- SF5-Enolates in Ti(IV)-Mediated Aldol Reactions
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The F···Ti bonding in the transition structures determines high trans- and syn-diastereoselectivities for aldol reactions of SF5-acetates with aldehydes in the presence of TiCl4 in the non-nucleophilic solvent CH2Cl2
- Ponomarenko, Maksym V.,Grabowsky, Simon,Pal, Rumpa,R?schenthaler, Gerd-Volker,Fokin, Andrey A.
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Read Online
- A new method for synthesis of methyl arylpropiolates by direct heck coupling of aryl iodide and methyl propiolate in presence of K2CO3
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A protocol for the efficient direct cross coupling of esters of propiolic acid and of aryl iodides with a Pd(PPh3)2Cl2/copper(I) iodide catalyst system in the presence of K2CO3 has been developed.
- Eckert, Thomas,Ipaktschi, Junes
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Read Online
- Z-Selective phosphine promoted 1,4-reduction of ynoates and propynoic amides in the presence of water
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Phosphine-mediated reductions of substituted propynoic esters and amides in the presence of water yield the partially reduced α,β-unsaturated esters and amides with highZ-selectivity. The competitivein situ ZtoE-isomerization of the product in some cases lowers theZtoEratios of the isolated α,β-unsaturated carbonyl products. Reaction time and the amounts of phosphine and water in the reaction mixture are the key experimental factors which control the selectivity by preventing or reducing the rates ofZ- toE-product isomerization. Close reaction monitoring enables isolation of theZ-alkenes with high selectivities. The computational results suggest that the reactions could be highlyZ-selective owing to the stereoselective formation of theE-P-hydroxyphosphorane intermediate.
- Drikermann, Denis,Kupfer, Stephan,Seifert, Fabian,Steinmetzer, Johannes,Vilotijevic, Ivan,Zi, You
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supporting information
p. 6092 - 6097
(2021/07/21)
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- trans-Selective hydrocyanation of ynoates, ynones and ynoic acids catalyzed by nucleophilic phosphines
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trans-Selective hydrocyanation of ynoates and ynones in the presence of TMSCN and an alcohol additive are catalyzed by nucleophilic phosphines. The trisubstituted E-olefin products of anti-addition of hydrogen cyanide to the alkyne are produced with high regio- and stereoselectivity. The alcohol additive reacts with TMSCN to produce hydrogen cyanide in situ. Ynoic acids undergo the phosphine catalyzed hydrocyanation in the presence of TMSCN under aprotic conditions only. In these reactions, TMSCN reacts with the acid to generate hydrogen cyanide and the silyl ester which, unlike the acid, undergoes phosphine catalyzed hydrocyanation and gives the stereo-defined E-2-cyano-acrylic acids after work up.
- Meyer, Maximilian,Peri?, Milica,Sch?mberg, Fritz,Vilotijevi?, Ivan
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supporting information
(2021/10/04)
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- Co3O4 nanoparticles embedded in triple-shelled graphitic carbon nitride (Co3O4/TSCN): a new sustainable and high-performance hierarchical catalyst for the Pd/Cu-free Sonogashira–Hagihara cross-coupling reaction
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Inspired by the synthesis of triple-shelled periodic mesoporous organosilica hollow spheres, a straightforward and controllable approach for the preparation of Co3O4 NPs embedded in triple-shelled graphitic carbon nitride has been es
- Ghodsinia, Sara S. E.,Akhlaghinia, Batool,Jahanshahi, Roya
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p. 3217 - 3244
(2021/05/17)
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- Esterification or Thioesterification of Carboxylic Acids with Alcohols or Thiols Using Amphipathic Monolith-SO3H Resin
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We have developed a method for the esterification of carboxylic acids with alcohols using amphipathic, monolithic-resin bearing sulfonic acid moieties as cation exchange functions (monolith-SO3H). Monolith-SO3H efficiently catalyzed the esterification of aromatic and aliphatic carboxylic acids with various primary and secondary alcohols (1.55.0 equiv) in toluene at 6080 °C without the need to remove water generated during the reaction. The amphipathic property of monolith-SO3H facilitates dehydration due to its capacity for water absorption. This reaction was also applicable to thioesterification, wherein the corresponding thioesters were obtained in excellent yield using only 2.0 equiv of thiol in toluene, although heating at 120 °C was required. Moreover, monolith-SO3H was separable from the reaction mixtures by simple filtration and reused for at least five runs without decreasing the catalytic activity.
- Ichihara, Shuta,Ishida, Moeka,Ito, Ryo,Kato, Ayumu,Monguchi, Yasunari,Nakamura, Shinji,Park, Kwihwan,Sajiki, Hironao,Takada, Hitoshi,Wakayama, Fumika,Yamada, Tsuyoshi,Yamada, Yutaro
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p. 2702 - 2710
(2022/01/19)
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- Synthesis method of aryl-substituted alkyne
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The invention relates to the technical field of synthesis of aryl substituted alkyne, and discloses a synthetic method of an aryl-substituted alkyne, and discloses a synthesis method of an aryl-substituted alkyne. Aryl boronic acid and divalent copper compounds, 8 - hydroxyquinoline, an oxidizing agent and an inorganic base are added to the reaction solvent, and the aryl substituted alkyne is obtained by stirring and separating after stirring at room temperature. Compared with the existing sonogashira reaction, the synthesis method disclosed by the invention realizes the aryl reaction of the lean electron alkyne through the oxidative coupling reaction, avoids Sonogashira reaction required precious palladium catalyst, can react at room temperature, and is mild in reaction condition and high in product yield.
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Paragraph 0031; 0036-0038
(2021/10/20)
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- Enantioselective Fluorination of α-Branched β-Ynone Esters Using a Cinchona-Based Phase-Transfer Catalyst
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Herein, we report the fluorination of α-branched β-ynone esters to afford their corresponding quaternary fluorinated products with good enantioselectivity (ee = 73-90%) using a cinchona-based phase-transfer catalyst. α-Branched β-ynone esters possess a highly acidic α-proton and form their corresponding enolate as a single isomer, which allows the enantioselective fluorination reaction to occur under standard cinchona-based phase-transfer catalyst conditions. Moreover, the obtained α-fluorinated product can be treated with [(SPhos)AuNTf2] (1 mol %) to afford a fluorinated 3,5-diketo carboxylic acid.
- Arimitsu, Satoru,Iwasa, Satsuki,Arakaki, Ryunosuke
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supporting information
p. 12804 - 12812
(2020/10/09)
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- Organocatalytic trans Phosphinoboration of Internal Alkynes
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We report the first trans phosphinoboration of internal alkynes. With an organophosphine catalyst, alkynoate esters and the phosphinoboronate Ph2P-Bpin are efficiently converted into the corresponding trans-α-phosphino-β-boryl acrylate products in moderate to good yield with high regio- and Z-selectivity. This reaction operates under mild conditions and demonstrates good atom economy, requiring only a modest excess of the phosphinoboronate. X-ray crystallography experiments allowed structural assignment of the unprecedented and densely functionalized (Z)-α-phosphino-β-boryl acrylate products.
- Fritzemeier, Russell G.,Nekvinda, Jan,Rosenblum, Carol Ann,Santos, Webster L.,Slebodnick, Carla,Vogels, Christopher M.,Westcott, Stephen A.
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supporting information
p. 14358 - 14362
(2020/07/04)
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- Ynamide-Mediated Intermolecular Esterification
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An ynamide-mediated one-pot, two-step intermolecular esterification via the condensation of carboxylic acids with nucleophilic hydroxyl species was reported. A broad substrate scope with respect to carboxylic acids, alcohols, and phenols was observed. The α-acyloxyenamide intermediates formed by the addition of carboxylic acids to ynamides proved to be effective acylating reagents for the esterification of alcohol and phenol derivatives with the assistance of base catalysis. Notably, the racemization of the α-chiral center of carboxylic acids can be avoided.
- Wang, Xuewei,Yang, Yang,Zhao, Yongli,Wang, Sheng,Hu, Wenchang,Li, Jinmei,Wang, Zihao,Yang, Fengling,Zhao, Junfeng
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p. 6188 - 6194
(2020/05/26)
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- Synthesis of 1-Amino-2 H-quinolizin-2-one Scaffolds by Tandem Silver Catalysis
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An efficient tandem cycloisomerization-amination reaction catalyzed by silver is described. This rapid and atom-economic reaction delivered 1-amino-2H-quinolizin-2-one scaffolds in high yields under mild conditions. The reaction could be extended to an asymmetric version albeit with moderate enantioselective excess of the products. In addition, the products can be easily reduced into various azabicycles containing 4-pyridones, which are important building blocks in organic synthesis.
- Min, Xiao-Long,Sun, Chao,He, Ying
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supporting information
p. 724 - 728
(2019/02/21)
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- Efficient Access to Chiral β-Borylated Carboxylic Esters via Rh-Catalyzed Hydrogenation
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Rh/bisphosphine?thiourea ligand (ZhaoPhos)-catalyzed asymmetric hydrogenation of (Z)-β-substituted-β-boryl-α,β-unsaturated esters was successfully developed, furnishing a variety of chiral β-borylated carboxylic esters with high yields and excellent enantioselectivities (up to 99% yield and >99% ee). The gram-scale asymmetric hydrogenation was performed efficiently in the presence of only 0.05 mol% (S/C=2 000) catalyst loading with full conversion, 99% yield and 99% ee. Moreover, the hydrogenation product was easily converted to other versatile synthetic intermediates, such as methyl (S)-3-hydroxy-3-phenylpropanoate and methyl (S)-3-(furan-2-yl)-3-phenylpropanoate. (Figure presented.).
- Liu, Gang,Li, Anqi,Qin, Xueyuan,Han, Zhengyu,Dong, Xiu-Qin,Zhang, Xumu
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supporting information
p. 2844 - 2848
(2019/04/26)
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- N-triflyl-propiolamides: Preparation and transamidation reactions
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N-Trifluoromethylsulfonyl-propiolamides have been prepared by two methods: a) N-triflation of secondary acetylenic carboxanilides, prepared in two steps from terminal alkynes, with triflic anhydride (Tf2O) and b) from terminal alkynes and an aryl or alkyl isocyanate followed by Tf2O in a consecutive one-pot reaction. The title compounds are bench-stable and insensitive to water and alcohols but amenable to transamidation reactions with a wide range of amine nucleophiles. Conversely, they are excellent reagents for the propynoylation of ammonia, primary and secondary amines, anilines, and hydrazines.
- Fiore, Vito A.,Maas, Gerhard
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p. 3586 - 3595
(2019/05/27)
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- Synthesis of Chiral β-Borylated Carboxylic Esters via Nickel-Catalyzed Asymmetric Hydrogenation
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The highly efficient Ni-catalyzed asymmetric hydrogenation of β-boronic ester substituted-α,β-unsaturated carboxylic esters was successfully developed using (S,S)-Ph-BPE as the ligand. A series of chiral β-borylated carboxylic esters were obtained with high yields (94%-99% yields) and excellent enantioselectivities (89%-99% ee). The gram-scale asymmetric hydrogenation with a low catalyst loading (0.25 mol %) and synthetic transformation of hydrogenation product demonstrated the great synthetic utility of this methodology.
- Han, Zhengyu,Liu, Gang,Zhang, Xianghe,Li, Anqi,Dong, Xiu-Qin,Zhang, Xumu
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supporting information
p. 3923 - 3926
(2019/06/14)
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- A One-Pot Sonogashira Coupling and Annulation Reaction: An Efficient Route toward 4 H -Quinolizin-4-ones
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An efficient one-pot Sonogashira coupling and annulation reaction affording 4 H -quinolizin-4-ones in moderate to excellent yields is described. A variety of substituted iodoarenes and 2-alkylazaarenes were well tolerated, and especially the unsaturated double and triple bonds were compatible under the standard conditions.
- Chen, Zhengwang,Liu, Tanggao,Ma, Xiaoyue,Liang, Pei,Long, Lipeng,Ye, Min
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p. 863 - 867
(2019/04/25)
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- Cobalt(III)-Catalyzed Intermolecular Carboamination of Propiolates and Bicyclic Alkenes via Non-Annulative Redox-Neutral Coupling
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A cobalt(III)-catalyzed, redox-neutral, intermolecular carboamination of propiolates and bicyclic alkenes was developed. This non-annulative coupling strategy features atom economy, high regioselectivity, good yields, and functional groups tolerance. Such a carboamination reaction was applied to modified phenols from the corresponding phenols under mild conditions.
- Zhu, Yuelu,Chen, Feng,Zhao, Xinyang,Yan, Dingyuan,Yong, Wanxiong,Zhao, Jing
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supporting information
p. 5884 - 5888
(2019/08/20)
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- Palladium-Catalyzed Regio- and Stereoselective Sulfonylation of Aryl Propiolates with Sulfonyl Hydrazides: Access to (E)-β-Aryl Sulfonyl Acrylates
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An efficient method for the synthesis of (E)-β-aryl sulfonyl acrylates has been reported. This palladium-catalyzed approach showed excellent regio- and stereoselectivity in the sulfonylation of aryl propiolates with sulfonyl hydrazides. Through this approach, a wide range of (E)-β-aryl sulfonyl acrylates were obtained in moderate to high yields. (Figure presented.).
- Jiang, Huanfeng,Yan, Wuxin,Huang, Jiuzhong,Tan, Chaowei,Zhan, Lingzhi,Wu, Wanqing
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supporting information
p. 4575 - 4580
(2019/09/16)
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- TEMPO-Me: An Electrochemically Activated Methylating Agent
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Bench- and air-stable 1-methoxy-2,2,6,6-tetramethylpiperidine (TEMPO-Me) is relatively unreactive at ambient temperature in the absence of an electrochemical stimulus. In this report, we demonstrate that the one-electron electrochemical oxidation of TEMPO-Me produces a powerful electrophilic methylating agent in situ. Our computational and experimental studies are consistent with methylation proceeding via a SN2 mechanism, with a strength comparable to the trimethyloxonium cation. A protocol is developed for the electrochemical methylation of aromatic acids using TEMPO-Me.
- Norcott, Philip L.,Hammill, Chelsey L.,Noble, Benjamin B.,Robertson, Johnathon C.,Olding, Angus,Bissember, Alex C.,Coote, Michelle L.
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supporting information
p. 15450 - 15455
(2019/11/02)
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- Salt-Free Strategy for the Insertion of CO2 into C?H Bonds: Catalytic Hydroxymethylation of Alkynes
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A copper(I) catalyst enables the insertion of carbon dioxide into alkyne C?H bonds by using a suitable organic base with which hydrogenation of the resulting carboxylate salt with regeneration of the base becomes thermodynamically feasible. In the presence of catalytic copper(I) chloride/4,7-diphenyl-1,10-phenanthroline, polymer-bound triphenylphosphine, and 2,2,6,6-tetramethylpiperidine as the base, terminal alkynes undergo carboxylation at 15 bar CO2 and room temperature. After filtration, the ammonium alkynecarboxylate can be hydrogenated to the primary alcohol and water at a rhodium/molybdenum catalyst, regenerating the amine base. This demonstrates the feasibility of a salt-free overall process, in which carbon dioxide serves as a C1 building block in a C?H functionalization.
- Wendling, Timo,Risto, Eugen,Krause, Thilo,Goo?en, Lukas J.
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supporting information
p. 6019 - 6024
(2018/03/27)
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- Trans -Hydroboration vs. 1,2-reduction: Divergent reactivity of ynones and ynoates in Lewis-base-catalyzed reactions with pinacolborane
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Ynones and ynoates react with pinacolborane in a divergent manner in the presence of nucleophilic phosphine catalysts. Ynones are transformed to the corresponding propargyl alcohols in good yields with high regio- and chemoselectivity. Ynoates undergo highly regio- and stereoselective trans-hydroboration to produce E-vinylboronates. Impressive divergence in reactivity of ynones and ynoates can be traced back to the mechanistic aspects of 1,2-reduction and trans-hydroboration. A comparative analysis of the two pathways paints a complex picture in which different reaction rates control selectivity in these seemingly unrelated processes and explains how sufficiently acidic protons in the reaction mixtures can be used to steer the selectivity in different directions.
- Zi, You,Sch?mberg, Fritz,Seifert, Fabian,G?rls, Helmar,Vilotijevic, Ivan
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supporting information
p. 6341 - 6349
(2018/09/10)
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- Cobalt(III)-Catalyzed Construction of Benzofurans, Benzofuranones and One-Pot Orthogonal C?H Functionalizations to Access Polysubstituted Benzofurans
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Benzofuran and benzofuranone derivatives have been synthesized through exclusive 5-exo-dig intramolecular hydroarylation using the amide-directed, cost-effective, high-valent Cp*CoIII-catalytic system. Challenging one-pot, orthogonal C?H functionalizations using two different electrophiles are also reported to afford polysubstituted benzofurans. Several valuable functional group interconversions along with removal of the amide directing group provide a route to access several diversely functionalized benzofurans. The mechanistic study suggests a reversible cobaltation step is operative here. (Figure presented.).
- Bera, Sourav Sekhar,Debbarma, Suvankar,Jana, Sripati,Maji, Modhu Sudan
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supporting information
p. 2204 - 2210
(2018/06/07)
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- Transition Metal-Free Trans Hydroboration of Alkynoic Acid Derivatives: Experimental and Theoretical Studies
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We report a phosphine-catalyzed trans hydroboration of alkynoate esters and amides. The reaction proceeds under mild conditions with exclusive (E)-selectivity to afford (E)-β-boryl acrylates and (E)-β-boryl acrylamides in good to excellent yields. The reaction is tolerant of a variety of functional groups and allows efficient access to novel oxaboroles as well as a pargyline derivative (MAO inhibitor). Theoretical calculations suggest an internal hydride generates a phosphonium allenoxyborane followed by the formation of a key phosphonocyclobutene intermediate that collapses in a stereoselective, rate-limiting step.
- Fritzemeier, Russell,Gates, Ashley,Guo, Xueying,Lin, Zhenyang,Santos, Webster L.
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p. 10436 - 10444
(2018/07/21)
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- Sequential protocol for C(sp)–H carboxylation with CO2: KOtBu-catalyzed C(sp)–H silylation and KOtBu-mediated carboxylation
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CO2 incorporation into C–H bonds is an important and interesting topic. Herein a sequential protocol for C(sp)–H carboxylation by employing a metal-free C–H activation/catalytic silylation reaction in conjunction with KOtBu-mediated carboxylation with CO2 was established, in which KOtBu catalyzes silylation of terminal alkynes to form alkynylsilanes at low temperature, and simultaneously mediates carboxylation of the alkynesilanes with atmospheric CO2. Importantly, the carboxylation further promotes the silylation, which makes the whole reaction proceed very rapidly. Moreover, this methodology is simple and scalable, which is characterized by short reaction time, wide substrate scope, excellent functional-group tolerance and mild reaction conditions, affording a range of corresponding propiolic acid products in excellent yields in most cases. In addition, it also allows for a convenient 13C-labeling through the use of 13CO2.
- Yu, Bo,Yang, Peng,Gao, Xiang,Yang, Zhenzhen,Zhao, Yanfei,Zhang, Hongye,Liu, Zhimin
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p. 449 - 456
(2018/02/06)
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- An electrochemical method for carboxylic ester synthesis from N-alkoxyamides
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An electrochemical method for the synthesis of carboxylic as well as hindered esters from N-alkoxyamides has been reported. The electrochemical reaction proceeds through constant current electrolysis (CCE) by taking advantage of the dual role of n-Bu4NI (TBAI) as the redox catalyst as well as the supporting electrolyte. Besides providing mild reaction conditions, the present protocol is free from external oxidants and conducting salts, thereby generating nitrogen as the nonhazardous side product. Additionally, the developed procedure is highly advantageous due to its short reaction time, wide substrate scope, and gram-scale synthesis.
- Subramanian, Kripa,Yedage, Subhash L.,Bhanage, Bhalchandra M.
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p. 10025 - 10032
(2018/05/31)
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- One-pot synthesis of propynoates and propynenitriles
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An efficient transformation towards propynoates and propynenitriles is herein described. The practical methodology was conducted at low temperature (-78 or -60 °C) in a one-pot manner with the assistance of base rather than any transition metal catalysts. The base-induced protocol exhibits good functional group tolerance (up to 28 examples) and high efficiency (up to 92% yields) towards substituted acetylenes of great synthetic significance, which was also well demonstrated by the gram-scale reactions.
- Shu, Fan,Zheng, Qingjuan,Dong, Wanrong,Peng, Zhihong,An, Delie
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p. 144 - 148
(2017/02/10)
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- CsF-promoted carboxylation of aryl(hetaryl) terminal alkynes with atmospheric CO2 at room temperature
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A CsF-promoted carboxylation of aryl(hetaryl) terminal alkynes with atmospheric CO2 in the presence of trimethylsilylacetylene was developed to give functionalized propiolic acid products at room temperature. A wide range of propiolic acids bearing functional groups was successfully obtained in good to excellent yields. Mechanistic studies demonstrate that in the carboxylation process the alkynylsilane intermediate was first in situ generated, which was then trapped by CO2, giving rise to the corresponding functionalized propiolic acids after acidification. The advantages of this approach include avoiding use of transition-metal catalysts, wide substrate scope together with excellent functional group tolerance, ambient conditions and a facile work-up procedure.
- Yu,Yang,Gao,Yang,Zhao,Zhang,Liu
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supporting information
p. 9250 - 9255
(2017/08/29)
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- Palladium-Catalyzed Ylidyl-Carbonylation of Aryl Halides to Produce α-Acylphosphoranes
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An efficient synthesis of α-acylphosphoranes by palladium-catalyzed carbonylation of aryl iodides with carbon monoxide and stabilized phosphonium ylides has been developed. Featuring 44 examples, the protocol displayed a wide substrate scope under mild reaction conditions, showcasing its potential in synthetic organic chemistry.
- Guo, Xiaojun,Ma, Wei,Xue, Dong,Wang, Chao,Xiao, Jianliang
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supporting information
p. 4824 - 4827
(2016/10/14)
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- Oxidative Alkoxycarbonylation of Alkynes by Means of Aryl α-Diimine Palladium(II) Complexes as Catalysts
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The straightforward in situ synthesized bis(2,6-diisopropyl)acenaphthenequinonediimine palladium triflate catalyst was generally employed for both the mono-alkoxycarbonylation of terminal alkynes, and the bis-alkoxycarbonylation of 1,2-disubstituted alkynes by using mild reaction conditions [carbon monoxide pressure (PCO)=4 bar, temperature=20 °C]. Utilizing low catalyst loading (down to 0.5 mol%), a variety of propiolic esters were synthesized with good to excellent isolated yields. Most importantly the system was very efficient not only with methanol but also with a range of different alcohols, starting from the less hindered benzyl alcohol to the most hindered ones, such as isopropyl alcohol and tert-butyl alcohol. In addition, aromatic and aliphatic 1,2-disubstituted alkynes were converted into maleic acid derivatives, together with an acid-catalyzed isomerization reaction, showing modest to good selectivity and excellent combined yields. In particular 3-hexyne showed a satisfactory degree of selectivity for the maleic diesters of methanol and benzyl alcohol, obtaining the corresponding products with good isolated yields. (Figure presented.).
- Beltrani, Michela,Carfagna, Carla,Milani, Barbara,Mancuso, Raffaella,Gabriele, Bartolo,Fini, Francesco
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p. 3244 - 3253
(2016/10/21)
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- Copper-Catalyzed Domino Synthesis of Benzo[4,5]imidazo[1,2-a]pyrimidin-4(10H)-ones using Cyanamide as a Building Block
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An efficient and practical copper-catalyzed domino synthesis of benzo[4,5]imidazo[1,2-a]pyrimidin-4(10H)-ones has been developed. The protocol uses N-(2-halophenyl)-3-alkylpropiolamides and cyanamide as the starting materials, inexpensive copper(I) iodide and pipecolinic acid as the catalyst and ligand, and the corresponding products were obtained in moderate to good yields.
- Lou, Zhenbang,Wu, Xudong,Yang, Haijun,Zhu, Changjin,Fu, Hua
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supporting information
p. 3961 - 3968
(2016/01/25)
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- One-pot tandem hydrophenylation and ionic hydrogenation of 3-phenylpropynoic acid derivatives under superelectrophilic activation
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The reactions of esters and amides of 3-phenylpropynoic acid with strong Lewis acids AlX3 (X = Cl, Br) or conjugate Br?nsted-Lewis superacids HX-AlX3 (X = Cl, Br) in benzene and cyclohexane at room temperature afforded 3,3-diphenylpropanoic acid derivatives in up to 94% yield. This tandem reaction of the acetylene bond proceeded by hydrophenylation followed by ionic hydrogenation.
- Nilov, Denis I.,Vasilyev, Aleksander V.
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p. 5714 - 5717
(2015/09/29)
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- A Strained Disilane-Promoted Carboxylation of Organic Halides with CO2 under Transition-Metal-Free Conditions
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By using a strained four-membered ring disilane (3,4-benzo-1,1,2,2-tetraethyldisilacyclobutene) and CsF, a wide range of aryl, alkenyl, alkynyl, benzyl, allyl, and alkyl halides was successfully carboxylated under an ambient CO2 atmosphere (CO2 balloon) at room temperature within 2 h. In this carboxylation, a highly reactive silyl anion, which is generated from the disilane and CsF, is a key to facilitating the formation of a carbanion equivalent. The resulting anionic species can be trapped with CO2 to produce carboxylic acids with high efficiency.
- Mita, Tsuyoshi,Suga, Kenta,Sato, Kaori,Sato, Yoshihiro
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supporting information
p. 5276 - 5279
(2015/11/18)
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- Ligand-Assisted Gold-Catalyzed Cross-Coupling with Aryldiazonium Salts: Redox Gold Catalysis without an External Oxidant
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Gold-catalyzed C(sp)-C(sp2) and C(sp2)-C(sp2) cross-coupling reactions are accomplished with aryldiazonium salts as the coupling partner. With the assistance of bpy ligand, gold(I) species were oxidized to gold(III) by diazonium without any external oxidants. Monitoring the reaction with NMR and ESI-MS provided strong evidence for the nitrogen extrusion followed by AuIII reductive elimination as the key step.
- Cai, Rong,Lu, Mei,Aguilera, Ellen Y.,Xi, Yumeng,Akhmedov, Novruz G.,Petersen, Jeffrey L.,Chen, Hao,Shi, Xiaodong
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p. 8772 - 8776
(2015/11/27)
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- Copper(I)-based ionic liquid-catalyzed carboxylation of terminal alkynes with CO2 at atmospheric pressure
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An ionic liquid containing copper(I) proved to be an effective homogeneous catalyst for the carboxylation of terminal alkynes with ambient CO2. This developed procedure needs no external ligands and terminal alkynes with various groups proceeded smoothly at atmospheric CO2 pressure and room temperature. Interestingly, the ILs containing copper(I) in both the anion and the cation showed much higher activity in comparison with the counterparts incorporating copper(I) solely in the form of halocuprate, that is, copper(I) in the anion. Especially, activated effect of the terminal alkyne by the ionic liquid was also validated by the NMR technique.
- Xie, Jia-Ning,Yu, Bing,Zhou, Zhi-Hua,Fu, Hong-Chen,Wang, Ning,He, Liang-Nian
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supporting information
p. 7059 - 7062
(2015/11/27)
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- Copper(I)@carbon-catalyzed carboxylation of terminal alkynes with CO2 at atmospheric pressure
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Activated carbon supported CuBr was found to be an efficient catalyst for the carboxylation of terminal alkynes under atmospheric pressure of CO2 using ethylene carbonate as solvent at 80 °C for only 2 h, as verified with 13CO2. Various terminal alkynes could react smoothly with CO2 and organic halides under the reaction conditions to afford the corresponding carboxylic esters. In addition, the catalyst can be easily recovered and reused at least five times without significant loss of activity.
- Yu, Bing,Xie, Jia-Ning,Zhong, Chun-Lai,Li, Wei,He, Liang-Nian
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p. 3940 - 3944
(2015/11/11)
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- Investigation of quantitative structure-reactivity relationships in the aliphatic Claisen rearrangement of bis-vinyl ethers reveals a dipolar, dissociative mechanism
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Kinetic investigations of substituent effects in the thermal rearrangement of bis-vinyl ether substrates are reported. Findings indicate that the influence of the various substituent patterns on the rate of rearrangement in these compounds differs from that documented in the literature for the analogous [3,3]-sigmatropic rearrangement of allyl vinyl ethers. In addition, the thermochemical data collected suggests the existence of a dissociative transition state with significant dipolar character. These findings provide a unique contribution to the already extensive body of literature dedicated to mechanistic investigation of the Claisen rearrangement of aliphatic allyl vinyl ethers.
- O'Rourke, Natasha F.,Wulff, Jeremy E.
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p. 1292 - 1308
(2014/03/21)
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- Stereoselective silylcupration of conjugated alkynes in water at room temperature
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Micellar catalysis enables copper-catalyzed silylcupration of a variety of electron-deficient alkynes, thereby providing access to isomerically pure E- or Z-β-silyl-substituted carbonyl derivatives. These reactions take place in minutes, afford high yields and stereoselectivity, and are especially tolerant of functional groups present in the substrates. The aqueous reaction medium has been successfully recycled several times, and a substrate/catalyst ratio of 10,000:1 has been documented for this methodology. Fast, cheap, and green: Micellar catalysis enables the selective construction of a variety β-silyl-substituted carbonyl derivatives under mild aqueous conditions. The reaction is catalyzed by low levels of CuI, is compatible with numerous electron-withdrawing groups, affords high yields, and provides opportunities for scale-up and recycling of the reaction medium. The environmental impact, as measured by E Factors, is very low.
- Linstadt, Roscoe T. H.,Peterson, Carl A.,Lippincott, Daniel J.,Jette, Carina I.,Lipshutz, Bruce H.
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supporting information
p. 4159 - 4163
(2014/05/06)
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- A convenient regioselective synthesis of cyclopentadienones via palladium-catalyzed [2+2+1] cyclocarbonylation of alkynes
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A simple and efficient synthesis of cyclopentadienones via palladium-catalyzed cyclocarbonylation of alkynes under atmospheric pressure of carbon monoxide has been developed. The transformation was carried out under mild and ligand-free conditions, a wide range of substrates and exceptional functional group tolerance.
- Xu, Yanli,Zhao, Jinwu,Chen, Huoji,Wu, Wanqing,Jiang, Huanfeng
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supporting information
p. 2488 - 2490
(2014/03/21)
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- Gold and palladium combined for the Sonogashira coupling of aryl and heteroaryl halides
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A highly efficient gold and palladium combined methodology for the Sonogashira coupling of a wide array of electronically and structurally diverse aryl and heteroaryl halides is described. The orthogonal reactivity of the two metals shows high selectivity and extreme functional group tolerance in Sonogashira coupling. A brief mechanistic study reveals that the gold acetylide intermediate enters into the palladium catalytic cycle at the transmetalation step. Georg Thieme Verlag Stuttgart.New York.
- Panda, Biswajit,Sarkar, Tarunk.
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p. 817 - 829
(2013/04/10)
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- Synthesis of α,β-alkynyl esters and unsymmetrical maleate esters catalyzed by pd/c; An efficient phosphine-free catalytic system for oxidative alkoxycarbonylation of terminal alkynes
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Pd/C-catalyzed oxidative alkoxycarbonylation of terminal alkynes using alcohols in the presence of tetrabutylammonium iodide under CO/O2 (5:1 atm) has been investigated. The desired α,β-alkynyl esters and unsymmetrical maleate esters are formed in good to excellent yields under different reaction conditions. The present protocol eliminates the use of phosphine ligands and has straightforward catalyst recovery. The catalyst was recycled up to six times without significant loss of catalytic activity. Georg Thieme Verlag Stuttgart . New York.
- Gadge, Sandip T.,Bhanage, Bhalchandra M.
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supporting information
p. 981 - 986
(2013/06/27)
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- Carboxylation of alkynylsilanes with carbon dioxide mediated by cesium fluoride in DMSO
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The facile syntheses of a variety functionalized propiolic acids were achieved by carboxylation of alkynylsilanes with carbon dioxide mediated by cesium fluoride under ambient conditions. This journal is The Royal Society of Chemistry 2013.
- Yonemoto-Kobayashi, Misato,Inamoto, Kiyofumi,Tanaka, Yoshiyuki,Kondo, Yoshinori
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supporting information
p. 3773 - 3775
(2014/03/21)
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- CuII-exchanged montmorillonite K10 clay-catalyzed direct carboxylation of terminal alkynes with carbon dioxide
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A new, simple and straight-forward protocol for direct carboxylation of terminal alkynes has been developed using CuII-montmorillonite K10 clay as a heterogeneous catalyst and CO2 as the C1 carbon feedstock. Also coupling of terminal alkynes with CO2 (1 atm) in the presence of alkyl halides has been achieved under the same reaction conditions, thereby providing access to a variety of functionalized alkyl-2-alkynoates in high yields.
- Aher, Ravindra D.,Gade, Madhuri H.,Reddy, R. Santhosh,Sudalai, Arumugam
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p. 1325 - 1329,5
(2020/08/31)
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- Platinum-catalyzed hydrosilylations of internal alkynes: Harnessing substituent effects to achieve high regioselectivity
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Rule of thumb: The high yielding title reaction is described with a focus on understanding the factors that govern the regioselectivity of the process (see scheme). Electronic, steric, and functional group properties all influence the selectivity, an understanding of which allows the selective formation of trisubstituted vinylsilanes, which are synthetically useful compounds for accessing stereodefined alkenes. Copyright
- Rooke, Douglas A.,Ferreira, Eric M.
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supporting information; experimental part
p. 3225 - 3230
(2012/05/31)
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- Cationic rhodium(I)-catalyzed regioselective tandem heterocyclization/[3+2] cycloaddition of 2-(1-alkynyl)-2-alken-1-ones with alkynes
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RhI in two minds: A RhI-catalyzed tandem heterocyclization/[3+2] cycloaddition reaction was developed that provides rapid, efficient, and stereoselective access to highly substituted cyclopenta[c]furans from readily available 2-(1-alkynyl)-2-alken-1-ones and alkynes (see scheme). The cationic RhI acts as both a Lewis acid and a conventional transition-metal catalyst, providing the first example of a RhI species acting as a Lewis acid. Copyright
- Gao, Hongyin,Zhang, Junliang
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supporting information; experimental part
p. 2777 - 2782
(2012/04/04)
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- Organocatalytic one-pot oxidative cleavage of terminal diols to dehomologated carboxylic acids
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The organocatalytic one-pot oxidative cleavage of terminal 1,2-diols to one-carbon-unit-shorter carboxylic acids is described. The combination of 1-Me-AZADO (cat.), NaOCl (cat.), and NaClO2 caused smooth one-pot oxidative cleavage under mild conditions. A broad range of substrates including carbohydrates and N-protected amino diols were converted without epimerization. Terminal triols and tetraols respectively underwent cleavage of their C-2 and C-3 moieties to afford their corresponding two- and three-carbon-unit-shorter carboxylic acids.
- Shibuya, Masatoshi,Doi, Ryusuke,Shibuta, Takuro,Uesugi, Shun-Ichiro,Iwabuchi, Yoshiharu
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supporting information
p. 5006 - 5009
(2013/01/15)
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- CARBOXYLATION OF TERMINAL ALKYNES
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The present invention describes a process for converting a terminal alkyne into an alkynoic acid. In this process the alkyne is exposed to carbon dioxide in the presence of a copper (I) species, a base and a complexing agent capable of complexing copper (I).
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Page/Page column 26
(2011/07/07)
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- Copper-catalyzed, aerobic oxidative cross-coupling of alkynes with arylboronic acids: Remarkable selectivity in 2,6-lutidine media
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Aerobic oxidative cross-coupling reactions between alkynes and boronic acids under mild conditions catalyzed by low loadings of a copper salt are reported. 2,6-Lutidine accelerated the reactions dramatically, and the desired coupling products were obtained in high yields with high selectivities.
- Yasukawa, Tomohiro,Miyamura, Hiroyuki,Kobayashi, Sh
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supporting information; experimental part
p. 6208 - 6210
(2011/10/10)
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- Chelating carboxylic acid amides as robust relay protecting groups of carboxylic acids and their cleavage under mild conditions
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Free choice: Carboxamides of bispicolylamine are alternative protecting groups for carboxylic acids (see scheme). As a consequence of their straightforward applicability, their high chemical stability towards a broad range of conditions, and their selective cleavage under mild conditions to give either carboxylic acids or their methyl esters, this new protection method should find widespread application in the realm of organic synthesis. Copyright
- Broehmer, Manuel C.,Mundinger, Stephan,Braese, Stefan,Bannwarth, Willi
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p. 6175 - 6177
(2011/08/03)
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- Synthesis of symmetrical and unsymmetrical diarylalkynes from propiolic acid using palladium-catalyzed decarboxylative coupling
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Figure presented. Symmetrical diarylalkynes were obtained from propiolic acid (or 2-butynedioic acid) and aryl halides in good yields. The optimized reaction conditions were 2.0 equiv of aryl halide, 1.0 equiv of propiolic acid, 5.0 mol % Pd(PPh3/su
- Park, Kyungho,Bae, Goun,Moon, Jeongju,Choe, Jaehoon,Song, Kwang Ho,Lee, Sunwoo
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scheme or table
p. 6244 - 6251
(2010/12/20)
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- Hollow palladium-cobalt bimetallic nanospheres as an efficient and reusable catalyst for Sonogashira-type reactions
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The synthesis and characterization of hollow Pd-Co bimetallic nanospheres are reported. During Sonogashira-type coupling reactions between aryl halides and terminal alkynes in aqueous medium, these hollow materials exhibited much higher activity than the solid counterpart nanoparticles. Moreover, the catalytic activity could be adjusted via changing the catalyst composition. The enhanced activity was attributed to both the hollow chamber structure and the promotional effect of Co-dopants, which provided more Pd active sites for the reactants. The Royal Society of Chemistry 2010.
- Li, Hui,Zhu, Zhonghong,Liu, Jun,Xie, Songhai,Li, Hexing
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experimental part
p. 4366 - 4370
(2011/08/09)
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- Oxoammonium salt/NaClO2: An expedient, catalytic system for one-pot oxidation of primary alcohols to carboxylic acids with broad substrate applicability
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A facile, green, one-pot oxidation of primary alcohols to carboxylic acids with broad substrate applicability has been developed by employing an expedient catalytic system consisting of 1-Me-AZADO+X-/NaClO 2. The Royal Society of Chemistry.
- Shibuya, Masatoshi,Sato, Takahisa,Tomizawa, Masaki,Iwabuchi, Yoshiharu
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supporting information; experimental part
p. 1739 - 1741
(2009/08/08)
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- Polymer-supported palladium perfluorooctanesulfonate [Pd(OPf)2]: A recyclable and ligand-free palladium catalyst for copper-free Sonogashira coupling reaction in water under aerobic conditions
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Amberlyst A-21, a kind of well-known and cheap polymeric material, was treated with palladium perfluorooctanesulfonate [Pd(OPf)2] giving a reagent with a palladium loading of 1.94 (wt%). The polymer-supported fluorous palladium catalyzes the highly efficient Sonogashira coupling reaction in water. The reactions can be performed under copper- and ligand-free conditions in an air atmosphere. The palladium catalyst is easily separated and can be reused several times without a significant loss of catalytic activity.
- Ye, Zhi-Wen,Yi, Wen-Bin
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experimental part
p. 1124 - 1128
(2009/04/11)
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