- An uncommon use of irradiated flavins: Br?nsted acid catalysis
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We present that thioacetalization of aldehydes can be induced by blue light irradiation in the presence of a catalytic amount of riboflavin tetraacetate (RFTA) under aerobic conditions. Several control experiments have suggested that the reaction is more
- Arakawa, Yukihiro,Mihara, Tomohiro,Fujii, Hiroki,Minagawa, Keiji,Imada, Yasushi
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supporting information
p. 5661 - 5664
(2020/06/09)
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- Chemoselective catalysis with organosoluble lewis acidic polyoxotungstates
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The preparation of new organosoluble Lewis acidic polyoxometalates (POMs) is reported. These complexes were prepared by the incorporation of Zr, Sc, and Y atoms into the corresponding monolacunary Dawson [P2W 17O61]10- and Keggin [PW11O 39]7- polyoxotungstates. The catalytic activity of these compounds was evaluated for C-C bond formation in the DielsAlder, Mannich, and Mukaiyama-type reactions. Comparisons with previously described Lewis acidic POMs are reported. Competitive reactions between imines and aldehydes or between various imines demonstrated that fine tuning of the reactivity could be reached by varying the metal atom in-corporated into the polyanionic framework. A series of experiments that employed pyridine derivatives allowed us to distinguish between the Lewis and induced Bronsted acidity of the POMs. These catalysts activate imines in a Lewis acidic way, whereas aldehydes are activated by indirect Bronsted catalysis.
- Dupre, Nathalie,Remy, Pauline,Micoine, Kevin,Boglio, Cecile,Thorimbert, Serge,Lacote, Emmanuel,Hasenknopf, Bernold,Malacria, Max
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supporting information; experimental part
p. 7256 - 7264
(2010/09/04)
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- Polymer fibers as carriers for homogeneous catalysts
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This paper describes a polymer fiber-based approach for the immobilization of homogeneous catalysts. The goal is to generate products that are free of catalysts which would be of great importance for the development of optoelectronic or pharmaceutical compounds. Electrospinning was employed to prepare the non-woven fiber assembly composed of polystyrene. The homogeneous catalyst scandium triflate was immobilized on the polystyrene fibers during electrospinning and on corresponding core shell fibers using a fiber template approach. An imino aldol and an aza-Diels-Alder model reaction were carried out with each fibrous catalytic system. This resulted in the immobilization of homogeneous catalysts in a polymer environment without loss of their catalytic activity and may even be enhanced when compared with reactions carried out in homogeneous solutions.
- Stasiak, Michael,Studer, Armido,Greiner, Andreas,Wendorff, Joachim H.
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p. 6150 - 6156
(2008/02/13)
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- An efficient and mild bismuth triflate-catalysed three-component Mannich-type reaction
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In the presence of a catalytic amount of Bi(OTf)3·4H 2O, aldehydes together with amines react with silyl enolates to afford the corresponding Mannich-type adducts smoothly. A wide variety of silyl enolates derived from ketones, as well as esters and thioesters, react rapidly to afford the β-amino ketones or the β-amino esters in high yields (up to 94%). The Royal Society of Chemistry.
- Ollevier, Thierry,Nadeau, Etienne
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p. 3126 - 3134
(2008/04/01)
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- Increased lewis acidity in hafnium-substituted polyoxotungstates
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Monolacunary polyoxotungs-tates [α1-P2W 17O61]10 and [α-PW11O 39]10 react with HfGl4 to yield [α1-HfP2W17O61]su
- Boglio, Cecile,Micoine, Kevin,Remy, Pauline,Hasenknopf, Bernold,Thorimbert, Serge,Lacote, Emmanuel,Malacria, Max,Afonso, Carlos,Tabet, Jean-Claude
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p. 5426 - 5432
(2008/02/09)
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- Lanthanide complexes of the monovacant Dawson polyoxotungstate [α1-P2W17O61]10- as selective and recoverable Lewis acid catalysts
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(Chemical Equation Presented) Catalytic cornerstone: Lanthanide(III) complexes of a lacunary Dawson-type polyoxometalate catalyze Lewis acid mediated reactions (see figure, TMS = trimethylsilyl). The compounds (NBu 4)5H2[α
- Boglio, Cecile,Lemiere, Gilles,Hasenknopf, Bernold,Thorimbert, Serge,Lacote, Emmanuel,Malacria, Max
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p. 3324 - 3327
(2008/02/11)
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- Mannich-type reactions in a colloidal solution formed by sodium tetrakis(3,5-trifluoromethylphenyl)borate as a catalyst in water
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Sodium tetrakis(3,5-trifluoromethylphenyl)borate [NaBAr4F] efficiently catalyzed the one-pot, three-component Mannich reaction of ketones with aromatic aldehydes and different anilines in water at an ambient temperature and afforded the corresponding β-amino carbonyl compounds in good to excellent yields.
- Chang, Chi-Tsing,Liao, Bei-Sih,Liu, Shiuh-Tzung
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p. 9257 - 9259
(2008/02/10)
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- Mannich-type reaction catalyzed by dicyanoketene ethylene acetal and the related polymer-supported π-acid: Aldimine-selective reactions in the coexistence of aldehydes
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Mannich-type reaction of aldimines and enolsilyl ethers proceeded with excellent aldimine-selectivity in the coexistence of aldehydes by means of dicyanoketene ethylene acetal (DCKEA) and the related polymer-supported dicyanoketene acetal as a recyclable π -acid catalyst.
- Tanaka, Nobuyuki,Masaki, Yukio
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p. 406 - 408
(2007/10/03)
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- A novel classification of Lewis acids on the basis of activity and selectivity
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Group 3-15 metal chlorides (Lewis acids) were classified on the basis of activity and aldehyde- and aldimine-selectivity in an addition reaction of a silyl enol ether. Based on the experimental results, metal chlorides (Lewis acids) were classified as fol
- Kobayashi, Shu,Busujima, Tsuyoshi,Nagayama, Satoshi
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p. 3491 - 3494
(2007/10/03)
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- HBF4 catalyzed Mannich-type reaction in aqueous media
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HBF4 catalyzed Mannich-type reaction took place smoothly in aqueous media to afford β-amino carbonyl compounds in high yields. One-pot synthesis of β-amino carbonyl compounds from aldehyde and amine also worked well.
- Akiyama, Takahiko,Takaya, Jun,Kagoshima, Hirotaka
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p. 1045 - 1048
(2007/10/03)
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- Chemoselective activation of aldimine in preference to aldehyde by the combination of BF3?OEt2 and water: Novel catalyst for the mannich-type reaction
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Reported herein are that catalytic amount of conventional Lewis acids activated aldimines in preference to aldehydes, and addition of water to BF3?OEt2 accelerated the Mannich-type reaction significantly to afford β-amino carbonyl compounds in high yields.
- Akiyama, Takahiko,Takaya, Jun,Kagoshima, Hirotaka
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p. 947 - 948
(2007/10/03)
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- One-pot Mannich-type reaction in water: HBF4 catalyzed condensation of aldehydes, amines, and silyl enolates for the synthesis of β-amino carbonyl compounds
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HBF4 catalyzed Mannich-type reactions of aldehydes, amines, and silyl enolates took place smoothly in water in the presence of a surfactant to afford β-amino carbonyl compounds in high yields. Thieme Stuttgart.
- Akiyama, Takahiko
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p. 1426 - 1428
(2007/10/03)
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- Gallium enolate-mediated intermolecular aldol reaction and addition reaction of α-bromoketone with imine
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Treatment of α-bromoketone with gallium triiodide or methyl galliumiodide prepared in situ provides gallium enolates which react with carbonyl compounds or imines to give β - hydroxy ketones or β -phenylamino ketones effectively in moderate yields.
- Han, Ying,Huang, Yao-Zeng
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p. 7751 - 7754
(2007/10/03)
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- The Polymer Effect on Catalysts. Aldimine-Selective Reactions in the Coexistence of Aldehydes Using a Polymer-Supported Scandium Catalyst
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Aldimine-selective reactions in the coexistence of aldehydes using a polymer-supported scandium catalyst have been developed. These are remarkable examples of the polymer effect on catalysts to increase selectivities, which can be explained by the stabili
- Kobayashi, Shu,Nagayama, Satoshi
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p. 653 - 654
(2007/10/03)
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- Group 4 Metal Triflates as Efficient Catalysts for Allylations of Imines with Allyltributylstannane and Mannich-Type Reactions of Imines with Silyl Enol Ethers
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Catalytic allylation of imines with allyltributylstannane and catalytic Mannich-type reactions of imines with silyl enol ethers were successfully carried out in the presence of a group 4 metal triflate, such as Zr(OTf)4 or Hf(OTf)4, to afford the correspo
- Kobayashi, Shu,Iwamoto, Shunsuke,Nagayama, Satoshi
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p. 1099 - 1101
(2007/10/03)
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- Polymer scandium-catalyzed three-component reactions leading to diverse amino ketone, amino ester, and amino nitrile derivatives
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In the presence of a polymer-supported scandium catalyst (PA-Sc-TAD), three-component reactions between aldeheydes, amines, and silylated nucleophiles proceeded smoothly to afford β-amino ketones, β-amino esters, and α-amino nitriles in high yields. These
- Kobayashi, Shu,Nagayama, Satoshi,Busujima, Tsuyoshi
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p. 9221 - 9224
(2007/10/03)
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