- Uncatalyzed conjugate addition of organozinc halides to enones in DME: A combined experimental/computational study on the role of the solvent and the reaction mechanism
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Both aryl and alkylzinc halides prepared by direct insertion of zinc into organic halides in the presence of LiCl underwent the conjugate addition reaction to nonenolizable unsaturated ketones in excellent yield, provided that DME was used instead of THF as the solvent. Diffusion NMR measurements highlighted that the species undergo considerable aggregation under the experimental conditions used in the synthetic procedure, but no substantial differences have been found between the two solvents. Density functional theory calculations, prompted by the experimental aggregation study, revealed an unexpected reaction mechanism, where the coordinating capabilities of DME stabilize a transition state involving two organozinc moieties, lowering the activation energy of the reaction with respect to that seen for THF, enough to explain the fast and quantitative reactions observed experimentally and the different behaviors of the two solvents.
- Casotti, Gianluca,Ciancaleoni, Gianluca,Lipparini, Filippo,Nieri, Chiara,Iuliano, Anna
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- Solvent-dependent behavior of arylvinylketones in HUSY-zeolite: a green alternative to liquid superacid medium
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Depending on the reaction conditions, arylvinylketones can be directly and efficiently converted using zeolites to indanones by cyclization or to dihydrochalcones through regioselective aryl addition or chemoselective hydride transfer.
- Sani Souna Sido, Abdelkarim,Chassaing, Stefan,Kumarraja, Mayilvasagam,Pale, Patrick,Sommer, Jean
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- Conjugate additions of α,β-unsaturated ketones with arylzinc species that form in situ from diethylzinc and arylboronic acids
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Conjugate addition of α,β-unsaturated ketones with arylzinc species that form in situ from diethylzinc and a series of arylboronic acids by boron-zinc exchange reactions were investigated. 1,4-Addition products were formed in yields of 34-93%.
- Dong, Lin,Xu, Yan-Jun,Gong, Liu-Zhu,Mi, Ai-Qiao,Jiang, Yao-Zhong
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- Enantioselective Conjugate Addition of Stabilized Arylzinc Iodide to Enones: an Improved Protocol of the Hayashi Reaction
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Stabilised arylzinc iodide, prepared by direct insertion of zinc into aryl iodides, were used as nucleophiles in the Hayashi Rh-catalysed enantioselective conjugate addition to enones. The reaction conditions were optimized in the addition of phenylzinc i
- Casotti, Gianluca,Rositano, Vincenzo,Iuliano, Anna
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p. 1126 - 1131
(2020/12/17)
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- An Atom-Economical Route to Substituted β-Arylethyl Ketones: Phosphomolybdic Acid-Catalyzed Carbohydroxylation of Terminal Alkynes in Organic Carbonate
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A highly efficient and atom-economical route for the synthesis of substituted β-arylethyl ketones was developed by using cheap phosphomolybdic acid (H3PMo12O40) as catalyst and non-volatile propylene carbonate (PC) as green solvent via the carbohydroxylation of terminal alkynes with benzylic alcohols under mild conditions. Various functional groups on the benzylic alcohols and terminal alkynes were tolerated, giving the corresponding substituted β-arylethyl ketones as products in good to excellent yields (up to 95%). It is worth noting that a turnover number (TON) of up to 520 was achieved in the protocol. The mechanism investigation showed that PC might stabilize the heteropoly anion and the carbocation intermediate thus facilitating the carbohydroxylation reaction. (Figure presented.).
- Yang, Guo-Ping,Zhang, Nan,Ma, Nuan-Nuan,Yu, Bing,Hu, Chang-Wen
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p. 926 - 932
(2017/03/27)
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- Ligand-free nickel-catalysed 1,4-addition of arylboronic acids to α,β-unsaturated carbonyl compounds
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A simple and efficient ligand-free nickel-based catalytic system has been developed for the 1,4-addition of arylboronic acids to α,β-unsaturated carbonyl compounds. With catalyst loadings of 1-2 mol%, a series of 1,4-adducts from chalcones and cinnamates was obtained in moderate to excellent yields within 5-30 min under a nitrogen atmosphere and microwave irradiation. The 1,4-addition of arylboronic acids to acrylates is less efficient.
- Chen, Wen,Sun, Lu,Huang, Xi,Wang, Jiayi,Peng, Yanqing,Song, Gonghua
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p. 1474 - 1482
(2015/05/19)
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- Decarboxylative substitution of β-keto acids to benzylic alcohols catalyzed by molecular iodine
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An efficient method for molecular iodine catalyzed decarboxylative substitution of β-keto acids with benzylic alcohols under mild conditions has been described and valuable α-functionalized ketones were obtained in good to excellent yields.
- Han, Fuzhong,Zhang, Xinxin,Hu, Minggang,Jia, Lina
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p. 11466 - 11471
(2015/12/04)
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- Synthesis of Substituted Aryl Ketones by Addition of Alcohols to Alkynes Using Amberlyst-15/Ionic Liquid as a Recyclable Catalytic System
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A highly efficient protocol for the synthesis of substituted aryl ketones by using Amberlyst-15 immobilized in [Bmim][PF6] ionic liquid has been firstly developed. The present protocol works under metal-free, solvent-free, mild reaction conditions with 100% atom efficiency. The various aryl ketones were obtained in good to excellent yields. The developed catalytic system was recycled efficiently up to five cycles without significant loss in catalytic activity.
- Wagh, Kishor V.,Bhanage, Bhalchandra M.
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supporting information
p. 759 - 764
(2015/03/30)
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- Catalytic decarboxylative alkylation of β-keto acids with sulfonamides via the cleavage of carbon-nitrogen and carbon-carbon bonds
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An efficient decarboxylative alkylation reaction of β-keto acids with N-benzylic or N-allylic sulfonamides has been developed, for the first time, through sequential cleavage of carbon-nitrogen and carbon-carbon bonds in the presence of 10 mol% of FeCl3.
- Yang, Cui-Feng,Wang, Jian-Yong,Tian, Shi-Kai
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supporting information; experimental part
p. 8343 - 8345
(2011/09/16)
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- Direct functionalization of benzylic C-Hs with vinyl acetates via Fe-catalysis
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Direct cross-coupling to construct sp3 C-sp3 C bonds via Fe-catalyzed benzylic C-H activation with 1-aryl vinyl acetate was developed.
- Song, Chun-Xiao,Cai, Gui-Xin,Farrell, Thomas R.,Jiang, Zhong-Ping,Li, Hu,Gan, Liang-Bing,Shi, Zhang-Jie
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supporting information; experimental part
p. 6002 - 6004
(2010/11/16)
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- Iron(III)-catalyzed addition of benzylic alcohols to aryl alkynes - A new synthesis of substituted aryl ketones
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A new, efficient and direct addition of benzylic alcohols with terminal aryl alkynes was developed with the inexpensive, non-toxic, FeCl3 catalyst in nitromethane. The reaction provides a simple method for the synthesis of substituted aryl ketones under mild conditions, and the reaction is highly atom-economical. Several substituted terminal alkynes underwent smooth reaction with various substituted benzylic alcohols. The electron-rich alkynes reacted more efficiently and gave higher yields than did the neutral or electron-deficient alkynes. A wide range of functional groups were tolerated in the developed protocol. The intermediate of this reaction was isolated, and a possible mechanism has been proposed. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
- Jana, Umasish,Biswas, Srijit,Maiti, Sukhendu
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experimental part
p. 5798 - 5804
(2009/06/08)
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- Superacid-Catalyzed Reactions of Cinnamic Acids and the Role of Superelectrophiles
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The chemistry of cinnamic acids and related compounds has been studied. In superacid-catalyzed reactions with arenes, two competing reaction mechanisms are proposed. Both mechanisms involve the formation of dicationic intermediates (superelectrophiles), and the reactions can lead to either chalcone-type products or indanone products. The direct observation of a dicationic species (by low-temperature 13C NMR) is reported. We provide clear evidence that protonated carboxylic acid groups (or the corresponding acyl cation) can enhance the reactivity of an adjacent electrophilic center. Triflic acid is also found to be an effective acid catalyst for the direct synthesis of some electron-deficient chalcones and heterocyclic chalcones from cinnnamic acids.
- Rendy, Rendy,Zhang, Yun,McElrea, Aaron,Gomez, Alma,Klumpp, Douglas A.
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p. 2340 - 2347
(2007/10/03)
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