- Photocatalytic Alkylation of Pyrroles and Indoles with α-Diazo Esters
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This article describes the photoalkylation of electron-rich aromatic compounds with diazo esters. C-2-alkylated indoles and pyrroles are obtained with good yields even though the photocatalyst loading is as low as 0.075 mol %. For EWG-substituted substrates, the addition of a catalytic amount of N,N-dimethyl-4-methoxyaniline is required. Both EWG-EWG- and EWG-EDG-substituted diazo esters are suitable as alkylating agents. The reaction selectivity and mechanistic experiments suggest that carbenes/carbenoid intermediates are not involved in the reaction pathway.
- Ciszewski, Lukasz W.,Durka, Jakub,Gryko, Dorota
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supporting information
p. 7028 - 7032
(2019/09/12)
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- The MOF-driven synthesis of supported palladium clusters with catalytic activity for carbene-mediated chemistry
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The development of catalysts able to assist industrially important chemical processes is a topic of high importance. In view of the catalytic capabilities of small metal clusters, research efforts are being focused on the synthesis of novel catalysts bearing such active sites. Here we report a heterogeneous catalyst consisting of Pd4 clusters with mixed-valence 0/+1 oxidation states, stabilized and homogeneously organized within the walls of a metal-organic framework (MOF). The resulting solid catalyst outperforms state-of-the-art metal catalysts in carbene-mediated reactions of diazoacetates, with high yields (>90%) and turnover numbers (up to 100,000). In addition, the MOF-supported Pd4 clusters retain their catalytic activity in repeated batch and flow reactions (>20 cycles). Our findings demonstrate how this synthetic approach may now instruct the future design of heterogeneous catalysts with advantageous reaction capabilities for other important processes.
- Fortea-Pérez, Francisco R.,Mon, Marta,Ferrando-Soria, Jesús,Boronat, Mercedes,Leyva-Pérez, Antonio,Corma, Avelino,Herrera, Juan Manuel,Osadchii, Dmitrii,Gascon, Jorge,Armentano, Donatella,Pardo, Emilio
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p. 760 - 766
(2017/07/04)
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- Preparation of a novel silica gel-adsorbed Br?nsted acid catalyst for the solvent-free esterification of bromoacetic acid with benzyl alcohol
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A new bifunctional Br?nsted acid catalyst that contains two sulfo groups was prepared. The adsorption of this new bifunctional Br?nsted acid catalyst on silica gel made it possible to be reused 10 times without a loss of catalytic activity in the solvent-free esterification of bromoacetic acid with an equiv. of benzyl alcohol without the formation of dibenzyl ether.
- Funabiki, Kazumasa,Komeda, Takuya,Sakaida, Yuta,Kubota, Yasuhiro,Matsui, Masaki
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p. 116 - 120
(2013/02/23)
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- Esterification in ionic liquids: The influence of solvent basicity
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(Chemical Equation Presented) The second-order rate constant (k 2) for the esterification of methoxyacetic acid with benzyl alcohol is reported in a range of ionic and molecular solvents. The solvent effects on esterification rate are examined by using a linear solvation energy relationship based on the Kamlet-Taft solvent scales (α, β, and π*). It is shown that the hydrogen bond basicity of the solvent is the dominant parameter in determining the esterification rate and that the best rates are achieved in low basicity solvents.
- Wells, Thomas P.,Hallett, Jason P.,Williams, Charlotte K.,Welton, Tom
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p. 5585 - 5588
(2008/12/20)
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- Improved ester interchange catalysts
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(equation presented) Mixed alkoxide/aryloxide clusters are long-lived and milder than previously reported ester interchange catalysts. They completely transform difficult substrates in a single synthetic operation with lower catalyst and reagent ester loadings. In addition to superior activities, these mixed clusters are kinetically less basic toward enolizable esters.
- Kissling, Rebecca M.,Gagne, Michel R.
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p. 4209 - 4212
(2007/10/03)
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