First example of a silica gel-supported optically active Mn(III)–salen complex as a heterogeneous asymmetric catalyst in the epoxidation of olefins

Pini, Dario; Mandoli, Alessandro; Orlandi, Simonetta; Salvadori, Piero

doi:10.1016/s0957-4166(99)00426-7

Cited by 80 publications

(44 citation statements)

References 14 publications

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“…Consequently, the immobilized catalysts display reduced enantioselectivity and lower efficiency in catalysis in comparison with their homogeneous counterparts. As a typical example, the immobilized salen-Mn system of Pini et al shows only up to 58% ee in epoxydation, which is much lower than that for Jacobsen-Katsuki salen complexes [66,69] . Another major problem is that the bonds between metals and ligands, even if covalent, are often broken under the harsh catalytic reaction conditions and the catalyst breaks away from the solid support and dissolves.…”

Section: Introductionmentioning

confidence: 93%

Chiral Metal-Organic Porous Materials: Synthetic Strategies and Applications in Chiral Separation and Catalysis

Kim

Banerjee

Yoon

et al. 2009

Topics in Current Chemistry

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In the light of growing demand for chiral purity in biological and chemical processes, the synthesis of chiral metal-organic porous materials (CMOPMs) have become immensely important because of their potential applications in chiral separation and asymmetric catalysis. In this chapter, the synthetic strategies for CMOPMs are discussed briefly keeping the focus on their applications. Two distinct approaches have been taken to synthesize a wide variety of chiral structures with different topologies and accessible cavities. Several CMOPMs have shown catalytic activity and enantioselectivity toward a number of chemical transformations. On many occasions, the chiral pores of the MOPMs have been utilized in order to achieve separation of enantiomers from racemates. Recent applications of homochiral MOPMs in heterogeneous asymmetric catalysis and chiral separations are also presented here.

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Section: Introductionmentioning

confidence: 93%

Chiral Metal-Organic Porous Materials: Synthetic Strategies and Applications in Chiral Separation and Catalysis

Kim

Banerjee

Yoon

et al. 2009

Topics in Current Chemistry

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“…However, the microscopic spaces in the zeolite pores are useless and restricted for the immobilization of large optically active salen molecules as mean of supports. Many types of heterogeneous salen catalysts have been developed by grafting on the inorganic material [15,16] or by copolymerization on the polymer [17,18] and by encapsulation in the pores [20,21]. The mesoporous material is an attractive support for heterogeneous catalysis application [1,10,15].…”

Section: Applmentioning

confidence: 99%

“…Various strategies have been explored to increase the catalytic efficiency of heterogenized salen catalysts. Some approaches were demonstrated successfully to date in the asymmetric catalysis by adopting the methodologies of adsorption, covalent bonding, as well as ship-in-bottle for immobilization of salen complexes [11][12][13][14][15][16][17][18][19].…”

Section: Introduction 1)mentioning

confidence: 99%

Synthesis of Optically Active Monoesters via Kinetic Resolution by Chiral Co (Salen) Complex Immobilized on Mesoporous BEA

Choi¹,

Park²,

Lee³

et al. 2015

Applied Chemistry for Engineering

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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)-GaCl3 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.

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“…This might be a reason for the well-known fact that the catalyst is deactivated after a few turnovers. For this reason, immobilization of a salen-Mn catalyst [45][46][47][48][49][50] has been considered as a proper alternative to enhance the catalyst stability since it leads to a lower local concentration of the catalyst and at the same time restricts complex mobility (site isolation). [47,51] In other words, dimerization and catalyst deactivation are expected to be suppressed by anchoring the MnA C H T U N G T R E N N U N G (III)-salen moieties to a carrier.…”

Section: Introductionmentioning

confidence: 99%

Continuous Application of Polyglycerol‐Supported Salen in a Membrane Reactor: Asymmetric Epoxidation of 6‐Cyano‐2,2‐dimethylchromene

Beigi¹,

Haag²,

Liese³

2008

Adv Synth Catal

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In the current work, suitability of hyperbranched polyglycerol as a high loading catalyst support is demonstrated. A polyglycerol-supported manganese-salen complex (chemzyme) is applied as a homogeneous catalyst in the epoxidation of 6-cyano-2,2-dimethylchromene. The recyclability of the corresponding catalyst was investigated in repetitive batch experiments as well as a continuous operation of the reaction in an ultrafiltration membrane reactor. An enhanced stability of the catalyst in repetitive batches was observed as a result of immobilization whereby the total turnover number increased from 23 in a single batch to 80 in four repetitive batches. To enable continuous operation, a continuously operated, stirred tanked reactor (CSTR) was equipped with an ultrafiltration membrane (MPF-50) and a retention of 98% was determined. The continuous chemzyme membrane reactor was operated over the course of 20 residence times. After approximately 12 residence times, the steady state was reached yielding 70% conversion as well as an enantiomeric excess up to 92%. A space-time yield (sty) of 458 g L À1 d À1 and a turnover frequency (TOF reaction ) of up to 18 h À1 was reached in the steady state. It was determined that the total turnover number (TTN) was enhanced by a factor of 10 from 24 (batch) up to 240 for 20 residence times in CSTR operation.

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First example of a silica gel-supported optically active Mn(III)–salen complex as a heterogeneous asymmetric catalyst in the epoxidation of olefins

Cited by 80 publications

References 14 publications

Chiral Metal-Organic Porous Materials: Synthetic Strategies and Applications in Chiral Separation and Catalysis

Chiral Metal-Organic Porous Materials: Synthetic Strategies and Applications in Chiral Separation and Catalysis

Synthesis of Optically Active Monoesters via Kinetic Resolution by Chiral Co (Salen) Complex Immobilized on Mesoporous BEA

Continuous Application of Polyglycerol‐Supported Salen in a Membrane Reactor: Asymmetric Epoxidation of 6‐Cyano‐2,2‐dimethylchromene

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