- An Anionic, Chelating C(sp3)/NHC ligand from the Combination of an N-heterobicyclic Carbene and Barbituric Heterocycle
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The coordination chemistry of the anionic NHC1-based on an imidazo[1,5-a]pyridin-3-ylidene (IPy) platform substituted at the C5 position by an anionic barbituric heterocycle was studied with d6(Ru(II), Mn(I)) and d8(Pd(II), Rh(I), Ir(I), Au(III)) transition-metal centers. While the anionic barbituric heterocycle is planar in the zwitterionic NHC precursor 1·H, NMR spectroscopic analyses supplemented by X-ray diffraction studies evidenced the chelating behavior of ligand 1-through the carbenic and the malonic carbon atoms in all of the complexes, resulting from a deformation of the lateral barbituric heterocycle. The complexes were obtained by reaction of the free carbene with the appropriate metal precursor, except for the Au(III) complex 10, which was obtained by oxidation of the antecedent gold(I) complex [AuCl(1)]?with PhICl2as an external oxidant. During the course of the process, the kinetic gold(I) intermediate 9 resulting from the oxidation of the malonic carbon of the barbituric moiety was isolated upon crystallization from the reaction mixture. The νCOstretching frequencies recorded for complex [Rh(1)(CO)2] (5) demonstrated the strong donating character of the malonate-C(sp3)/NHC ligand 1-. The ruthenium complex [Ru(1)Cl(p-cymene)] (11) was implemented as a precatalyst in the dehydrogenative synthesis of carboxylic acid derivatives from primary alcohols and exhibited high activities at low catalyst loadings (25-250 ppm) and a large tolerance toward functional groups.
- Benaissa, Idir,Gajda, Katarzyna,Vendier, Laure,Lugan, No?l,Kajetanowicz, Anna,Grela, Karol,Michelet, Véronique,César, Vincent,Bastin, Stéphanie
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p. 3223 - 3234
(2021/09/30)
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- Industrial preparation method of low-cost 2,5-furan dicarboxylic acid
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The invention provides a preparation method of low-cost 2,5-furan dicarboxylic acid. The preparation method comprises the step of reacting furan formate, molten salt and a catalyst under the conditionof carbon dioxide gas to obtain the 2,5-furan dicarboxylic acid; a melting point of the molten salt is less than or equal to 400 DEG C; the catalyst comprises a metal salt catalyst and/or an organicalkali catalyst. The preparation method provided by the invention has the benefits that the 2,5-furan dicarboxylic acid is prepared by taking the furan formate as an initial raw material and the cheapand easy-to-obtain conventional metal salt as the catalyst and by specially utilizing a monomer or a mixture of organic salt or inorganic salt; both the used catalyst and the used molten salt are cheap chemical products, so that the reaction cost is greatly reduced; the preparation method is simple in process, low in reaction temperature, economic, environmentally-friendly and suitable for large-scale industrial production and pushes the industrialization progress of the 2,5-furan dicarboxylic acid.
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Paragraph 0076; 0077-0081; 0083; 0089; 0092; 0095; 0098
(2018/10/19)
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- Decarboxylative cross-coupling of aryl tosylates with aromatic carboxylate salts
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(Figure Presented) A bimetallic copper/palladium catalyst system is disclosed that enables the use of tosylates as carbon electrophiles in decarboxylative coupling reactions. A variety of aromatic carboxylate salts, regardless of their substitution pattern, have been coupled with these inexpensive and readily available electrophiles to give the corresponding biaryl compounds in good yields (see scheme).
- Goossen, Luksa J.,Rodriguez, Nuria,Lange, Paul P.,Linder, Christophe
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supporting information; experimental part
p. 1111 - 1114
(2010/04/29)
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- Biaryl and aryl ketone synthesis via Pd-catalyzed decarboxylase coupling of carboxylate salts with aryl triflates
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A bimetallic catalyst system has been developed that for the first time allows the decarboxylative crosscoupling of aryl and acyl carboxylates with aryl triflates. In contrast to aryl halides, these electrophiles give rise to non-coordinating anions as byproducts, which do not interfere with the decarboxylation step that leads to the generation of the carbon nucleophilic crosscoupling partner. As a result, the scope of carboxylate substrates usable in this transformation was extended from ortho-substituted or otherwise activated derivatives to a broad range of ortho-, meta-, and para-substituted aromatic carboxylates. Two alternative protocols have been optimized, one involving heating the substrates in the presence of CuI/1,10- phenanthroline (10-15 mol %) and PdI2/phosphine (23 mol%) in NMP for 1-24 h, the other involving CuI/l,10-phenanthroline (615mol%) and PdBr2/Tol-BINAP (2 mol % ) in NMP using microwave heating for 5-10 min. While most products are accessible using standard heating, the use of microwave irradiation was found to be beneficial especially for the conversion of non-activated carboxylates with functionalized aryl triflates. The synthetic utility of the transformation is demonstrated with 48 examples showing the scope and limitations of both protocols. In mechanistic studies, the special role of microwave irradiation is elucidated, and further perspectives of decarboxylase crosscouplings are discussed.
- Goossen, Lukas J.,Linder, Christophe,Rodriguez, Nuria,Lange, Paul P.
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supporting information; experimental part
p. 9336 - 9349
(2010/04/03)
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- Synthesis of biaryls and aryl ketones via microwave-assisted decarboxylative cross-couplings
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A protocol for the microwave-assisted decarboxylative cross-couplings of carboxylic acid salts with aryl halides has been developed that allows the synthesis of various biaryls and aryl ketones in high yields. After careful adaptation of the bimetallic ca
- Goossen, Lukas J.,Linder, Bettina Zimmermanns Christophe,Rodriguez, Nuria,Lange, Paul P.,Hartung, Jens
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experimental part
p. 2667 - 2674
(2009/12/31)
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- Decarboxylative biaryl synthesis from aromatic carboxylates and aryl triflates
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A new catalyst system, generated in situ from Cu2O, 1,10-phenanthroline, PdI2, and Tol-BINAP, for the first time allows the decarboxylative coupling of carboxylic acids with aryl triflates. In contrast to previous decarboxylative couplings that remained limited to certain activated carboxylates, e.g., ortho-substituted benzoates, this halide-free protocol is generally applicable to aromatic carboxylic acid salts regardless of their substitution pattern. Copyright
- Goossen, Lukas J.,Rodriguez, Nuria,Linder, Christophe
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supporting information; experimental part
p. 15248 - 15249
(2009/03/11)
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- Preparation of anhydrous organic acid salts
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One-step process for preparing anhydrous, organic acid alkali or alkaline earth metal salts by contacting and reacting an organic or polymeric acid fluoride, anhydride or ester and an organic alkali or alkaline earth metal silanolate.
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