22847-18-3Relevant articles and documents
Imidazolium Based Fluorous N-Heterocyclic Carbenes as Effective and Recyclable Organocatalysts for Redox Esterification
?ervenková ??astná, Lucie,Bílková, Veronika,Cézová, Tereza,Cu?ínová, Petra,Karban, Jind?ich,?ermák, Jan,Krupková, Alena,Stra?ák, Tomá?
, p. 3591 - 3598 (2020/06/17)
A series of new highly fluorophilic ionic liquids (f > 110) was synthetized from 3-iodopropyltris(3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl)silane and N-alkyl imidazoles, followed by anion exchange. N-heterocyclic carbenes generated in situ from obtained imidazolium salts were employed to catalyze redox esterification (umpolung) of cinnamaldehyde with alcohols. The most effective N-methyl derivative with iodide as a counter anion was studied in detail with respect to the optimization of reaction conditions, substrate scope and recyclability. Recovery of the precatalyst was achieved using either fluorous extraction or performing the reaction in suitable fluorous biphase system with direct recycling of the fluorinated precatalyst phase. For both tested options, the catalytic activity did not significantly decrease within 5 subsequent cycles. The redox esterification was shown to proceed also in supercritical carbon dioxide (scCO2) as an alternative solvent where the activity of the fluorinated catalyst was also superior to the nonfluorinated model, while retaining the benefit of easy recycling.
Ionic liquid catalytic synthesis of styrene-acrylic acid ester derivative of the method (by machine translation)
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Paragraph 0031, (2019/05/08)
The invention provides an ionic liquid catalytic synthesis of styrene-acrylic acid ester derivative of the method, the method adopts the imidazole ionic liquid as catalyst, in order to cinnamic aldehyde or its derivatives and nandrolone or testosterone alcohol or phenol derivatives as raw materials, without any additional acid and alkali, one-step reaction, to obtain the styrene-acrylic acid ester derivative. Compared with the prior art, the maximum of this invention is characterized in that the raw materials are all simple and easy to obtain, security and stability of the compound, the reaction time is short, after the reaction by simple extraction, concentration or crystallization can be obtained pure product, at the same time can also be realized in the use of the recycling of the catalyst, catalyst recycled is very convenient and almost no "wastes" problem. The invention it has less catalyst levels, the reaction selectivity is high, and the yield is high, the operation is simple, pollution is small, green high degree of several advantages; in the setting under the reaction conditions, the conversion of raw materials and the yield of the product are as high as 90% or more. (by machine translation)
Catalytic, Enantioselective β-Protonation through a Cooperative Activation Strategy
Wang, Michael H.,Barsoum, David,Schwamb, C. Benjamin,Cohen, Daniel T.,Goess, Brian C.,Riedrich, Matthias,Chan, Audrey,Maki, Brooks E.,Mishra, Rama K.,Scheidt, Karl A.
, p. 4689 - 4702 (2017/05/12)
The NHC-catalyzed transformation of unsaturated aldehydes into saturated esters through an organocatalytic homoenolate process has been thoroughly studied. Leveraging a unique “Umpolung”-mediated β-protonation, this process has evolved from a test bed for homoenolate reactivity to a broader platform for asymmetric catalysis. Inspired by our success in using the β-protonation process to generate enals from ynals with good E/Z selectivity, our early studies found that an asymmetric variation of this reaction was not only feasible, but also adaptable to a kinetic resolution of secondary alcohols through NHC-catalyzed acylation. In-depth analysis of this process determined that careful catalyst and solvent pairing is critical for optimal yield and selectivity; proper choice of nonpolar solvent provided improved yield through suppression of an oxidative side reaction, while employment of a cooperative catalytic approach through inclusion of a hydrogen bond donor cocatalyst significantly improved enantioselectivity.
