- One-pot synthesis of 2-alkyl cycloketones on bifunctional Pd/ZrO2 catalyst
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2-Alkyl cycloketones are essential chemicals and intermediates for synthetic perfumes and pesticides, which are conventionally produced by multistep process including aldol condensation, separation and hydrogenation. In present work, a batch one-pot cascade approach using aldehydes and cycloketones as the raw materials, and a bifunctional Pd/ZrO2 catalyst was developed for the synthesis of 2-alkyl cycloketones, e.g., cyclohexanone and cycloheptanone. Very high aldehydes (except for paraldehyde with large steric hindrance) conversion and high yields for 2-alkyl cycloketones (e.g., 99 % of conversion for n-butanal and 76 wt.% of yield for 2-butyl cyclohexanone) were obtained at mild temperature of 140 °C. After 10 cycles of reuse, Pd/ZrO2 catalyst showed slight deactivation (ca. 5 % conversion and 10 % yield losses), due to the coke on the catalyst. However, the performance of the catalyst was completely recovered after an oxidative regeneration.
- Xue, Weiyang,Gu, Bin,Wu, Huiling,Liu, Mengyang,He, Songbo,Li, Jingmei,Rong, Xin,Sun, Chenglin
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- p-Toluenesulfonic acid catalysed fluorination of α-branched ketones for the construction of fluorinated quaternary carbon centres
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A p-toluenesulfonic acid catalyzed fluorination of α-branched ketones for the construction of fluorinated quaternary carbon centers has been developed, featuring a broad substrate scope, environmentally benign reaction conditions, and operational simplicity.
- Tang, Shi-Zhong,Bian, Hong-Li,Zhan, Zong-Song,Chen, Meng-En,Lv, Jian-Wei,Xie, Shaolei,Zhang, Fu-Min
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p. 12377 - 12380
(2018/11/30)
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- Clean borrowing hydrogen methodology using hydrotalcite supported copper catalyst
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The catalytic activity of Mg-Al hydrotalcite supported copper catalyst was investigated for clean CC and CN bond forming reactions using alcohols as alkylating agent via borrowing hydrogen methodology. The catalyst showed excellent conversion of ketone and amine substrates (71-99%) to alkylated products with high selectivity in alkylation reactions.
- Dixit, Manish,Mishra, Manish,Joshi, Pradyuman A.,Shah, Dinesh O.
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- Conducting moisture sensitive reactions under mechanochemical conditions
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Dry organic solvents are used for various organic reactions that employ moisture sensitive reagents. The processes to dry these solvents are hazardous and costly. Setting up reactions in an open atmosphere while using moisture sensitive reagents has little to no effect on the rate or yield of the reaction under mechanochemical conditions. We believe this is partly due to the gaseous nature of the water vapor in the air compared to the dissolved water and oxygen in solution.
- Waddell, Daniel C.,Clark, Tammara D.,MacK, James
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scheme or table
p. 4510 - 4513
(2012/10/07)
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- Palladium-catalyzed intramolecular hydroalkylation of alkenyl- β-keto esters, α-aryl ketones, and alkyl ketones in the presence of Me 3SiCl or HCI
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Reaction of 3-butenyl β-keto esters or 3-butenyl α-aryl ketones with a catalytic amount of [PdCl2(CH3CN)2] (2) and a stoichiometric amount of Me3SiCl or Me3SiCl/ CuCl2 in dioxane at 25-70°C formed 2-substituted cyclohexanones in good yield with high regioselectivity. This protocol tolerated a number of ester and aryl groups and tolerated substitution at the allylic, enolic, and cis and trans terminal olefinic positions. In situ NMR experiments indicated that the chlorosilane was not directly involved in palladium-catalyzed hydroalkylation, but rather served as a source of HCl, which presumably catalyzes enolization of the ketone. Identification of HCl as the active promoter of palladium-catalyzed hydroalkylation led to the development of an effective protocol for the hydroalkylation of alkyl 3-butenyl ketones that employed sub-stoichiometric amounts of 2, HCl, and CuCl2 in a sealed tube at 70°C.
- Han, Xiaoqing,Wang, Xiang,Pei, Tao,Widenhoefer, Ross A.
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p. 6333 - 6342
(2007/10/03)
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- Palladium-catalyzed intramolecular hydroalkylation of unactivated olefins with dialkyl ketones
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(Matrix presented) Treatment of 3-butenyl heptyl ketone with substoichiometric amounts of PdCl2(CH3CN)2 (10 mol%), HCl (0.1 equiv), and CuCl2 (0.3 equiv) in dioxane at 70°C for 12 h in a sealed tube formed 2-hexylcyclohexanone in 77% isolated yield. A number of alkyl 3-butenyl ketones underwent hydroalkylation under these conditions to form 2-substituted cyclohexanones in moderate to good yield.
- Wang, Xiang,Pei, Tao,Han, Xiaoqing,Widenhoefer, Ross A.
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p. 2699 - 2701
(2007/10/03)
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- Catalytic oxidation of alkyl- and cycloalkylcyclanones into lactones
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Pilot-plant syntheses of alkyl and cycloalkylcyclanones and their subsequent liquid-phase oxidation into lactones are described. Characteristics of resulting intermediates and target products are reported.
- Abbasov,Alimardanov,Suleimanova
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p. 621 - 626
(2007/10/03)
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- Tin(IV) enolates from allylic O-stannyl ketyls: reactions with alkyl halides and HMPA
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The mild free radical reaction of an α,β-unsaturated ketone and tributyltin radical produced a resonance-stabilized allylic O-stannyl ketyl intermediate. A subsequent hydrogen atom transfer produced a tin(IV) enolate which reacts readily with activated halides and HMPA to provide a useful and mild alternative to analogues Li-NH3 alkylations.
- Enholm, Eric J.,Whitley, Paul E.
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p. 559 - 562
(2007/10/02)
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- Reactions of tin(IV) enolates obtained from O-stannyl ketyls under neutral free radical conditions
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Under mild and neutral free radical conditions, an α,β-unsaturated ketone reacted with tributyltin hydride to produce an intermediate resonance-stabilized allylic O-stannyl ketyl. Upon subsequent hydrogen atom abstraction, a tin(IV) enolate was afforded which could be quenched with a variety of electrophiles and form new carbon-carbon bonds. Aldehydes react to produce aldol-type products and both intramolecular and intermolecular carbonyl addition reactions were investigated using this strategy. Using similar methodology, the tin(IV) enolate could be quenched in the presence of HMPA with various alkyl halides and α,β-unsaturated carbonyl compounds (Michael acceptors) to yield alkylated products in good yields. These reactions represent a very mild regioselective alternative to metal enolate formation which usually requires strong bases such as LDA or strongly reductive dissolving metal conditions to achieve success. New carbon skeletons for natural product synthesis can be readily constructed using this chemically neutral approach.
- Enholm, Eric J.,Whitley, Paul E.,Xie, Yongping
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p. 5384 - 5390
(2007/10/03)
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- Synthesis of 2-Alkylcyclohexanones Using Solvent-free Conditions and Microwave Technology
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An expeditious solvent-free route to 2-alkylcyclohexanones from 2-ethoxycarbonylcyclohexanone is described via a solid-liquid phase transfer catalysed alkylation using ButOK as base and Aliquat 336 as catalyst and a LiBr-H2O-NBu4Br induced dealkoxycarbonylation under microwave activation in a focused open-vessel Maxidigest system.Yields were >/= 75percent over two steps.
- Barnier, Jean Pierre,Loupy, Andre,Pigeon, Philippe,Ramdani, Mohamed,Jacquault, Patrick
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p. 397 - 398
(2007/10/02)
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- Synthesis of Medium Ring Ethers. Part 2. Synthesis of the Fully Saturated Carbon Skeleton of Laurencia Non-terpenoid Ether Metabolites Containing Seven-, Eight- and Nine-membered Rings
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A general method for the construction of medium ring ethers is described in which a 2-substituted cycloalkanone was subjected to a Baeyer-Villiger ring expansion to the lactone, Tebbe methylenation of which afforded the enol ether which was subjected to a hydroboration-oxidation sequence to afford the 2,n-disubstituted oxacycle (n = ring size).Application of this procedure has led to efficient syntheses of the fully saturated skeletons corresponding to the naturally occurring Laurencia metabolites containing 2,n-dialkyl substituted seven- (isolaurepan), eight- (lauthisan and laurenan) and nine-membered (obtusan) ethers.
- Carling, Robert W.,Clark, J. Stephen,Holmes, Andrew B.
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- Polycyclic phenols, alcohols and ketones from phenols, cyclic alcohols and cyclic ketones using a nickel oxide/manganese oxide/magnesium oxide catalyst in presence of at least one of hydrogen and nitrogen
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At least one of a polycyclic phenol, a polycyclic alcohol and a polycyclic ketone is produced under hydrogenation conditions using a nickel oxide/manganese oxide/magnesium oxide catalyst by subjecting at least one of a monocyclic ketone, a monocyclic alcohol and a monocyclic phenol to said conditions and said catalyst.
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