexes exhibited very high enantioselectivity for the asymmetric ring opening of epoxides with $H_2O$ and phenol nucleophiles, providing enantiomerically enriched terminal epoxides (> 98% ee). The system described in this work is very efficient for the synthesis of chiral epoxide, 1,2-diol and ${\alpha}$-aryloxy alcohol intermediates.

• Applied Chemistry for Engineering
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• v.27 no.5
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• pp.490-494
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• 2016

This paper describes the very efficient and highly enantioselective ring opening of terminal epoxides with alkyl and arene sulfonic acid. The dinuclear chiral (salen) Co complexes bearing Lewis acids of Al, Ga and In catalyze the reaction enantioselectively in the presence of tetrabutylammonium chloride using tert-butyl methyl ether as a solvent. The variation of the anion of the tetra butyl ammonium salt has significant impact on the reactivity and selectivity of the asymmetric ring opening of phenyl glycidyl ether with p-toluenesulfonic acid. The order of reactivity and selectivity was found to be $Cl^-$ > $l^-$ > $Br^-$ > $OH^-$. Strong synergistic effects of the different Lewis acid centers of Co-Al, Co-Ga and Co-In complexes were observed in the catalytic process. The dinuclear chiral salen catalyst containing $AlCl_3$ was found to be most active and highly enantioselective (91% ee).