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1.
In the presence of base, 3-subslituted 4-fonnyl- and 4-acetylsydnones decarbonylated to afford the corresponding 3-substituted sydnones. The Claisen-Schmidt reaction occurred between 3-substituted 4-for-mylsydnones and methyl ketone (such as 4-acetylsydnones, acetone and acetophenone) in dilute basic solution or electrogenerated basic (EGB) solution. 相似文献
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Dr. Bao‐Hua Xu Raul Alfonso Adler Yanez Hiroshi Nakatsuka Prof. Dr. Masato Kitamura Dr. Gerald Kehr Prof. Dr. Gerhard Erker 《化学:亚洲杂志》2012,7(6):1347-1356
The frustrated Lewis pair (FLP) Mes2PCH2CH2B(C6F5)2 ( 1 ) reacts with an enolizable conjugated ynone by 1,4‐addition involving enolate tautomerization to give an eight‐membered zwitterionic heterocycle. The conjugated endione PhCO‐CH?CH‐COPh reacts with the intermolecular FLP tBu3P/B(C6F5)3 by a simple 1,4‐addition to an enone subunit. The same substrate undergoes a more complex reaction with the FLP 1 that involves internal acetal formation to give a heterobicyclic zwitterionic product. FLP 1 reacts with dimethyl maleate by selective overall addition to the C?C double bond to give a six‐membered heterocycle. It adds analogously to the triple bond of an acetylenic ester to give a similarly structured six‐membered heterocycle. The intermolecular FLP P(o‐tolyl)3/B(C6F5)3 reacts analogously with acetylenic ester by trans‐addition to the carbon–carbon triple bond. An excess of the intermolecular FLP tBu3P/B(C6F5)3, which contains a more nucleophilic phosphane, reacts differently with acetylenic ester examples, namely by O? C(alkyl) bond cleavage to give the {R‐CO2[B(C6F5)3]2?}[alkyl‐PtBu3+] salts. Simple aryl or alkyl esters react analogously by using the borane‐stabilized carboxylates as good leaving groups. All essential products were characterized by X‐ray diffraction. 相似文献
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Christian Fischer Prof. Dr. Christof Sparr 《Angewandte Chemie (International ed. in English)》2018,57(9):2436-2440
Despite the manifold use of heterocyclic fluorophores, only a fraction of the desired dye diversity can be accessed by contemporary synthetic approaches. Herein, we describe a modular method that converts various carboxylic acid esters directly into a broad spectrum of heteroanthrylium fluorophores. The double addition of heteroatom‐bridged 1,5‐bifunctional organomagnesium reagents to esters leads to the formation of acridinium, xanthylium, and SiR fluorophores after dehydrative acidic work‐up. This one‐step synthetic method provides access to organophotoredox catalysts for dual catalysis with nickel and dyes amenable to fluorescence enhancement. 相似文献
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Francesco Trotta Davide Cantamessa Marco Zanetti 《Journal of inclusion phenomena and macrocyclic chemistry》2000,37(1-4):83-92
Cyclodextrins act as inverse phase transfer catalystsin the oxidation of methyl ketones by hypochloride(the haloform reaction). The reaction is affected by thechoice and the amount of cyclodextrin. The reactionproceeds under mild reaction conditions and itprovides only the corresponding carboxylic acid asreaction product. No organic solvent is required. 相似文献
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Te-Butyl Telluroesters and Se-Butyl Selenoesters are hydrolyzed to carboxylic acids under very mild conditions by reaction with copper(II) chloride dihydrate. When the reaction is performed in ethanol or methanol, using anhydrous copper(II) chloride a transesterification occurred leading to the oxygenated esters in good yield. 相似文献
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Mohammad H. Mosslemin Mohammad Anary-Abbassinejad Alireza Hassanabadi Marzieh Mohebat Mohammad R. Nateghi 《合成通讯》2013,43(19):3482-3492
The reactive diionic intermediate generated by the addition of triphenylphosphine to electron-deficient acetylenic esters or ketones was trapped by mercaptoesters such as mercaptothioglycolate or methyl 3-mercaptopropanoate to produce substituted furans, vinyl sulfides, or dithioesters. 相似文献
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Kashparova V. P. Shubina E. N. Il’chibaeva I. B. Kashparov I. I. Zhukova I. Yu. Kagan E. Sh. 《Russian Journal of Electrochemistry》2020,56(5):422-425
Russian Journal of Electrochemistry - The conversion of alcohols into nitriles was studied under conditions of indirect electrochemical oxidation with a catalytic system... 相似文献
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A stereospecific synthesis of enones 3 by coupling reaction of α-acetoxy alkyl methyl vinyl ketones 2 and Gilman or Grignard reagents in the presence of a catalytic amount of copper (I) salt at low temperature, is described. 相似文献
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Lanqing Li Prof. Wei Gao Min Lei Prof. Dan Wen 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(42):10966-10972
Post treatment of metal-organic frameworks (MOFs) is widely employed to develop efficient electrocatalysts with better catalytic properties. But the complex processes of post treatment generally led to the collapse of the original structures of MOFs, making the preservation of their pristine hierarchical porous structure a great challenge. Herein, we propose the strategy of alkali treatment of Ni-MOF to transform it into Ni(OH)2 with similar morphology and enhanced electrocatalytic properties for methanol oxidation reaction (MOR). The structure and electrocatalytic properties of as-obtained Ni(OH)2 nanostructured flowers were seriously depended on the alkali concentrations. As the result, Ni(OH)2 obtained from Ni-MOF treated by 0.25 M NaOH (noted as Ni(OH)2-0.25) performs 1.5 and 2.5 times larger current density than those of Ni(OH)2-0.025 and Ni(OH)2-0.5 for MOR. Moreover, the electrocatalytic process and mechanism of MOR on the catalyst of Ni(OH)2-0.25 are also revealed. Hence, this ex situ conversion strategy of alkali treatment for Ni-MOF uncovered the transformation of MOFs in alkaline solution and develops robust electrocatalyst for practical application of methanol fuel cells. 相似文献
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Kseniya Revunova Dr. Georgii I. Nikonov 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(3):839-845
Simple bases (KOtBu, KOH) catalyze the silane‐promoted reduction of ketones and esters to alcohols and of aldimines to amines. The inexpensive silane PMHS (polymethylhydrosiloxane) can be used as the reducing reagent. Double and triple bonds, as well as nitro‐ and cyano‐groups are tolerated. Careful dosing of the silane allows for chemoselective reduction of a more reactive group in the presence of a less reactive group (for example, aldehyde reduction in the presence of ketone/ketone reduction in the presence of ester group). Mechanistic studies showed that addition of base to silanes leads to silicate species, which are the acting reducing agents. Under basic conditions, hydrosiloxanes (tetramethyldisiloxane, TMDS; PMHS) convert into simple silanes (H2SiMe2, H3SiMe), making this a practical method to generate these challenging silanes. 相似文献
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A mild transformation of various amides and imides into the corresponding esters and diesters in good yields by using chlorotrimethylsilane and alcohols at rt are described. Either primary, secondary, or tertiary amide or imide can be used in this transformation. Primary and secondary alcohols gave better yields than tertiary alcohols. 相似文献
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V. V. Chapurkin A. O. Litinskii A. V. Baklanov O. S. Leont’eva 《Russian Journal of General Chemistry》2005,75(2):290-293
Reaction of dialkyl esters of perfluoroadipic and perfluoropimelic acids with ketones form diketo esters. The possibility of cyclization of the products is discussed.__________Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 2, 2005, pp. 318–321.Original Russian Text Copyright © 2005 by Chapurkin, Litinskii, Baklanov, Leont’eva. 相似文献
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Fangyuan Zhou Lesong Li Kao Lin Feng Zhang Prof. Dr. Guo-Jun Deng Dr. Hang Gong 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(19):4246-4250
The radical–radical coupling reaction is an important synthetic strategy. In this study, the iron-catalyzed radical–radical cross-coupling reaction based on the decarboxylation of keto acids and decarbonylation of aliphatic aldehydes to obtain valuable aryl ketones is reported for the first time. Remarkably, when tertiary aldehydes were used as carbonyl sources, ketone esters were selectively obtained instead of ketones. The gram-scale preparation of aryl ketone through this strategy was easily achieved by using only 3 mol % of the iron catalyst. As a proof-of-concept, the bioactive molecule flurprimidol was synthesized in two steps by using this strategy. 相似文献
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Hans-Ulrich Gonzenbach Inga-Mai Tegmo-Larsson Jean-Pierre Grosclaude Kurt Schaffner 《Helvetica chimica acta》1977,60(3):1091-1123
2-Cyclopentenyl and 3-phenyl-2-cyclopentenyl methyl ketones (15–18, 30, 31) undergo a 1,3-acetyl shift on direct irradiation, and the oxa-di-π-methane rearrangement to photochemically non-interconverting endo and exo bicyclo-[2.1.0]pentyl methyl ketones on triplet sensitization. Exceptions include the 2-methyl-3-phenyl-2-cyclopentenyl methyl ketone 32 and the 1-phenyl-2-cyclo-pentenyl methyl ketone 44 which are unreactive on direct irradiation and on triplet sensitization, respectively, and the 2-phenyl-2-cyclopentenyl methyl ketones 42 and 43 which do not react under either condition. The reactive triplet of the 3-phenyl-2-cyclopentenyl methyl ketone 30 has been identified as the localized styrene π,π*-state of ET=59 kcal/mol by comparison of its phosphorescence at 77K in rigid glasses with that of 1-phenyl-cyclopentene, and by the independence of the quantum yield on sensitizer energy in the range of 61–74 kcal/mol. 相似文献