- Electrocatalytic Reduction of C-C π-Bonds via a Cobaltocene-Derived Concerted Proton-Electron Transfer Mediator: Fumarate Hydrogenation as a Model Study
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Reductive concerted proton-electron transfer (CPET) is poorly developed for the reduction of C-C π-bonds, including for activated alkenes that can succumb to deleterious pathways (e.g., a competing hydrogen evolution reaction or oligomerization) in a standard electrochemical reduction. We demonstrate herein that selective hydrogenation of the C-C π-bond of fumarate esters can be achieved via electrocatalytic CPET (eCPET) using a CPET mediator comprising cobaltocene with a tethered Br?nsted base. High selectivity for electrocatalytic hydrogenation is observed only when the mediator is present. Mechanistic analysis sheds light on two distinct kinetic regimes based on the substrate concentration: low fumarate concentrations operate via rate-limiting CPET followed by an electron-transfer/proton-transfer (ET/PT) step, whereas high concentrations operate via CPET followed by a rate-limiting ET/PT step.
- Derosa, Joseph,Garrido-Barros, Pablo,Peters, Jonas C.
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supporting information
p. 9303 - 9307
(2021/07/19)
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- Zwitterion-Catalyzed Isomerization of Maleic to Fumaric Acid Diesters
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Fumaric acid diesters are important building blocks for organic synthesis. A class of zwitterionic organocatalysts based on an amide anion/iminium cation charge pair were found to be effective in catalyzing the isomerization of maleic acid diesters to give fumaric acid diesters. Comparison of the performance of different zwitterionic organocatalysts toward the reaction revealed that nonclassical hydrogen bonding was involved in the stabilization of the Michael adduct intermediate.
- Lam, Ying-Pong,Lam, Zachary,Yeung, Ying-Yeung
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p. 1183 - 1190
(2021/01/09)
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- Efficient synthesis of symmetrical phthalate and maleate diesters using phosphinite ionic liquids
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Symmetrical dialkyl phthalates and maleates were synthesized using phosphinite ionic liquid as a catalyst and reaction medium. The results indicated that phosphinite ionic liquid shows better catalytic and reusable performance without using any acid or base catalyst. Under the optimum conditions, using 1-methyl-3-(4-phosphinitebutyl) imidazolium chloride as catalyst, the conversion of phthalic and maleic anhydrides to the corresponding diesters of primary and secondary alcohols was occurred in 72-85% yields. The diesters of tertiary alcohols and phenols could not be prepared by this method. A kind of widely used plasticizer, dioctyl phthalate, was prepared in good yield under these conditions. The ionic liquid could be reused three times after easy separation from the products without any disposal. Iranian Chemical Society 2012.
- Valizadeh,Khalili
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p. 529 - 534
(2013/02/22)
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- Highly chemo- and stereoselective intermolecular coupling of diazoacetates to give cis-olefins by using Grubbs second-generation catalyst
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Highly stereoselective formation of cis-2-ene-1,4-diesters by homo- and heterocoupling of α-diazoacetates in the presence of Grubbs second-generation catalyst is demonstrated. The dual reactivity of the catalyst in alkene metathesis and diazocoupling has been exploited in the synthesis of 12-26-membered macrocyclic dienyl dilactones by one-pot carbene dimerisation/ring-closing metathesis.
- Hodgson, David M.,Angrish, Deepshikha
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p. 3470 - 3479
(2008/02/08)
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- Unsaturated mono-esters and their use in coating compositions
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Hydroxy functional, unsaturated diesters are disclosed that comprise the esterification reaction products of unsaturated anhydrides with secondary alcohols to form monoesters, followed by oxyalkylation of the monoester with epoxy compounds, whereby a diester is formed with hydroxy functionality. Use of secondary alcohol yields monoesters less prone to disproportionation. The unsaturated diesters may be copolymerized with vinyl monomers to form hydroxy functional copolymers useful in coating applications, wherein they may be included in compositions along with a curing agent that is reactive with hydroxy groups.
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- Liquid crystal control of bimolecular thermal reactions. Highly regioselective pericycloaddition of fumarates to 2,6-dialkoxyanthracenes in liquid-crystalline media
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The ability of liquid crystalline solvent phases to control the stereochemical course of bimolecular thermal reactions of 2,6-dialkoxyanthracenes with a series of fumarates conducted at 130-180°C has been examined, primarily with respect to the structural compatibility of the solutes with the solvent mesogens. For the case of the model thermal [4 + 2] cycloadditions of 2,6-bis(decyloxy)anthracene to bis(trans-4-cyclohexylcyclohexyl) and cholesteryl trans-4-cyclohexylcyclohexyl fumarates at 130-150°C, cholesteryl 2,4-dichlorobenzoate (CDCB) and bis(4-pentyloxyphenyl) trans-1,4-cyclohexanedicarboxylate (BPCD) serve well as cholesteric and smectic liquid crystalline solvents and result in the preferential formation of syn-isomers with an extremely high level of regioselection (syn/anti ≥ 20/1). In contrast, the isotropic solvents with closely related structures give isomer ratios of only ≥ 3/1. Structural similarities between the solutes and the solvent mesogens appear to play a key and influential role in controlling the stereochemical course of the reaction. The temperature dependence for the isomer distribution affords an estimate of the differences of solvation enthalpy and entropy between syn and anti transition states in the anisotropic media.
- Kansui,Hiraoka,Kunieda
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p. 5346 - 5352
(2007/10/03)
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- A Useful Synthesis of Chiral Glyoxylates
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A convenient synthesis of the cyclohexyl, (1R,3R,4S)-3-p-methyl and (1S-endo)-2-bornyl glyoxylates, from the respective alcohols and other very available materials, as a model applicable to that of other chiral, sensitive glyoxylates, is described.
- Fernandez, Franco,Garcia, Gerardo,Rodriguez, Jose E.
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p. 2837 - 2847
(2007/10/02)
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- Process for the preparation of fumaric acid monoesters
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Fumaric acid monoesters can be prepared by introducing a hydroxyl compound at a rate corresponding to the progress of the reaction into a solution or a melt of maleic anhydride, which may optionally be substituted, if appropriate in the presence of a cis-trans catalyst. New fumaric acid monoesters can be formed by the process.
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