Heterogeneous asymmetric Henry reaction using a chiral bis(oxazoline)-copper complex immobilized on magnetically separable mesocellular mesoporous silica support

Lee, Jun-Mun; Kim, Jaeyun; Shin, Young June; Yeom, Chang-Eun; Lee, Ji Eun; Hyeon, Taeghwan; Kim, B. Moon

doi:10.1016/j.tetasy.2010.01.024

Cited by 51 publications

(29 citation statements)

References 43 publications

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“…Cy5.5 azide was purchased from Lumiprobe (Hallandale Beach, FL). 6-Azidohexanoic acid (AHA) was synthesized by us following a reported method 13 with slight modifications. Methoxypolyethylene glycol azide (mPEG-azide) was synthesized from mPEG 750 gmol −1 14 .…”

Section: Methodsmentioning

confidence: 99%

Synthesis of Water-Soluble Camptothecin–Polyoxetane Conjugates via Click Chemistry

et al. 2012

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Water soluble camptothecin (CPT)-polyoxetane conjugates were synthesized using a clickable polymeric platform P(EAMO) that was made by polymerization of acetylene-functionalized 3-ethyl-3-hydroxymethyl oxetane (i.e., EAMO). CPT was first modified with a linker 6-azidohexanoic acid via an ester linkage to yield CPT-azide. CPT-azide was then click coupled to P(EAMO) in dichloromethane using bromotris(triphenylphosphine) copper(I)/N,N-diisopropylethylamine. For water solubility and cytocompatibility improvement, methoxypolyethylene glycol azide (mPEG-azide) was synthesized from mPEG 750 gmol−1 and click grafted using copper(II) sulfate and sodium ascorbate to P(EAMO)-g-CPT. 1H NMR spectroscopy confirmed synthesis of all intermediates and the final product P(EAMO)-g-CPT/PEG. CPT was found to retain its therapeutically active lactone form. The resulting P(EAMO)-g-CPT/PEG conjugates were water soluble and produced dose-dependent cytotoxicity to human glioma cells and increased γ-H2AX foci formation, indicating extensive cell cycle-dependent DNA damage. Altogether, we have synthesized CPT-polymer conjugates able to induce controlled toxicity to human cancer cells.

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Section: Methodsmentioning

confidence: 99%

Synthesis of Water-Soluble Camptothecin–Polyoxetane Conjugates via Click Chemistry

et al. 2012

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“…Lee et al designed and synthesized heterogeneous catalysts containing an IndaBOX ligand by immobilizing the ligand onto hierarchically ordered magnetic active mesocellular mesoporous silica (M-HMMS) via click chemistry (Figure 7.9). 64 Using the resulting material as a heterogeneous catalyst, the authors examined the asymmetric Henry reactions between various aldehydes and nitromethane. The best stereoselectivity (86.0% ee) was obtained when the reaction was carried out with the catalyst whose free silanol groups were precapped by trimethylsilane (TMS).…”

Section: Asymmetric Henry Reactionmentioning

confidence: 99%

Nanostructured Catalysts for the Aldol, Knoevenagel, and Henry Reactions

Asefa

Biradar

Das

et al. 2013

Nanocatalysis Synthesis and Applications

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“…Examples described in the literature utilizing ordered mesoporous materials are relatively uncommon but they exist for the covalent immobilization of complexes on different materials, such as mesocellular foam silicas [11][12][13][14][15], MCM41 and MCM48 [16], hierarchically-ordered mesocellular mesoporous silica [17], SBA15 and HMS [18,19], and a periodic mesoporous phenylene-silica [20]. To date, a few examples are described using noncovalent methods of immobilization, such as the hydrogen bonding of ion-tagged bis(oxazoline) ligands on SBA15 [21] and electrostatic interactions with Al-MCM41…”

Section: Introductionmentioning

confidence: 99%

Improved methodology for non-covalent immobilization of tert-butyl-azabis(oxazoline)–copper complex on Al-MCM41

Feldman

Fraile

2015

Applied Catalysis A: General

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Please cite this article as: Robert A.Feldman, José M.Fraile, Improved methodology for non-covalent immobilization of tert-butyl-azabis(oxazoline)-copper complex on Al-MCM41, Applied Catalysis A, General http://dx. Highlights-Chiral azabox-copper complex was immobilized on Al-MCM41 in a non-covalent way.-Cu(OTf) 2 was first impregnated by incipient wetness and then treated at 450ºC.-Final modification with azabox leads to stable immobilized complexes.-Better results in enantioselective cyclopropanation are obtained at high temperature. AbstractCopper sites are supported on Al-MCM41 by thermally treating copper(II) triflate that was deposited using the incipient wetness method. The change of the chemical state of the triflate anions following thermal treatment is monitored using TGA and SEM-EDX.Thermal treatment yields copper sites that then can be modified with chiral tert-butylazabis(oxazoline) by adding a solution of this ligand to the support using incipient wetness. The catalyst produced in this way is efficient and stable with good enantioselectivity, and can be used in the cyclopropanation of styrene with ethyl diazoacetate under conditions employing an elevated temperature. The use of thermal treatment in the catalyst preparation method produces catalysts that are superior to the solids prepared by cation exchange or incipient wetness of the pre-formed complex.

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Heterogeneous asymmetric Henry reaction using a chiral bis(oxazoline)-copper complex immobilized on magnetically separable mesocellular mesoporous silica support

Cited by 51 publications

References 43 publications

Synthesis of Water-Soluble Camptothecin–Polyoxetane Conjugates via Click Chemistry

Synthesis of Water-Soluble Camptothecin–Polyoxetane Conjugates via Click Chemistry

Nanostructured Catalysts for the Aldol, Knoevenagel, and Henry Reactions

Improved methodology for non-covalent immobilization of tert-butyl-azabis(oxazoline)–copper complex on Al-MCM41

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