- Formation of Fluorinated Amido Esters through Unexpected C3?C4 Bond Fission in 4-Trifluoromethyl-3-oxo-β-lactams
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4-Trifluoromethyl-3-oxo-β-lactams were unexpectedly transformed into 2-[(2,2-difluorovinyl)amino]-2-oxoacetates as major products, accompanied by minor amounts of 2-oxo-2-[(2,2,2-trifluoroethyl)amino]acetates, upon treatment with alkyl halides and triethylamine in DMSO. This peculiar C3?C4 bond fission reactivity was investigated in-depth, from both an experimental and a computational point of view, in order to shed light on the underlying reaction mechanism.
- Dao Thi, Hang,Goossens, Hannelore,Hertsen, Dietmar,Otte, Valerie,Van Nguyen, Tuyen,Van Speybroeck, Veronique,D'hooghe, Matthias
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- Metal- and Solvent-Free Transesterification and Aldol Condensation Reactions by a Homogenous Recyclable Basic Ionic Liquid Based on the 1,3,5-Triazine Framework
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A new recyclable basic ionic liquid was introduced as an efficient catalyst for aldol condensation and transesterification reactions under environmentally friendly conditions. The catalyst was prepared based on methyl imidazolium moieties bearing hydroxide counter anions via the Hofmann elimination on a 1,3,5-triazine framework. The ionic liquid with two functionalities including anion stabilizer and high basicity, was used as an efficient catalyst for aldol condensation as well as transesterification reaction of a variety of alkyl benzoates. All reactions were performed in the absence of any external reagent, co-catalyst, or solvent, in line with environmental protection. The kinetics isotope effect (KIE) was conducted for the transesterification reaction to elucidate the mechanism and rate determining step (RDS). It worth noted that, the homogeneous catalyst could be recycled from the reaction mixture and reused for several consecutive runs with insignificant drop of basicity and conversion.
- Hu, Yanqiu,Kazemnejadi, Milad,Ren, Mingqi
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p. 775 - 783
(2021/08/30)
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- Electrochemical esterification via oxidative coupling of aldehydes and alcohols
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An electrolytic method for the direct oxidative coupling of aldehydes with alcohols to produce esters is described. Our method involves anodic oxidation in presence of TBAF as supporting electrolyte in an undivided electrochemical cell equipped with graphite electrodes. This method successfully couples a wide range of alcohols to benzaldehydes with yields ranging from 70 to 90%. The protocol is easy to perform at a constant voltage conditions and offers a sustainable alternative over conventional methods.
- Smeyne, Dylan,Verboom, Katherine,Bryan, Maria,LoBue, James,Shaikh, Abid
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supporting information
(2021/03/26)
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- LiHMDS: Facile, highly efficient and metal-free transesterification under solvent-free condition
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Transesterification is one of the important organic reactions employed in numerous industrial as well as laboratory applications for the synthesis of various esters. Herein, we report a rapid, highly efficient, and transition metal-free transesterification reaction in the presence of LiHMDS under solvent-free conditions. The transesterification reaction was carried out with three different benzoate esters and a wide range of primary and secondary alcohols (from C3-C18) in good to excellent yields (45 examples). By considering the commercial role of esters, this method will be promising for the facile synthesis of esters in industry-relevant applications.
- Gore, Kiran R.,Mittapelli, Lavanya L.
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- Copper-mediated simple and direct aerobic oxidative esterification of arylacetonitriles with alcohols/phenols
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A simple and direct aerobic oxidative esterification reaction of arylacetonitriles with alcohols/phenols is achieved in the presence of a copper salt and molecular oxygen, which produces a broad range of aryl carboxylic acid esters in good to high yields. Copper salt plays multiple roles in the transformation, which allows the oxygenation of C-H bond, cleavage of inert C-C bond, and formation of C-O bond in one pot without the assistance of any of the acids, bases, ligands, and so on. The reaction provides a simple, direct, and efficient protocol towards functionalized esters, especially aryl benzoates, from readily available starting materials.
- Dong, Jianyu,Chen, Xiuling,Ji, Fangyan,Liu, Lixin,Su, Lebin,Mo, Min,Tang, Jian-Sheng,Zhou, Yongbo
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- Metal nitrate-catalyzed one-pot oxidative esterification of benzaldehyde with hydrogen peroxide in alcoholic solutions at room temperature
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The activity of metal nitrate catalysts was investigated in the oxidative esterification reactions of benzaldehyde with hydrogen peroxide. Several types of metal nitrates (alkaline, alkaline earth, and transition metals) were evaluated as catalysts. Among the assessed salts, Fe(NO3)3 was the most efficient catalyst toward the formation of the target product (i.e., benzoic alkyl ester). In methyl alcohol, benzaldehyde was selectively oxidized to benzoic acid and then esterified to methyl benzoate. The efficiency of the catalyst was correlated with its higher Lewis acidity character, which was established through the pH measurements of methanolic solutions of the soluble metal nitrate salts. The influence of main variables of the reaction, such as catalyst load, temperature, and reactant stoichiometry, was investigated. The size of the carbon chain and steric hindrance played an essential role in the reaction selectivity. While methyl and ethyl alcohols selectively provided ester as the main product (ca. 70-75%) and acetal as the subproduct, the other alcohols gave ester, hemiacetal, and benzoic acid, which was formed in the least amount. The use of an inexpensive catalyst, a green oxidant, mild conditions, and short reaction times were the positive aspects of this one-pot process. The high TON (ca. 900) is evidence of the high catalytic activity of Fe(NO3)3. It is noteworthy that this methodology does not rely upon ligands and other additives.
- Da Silva, Márcio José,De Oliveira, Cesar Macedo
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p. 3683 - 3691
(2021/03/03)
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- Alkali-modified heterogeneous Pd-catalyzed synthesis of acids, amides and esters from aryl halides using formic acid as the CO precursor
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To establish an environmentally friendly green chemical process, we minimized and resolved a significant proportion of waste and hazards associated with conventional organic acids and molecular gases, such as carbon monoxide (CO). Herein, we report a facile and milder reaction procedure, using low temperatures/pressures and shorter reaction time for the carboxyl- and carbonylation of diverse arrays of aryl halides over a newly developed cationic Lewis-acid promoted Pd/Co3O4catalyst. Furthermore, the reaction proceeded in the absence of acid co-catalysts, and anhydrides for CO release. Catalyst reusability was achievedviascalable, safer, and practical reactions that provided moderate to high yields, paving the way for developing a novel environmentally benign method for synthesizing carboxylic acids, amides, and esters.
- Fapojuwo, Dele Peter,Maqunga, Nomathamsanqa Prudence,Meijboom, Reinout,Mogudi, Batsile M.,Molokoane, Pule Petrus,Onisuru, Oluwatayo Racheal,Oseghale, Charles O.
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p. 26937 - 26948
(2021/08/17)
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- N-Aroylbenzotriazoles as Efficient Reagents for o-Aroylation in Absence of Organic Solvent
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N-Aroylbenzotriazoles have been shown to be efficient reagents for esterification in the absence of organic solvent. Grinding of N-aroylbenzoytiazoles with twofold excess of alcohols for a couple of hours at room temperature gave corresponding esters in high percentage of yields.
- Hahnvajanawong, Viwat,Phungpis, Baramee
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p. 2671 - 2674
(2021/10/25)
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- Palladium-Catalyzed Para-Selective Difluoromethylation of Arene Esters
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Highly efficient, palladium-catalyzed, para-selective difluoromethylation of arene esters has been developed using [1,1′-biphenyl]-2-dicyclohexylphosphine as the effective ligand. A wide variety of arene esters bearing various functional groups were all compatible with the reaction conditions, leading to para-difluoromethylated products in moderate to good yields. Moreover, benzoylamide and benzenesulfonamide were also well-tolerated, suggesting that this novel catalyst system has broad applications to a variety of substrates.
- Tu, Guangliang,Wang, Dongjie,Yuan, Chunchen,Zhang, Jingyu,Zhao, Yingsheng
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p. 10740 - 10749
(2020/09/18)
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- Synthesis of a B12-BODIPY dyad for B12-inspired photochemical transformations of a trichloromethylated organic compound
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A B12complex-BODIPY dyad was synthesized by peripheral modification of cobalamin derivatives. The photophysical properties of the dyad were investigated by UV-vis, PL, and transient absorption spectroscopy. A visible light-driven dechlorination reaction of a trichlorinated organic compound, DDT, was reported. The dyad showed efficient catalysis for dechlorination under N2with turnover numbers of over 220 for the reaction. One-pot syntheses of an ester and amide from DDT and benzotrichloride were also achieved using the dyad under air.
- Anai, Yuki,Shichijo, Keita,Fujitsuka, Mamoru,Hisaeda, Yoshio,Shimakoshi, Hisashi
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p. 11945 - 11948
(2020/10/15)
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- Palladium-catalyzed aryloxy- and alkoxycarbonylation of aromatic iodides in γ-valerolactone as bio-based solvent
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Fossil-based solvents and triethylamine as a toxic and volatile base were successfully replaced with γ-valerolactone as a non-volatile solvent and K2CO3 as inorganic base in the alkoxy- and aryloxycarbonylation of aryl iodides using phosphine-free Pd catalyst systems. By this, the traditional systems were not simply replaced but also significantly improved. In the study, the effects of different reaction parameters, i.e. the use of several other solvents, the temperature, the carbon monoxide pressure, the base and the catalyst concentrations, were evaluated in details on the efficiency of the carbonylations. To gather some information on the mechanism of these reactions, the effects of the electronic parameters (σ) of various aromatic substituents of the aryl iodides as well as the influence of para-substitution of phenol were investigated on the activity. For a comparison, the aryl-substituted aryl iodides were also reacted with methanol and aryl iodide was also alkoxycarbonylated using several different lower alcohols. From the observed correlations between the electronic parameters of the aromatic substituents and the rates, it appears that the rate determining step is the oxidative addition of Ar–I to Pd0, provided that sufficient amounts of nucleophiles are present for the ester formation. If this is not the case, the rate of nucleophile attack might determine the overall rate.
- Tukacs, József M.,Marton, Bálint,Albert, Eszter,Tóth, Imre,Mika, László T.
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- Electrochemical esterification reaction of alkynes with diols: Via cleavage of carbon-carbon triple bonds without catalyst and oxidant
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A novel electrochemical esterification of alkynes for the synthesis of esters was developed in which diols and their derivatives were used as the partners. This method is green as it is catalyst-free, oxidant-free, and additive-free and shows atom-economy. This is the first example of an electrochemical reaction via cleavage of carbon-carbon triple bonds. Meanwhile, this is also the first example of a carbon-carbon triple bond cleavage reaction of alkynes with diols. This journal is
- Cheng, Hui-Hui,Gao, Hui,Li, Pin-Hua,Shen, Hui-Zhi,Wang, Pei-Long
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supporting information
p. 6783 - 6791
(2020/11/09)
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- The synergistic role of the support surface and Au-Cu alloys in a plasmonic Au-Cu?LDH photocatalyst for the oxidative esterification of benzyl alcohol with methanol
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Layered double hydroxide-supported Au-Cu alloy nanoparticles (NPs) were found to be highly efficient catalysts for the oxidative esterification of benzyl alcohol with methanol in the presence of molecular oxygen under visible-light irradiation to prepare methyl benzoate. Here, we report that alloying small amounts of copper into gold nanoparticles can increase the ability to activate oxygen molecules to O2- radicals and display greater charge heterogeneity to promote the cleavage of the C-H bond of benzyl alcohol molecules by reinforcing the coordination of the intermediate with unsaturated metal active sites due to the LSPR effect of alloy NPs, which is the rate-limiting step of the reaction. Besides the Au-Cu alloy NPs, the support also played a pivotal role in the catalytic process. The support with the presence of acid-base pairs, in which the basic sites served as the reactant molecule adsorption sites to provoke the intermediate formation and the acidic sites promoted the recovery of the support surface, showed better performances by affecting the overall reaction rate completely. Moreover, applying this photocatalyst in the cross-esterification of aromatic alcohols and aliphatic alcohols displayed excellent yields.
- Wang, Xiaoyu,Wang, Ruiyi,Wang, Jie,Fan, Chaoyang,Zheng, Zhanfeng
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p. 1655 - 1664
(2020/01/31)
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- Catalytic conversion of ketones to esters: Via C(O)-C bond cleavage under transition-metal free conditions
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The catalytic conversion of ketones to esters via C(O)-C bond cleavage under transition-metal free conditions is reported. This catalytic process proceeds under solvent-free conditions and offers an easy operational procedure, broad substrate scope with excellent selectivity, and reaction scalability. This journal is
- Subaramanian, Murugan,Ramar, Palmurukan M.,Rana, Jagannath,Gupta, Virendra Kumar,Balaraman, Ekambaram
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supporting information
p. 8143 - 8146
(2020/09/09)
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- Luminescent tungsten(vi) complexes as photocatalysts for light-driven C-C and C-B bond formation reactions
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The realization of photocatalysis for practical synthetic application hinges on the development of inexpensive photocatalysts which can be prepared on a large scale. Herein an air-stable, visible-light-absorbing photoluminescent tungsten(vi) complex which can be conveniently prepared at the gram-scale is described. This complex could catalyse photochemical organic transformation reactions including borylation of aryl halides, such as aryl chloride, reductive coupling of benzyl bromides for C-C bond formation, reductive coupling of phenacyl bromides, and decarboxylative coupling of redox-active esters of alkyl carboxylic acid with high product yields and broad functional group tolerance.
- Chan, Kaai-Tung,Che, Chi-Ming,Du, Lili,Liu, Yungen,Phillips, David Lee,To, Wai-Pong,Tong, Glenna So Ming,Wu, Liang-Liang,Yu, Daohong
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p. 6370 - 6382
(2020/07/15)
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- Facile synthesis of a highly efficient Co/Cu@NC catalyst for base-free oxidation of alcohols to esters
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The direct oxidation of alcohols to esters is an environmentally benign and cost-effective organic synthetic strategy, but it is still a great challenge to discover an economic, highly active, and long-term stable catalyst for efficient transformation of alcohols to esters under milder conditions. Herein, we developed cobalt and copper nanoparticle -co-decorated nitrogen-doped carbon catalysts (CoCu@NCn) through two steps of ball milling and calcination. It was found that CoCu@NCn could catalyze the oxidation of alcohols to esters effectively in the absence of basic additives. The catalytic activity was much higher than those of monometallic Co@NC2 and Cu@NC2 samples, and the catalyst can be conveniently recovered and quite steadily reused. Through a series of control experiments and characterizations, it is concluded that the remarkable catalytic performance of CoCu@NC2 was associated with the synergistic effect between the two metal components, the enhanced basic active sites and the active surface area.
- Jiang, Jiusheng,Li, Xiang,Du, Shengyu,Shi, Langchen,Jiang, Pingping,Zhang, Pingbo,Dong, Yuming,Leng, Yan
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p. 7780 - 7785
(2020/06/09)
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- Metal-Free Oxidative Esterification of Ketones and Potassium Xanthates: Selective Synthesis of α-Ketoesters and Esters
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A novel and efficient oxidative esterification for the selective synthesis of α-ketoesters and esters has been developed under metal-free conditions. In the protocol, various α-ketoesters and esters are available in high yields from commercially available ketones and potassium xanthates. Mechanistic studies have proven that potassium xanthate not only promotes oxidative esterification but also provides an alkoxy moiety for the reaction, which involves the cleavage and reconstruction of C-O bonds.
- Luo, Xianglin,He, Runfa,Liu, Qiang,Gao, Yanping,Li, Jingqing,Chen, Xiuwen,Zhu, Zhongzhi,Huang, Yubing,Li, Yibiao
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p. 5220 - 5230
(2020/05/18)
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- Ni-catalyzed direct alcoholysis of N-acylpyrrole-type tertiary amides under mild conditions
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N-Acylpyrrole-type amides are a class of versatile building blocks in asymmetric synthesis. We report that by employing Ni(COD)2/2,2′-bipyridine (5 mol%) catalytic system, the direct, catalytic alcoholysis of N-acylpyrrole-type aromatic and aliphatic amides with both primary and secondary alcohols can be achieved efficiently under very mild conditions (rt, 1 h) even at gram scale. By increasing the catalyst loading to 10 mol%, prolonging reaction time (18 h), and/or elevating reaction temperature to 50 °C/80 °C, the reaction could be extended to both complex and hindered N-acylpyrroles as well as to N-acylpyrazoles, Nacylindoles, and to other (functionalized) primary and secondary alcohols. In all cases, only 1.5 equiv. of alcohol were used. The value of the method has been demonstrated by the racemization-free, catalytic alcoholysis of chiral amides yielded from other asymmetric methodologies.
- Chen, Hang,Chen, Dong-Huang,Huang, Pei-Qiang
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p. 370 - 376
(2020/03/03)
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- Carbonylative Suzuki coupling and alkoxycarbonylation of aryl halides using palladium supported on phosphorus-doped porous organic polymer as an active and robust catalyst
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Developing highly active catalysts with the combined advantages of molecular and solid catalysis is considered as the “Holy Grail” in the area of catalysis research. Herein, a phosphorus-doped porous polymer-immobilized palladium was successfully developed as an efficient, robust, and recyclable catalyst for the carbonylative Suzuki coupling and alkoxycarbonylation reactions of aryl halides. Rather than just as an immobilizing molecular catalyst, palladium supported on phosphorus-doped porous organic polymer exhibits even better catalytic performances than that of its analogue homogeneous catalysts in both carbonylation reactions. Moreover, the catalyst can be easily separated and reused for at least 5 times without significant loss in reactivity. Importantly, the catalyst was highly stable under carbonylation reaction conditions, and no palladium nanoparticle was observed even after the 5th reuse.
- Wan, Yali,Song, Fangxiang,Ye, Tao,Li, Guangxing,Liu, Dingfu,Lei, Yizhu
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- Aqueous Flow Hydroxycarbonylation of Aryl Halides Catalyzed by an Amphiphilic Polymer-Supported Palladium-Diphenylphosphine Catalyst
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An aqueous continuous-flow reaction system is developed for the palladium-catalyzed hydroxycarbonylation of aryl halides. Flow hydroxycarbonylation of aryl halides in aqueous solution proceeds efficiently in a flow reactor containing a palladium-diphenylphosphine complex immobilized on an amphiphilic polystyrene-poly(ethylene glycol) resin to give the corresponding benzoic acids in excellent yields.
- Osako, Takao,Kaiser, Reinhard,Torii, Kaoru,Uozumi, Yasuhiro
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p. 961 - 966
(2019/05/10)
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- Dehydrogenative cross-coupling of primary alcohols to form cross-esters catalyzed by a manganese pincer complex
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Base-metal-catalyzed dehydrogenative cross-coupling of primary alcohols to form cross-esters as major products, liberating hydrogen gas, is reported. The reaction is catalyzed by a pincer complex of earth-abundant manganese in the presence of catalytic base, without any hydrogen acceptor or oxidant. Mechanistic insight indicates that a dearomatized complex is the actual catalyst, and indeed this independently prepared dearomatized complex catalyzes the reaction under neutral conditions.
- Das, Uttam Kumar,Ben-David, Yehoshoa,Leitus, Gregory,Diskin-Posner, Yael,Milstein, David
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p. 479 - 484
(2019/01/11)
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- Pd-Colloids-Catalyzed/Ag2O-Oxidized General and Selective Esterification of Benzylic Alcohols
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Palladium colloids obtained from the degradation of Hermann–Beller palladacycle proved to be an efficient catalytic system in combination with silver oxide as a selective oxidant for the oxidative esterification of differently substituted benzyl alcohols in MeOH as solvent. Excellent reactivity exhibited by the catalytic system also allowed the alcoholic coupling partner to be changed from MeOH to a wide range of alcohols having diverse functionalities. The mildness of the developed protocol also made it possible to employ propargyl alcohol as the coupling partner without any observation of any interference of the terminal alkyne. Selective oxidative coupling of a primary alcoholic functional group over secondary in the case of glycols and glycerols was also made possible using the developed catalyst system. To test the relevancy of Pd/Ag combined catalysis mixed Pd/Ag colloids were synthesized, characterized by TEM, XRD and XPS and applied to oxidative-esterification successfully.
- Sable, Vaibhav,Shah, Jagrut,Sharma, Anuja,Kapdi, Anant R.
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supporting information
p. 2639 - 2647
(2019/07/08)
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- MnO2?Fe3O4 Magnetic Nanoparticles as Efficient and Recyclable Heterogeneous Catalyst for Benzylic sp3 C?H Oxidation
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Herein, we report a highly chemoselective and efficient heterogeneous MnO2?Fe3O4 MNP catalyst for the oxidation of benzylic sp3 C?H group of ethers using TBHP as a green oxidant to afford ester derivatives in high yield under batch/continuous flow module. This catalyst was also effective for the benzylic sp3 C?H group of methylene derivatives to furnish the ketone in high yield which can be easily integrated into continuous flow condition for scale up. The catalyst is fully characterized by spectroscopic techniques and it was found that 0.424 % MnO2?Fe3O4 catalyzes the reaction; the magnetic nanoparticles of this catalyst could be easily recovered from the reaction mixture. The recovered catalyst was recycled for twelve cycles without any loss of the catalytic activity. The advantages of MnO2?Fe3O4 MNP are its catalytic activity, easy preparation, recovery, and recyclability, gram scale synthesis with a TOF of up to 14.93 h?1 and low metal leaching during the reaction.
- Pandey, Akanksha M.,Agalave, Sandip G.,Vinod, Chathakudath P.,Gnanaprakasam, Boopathy
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supporting information
p. 3414 - 3423
(2019/10/19)
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- Woody species: A new bio-based material for dual Ca/Mg catalysis with remarkable Lewis acidity properties
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Advances in green catalysis have promoted the development of ecocatalysis encountered in most of the main transformations of organic chemistry. Taking advantage of the remarkable capacity of certain plants to hyperaccumulate transition metals into shoots or roots, we have addressed the direct use of metals derived from contaminated plant wastes as supported Lewis acid catalysts, coupling agents, oxidative and reducing catalysts in green chemistry. This approach constituted the first example of chemical catalyst based on phytotechnologies. Herein, we show that the concept can be extended to common and abundant plant species that are surprisingly appropriated for chemical catalysis. We present that willow, birch, plane and linden trees can be used to produce bio-based and original Lewis acid catalysts. The catalytic potential of these species will be illustrated through two representative transformations, acetalisation and oxidative esterification. Thanks to their original polymetallic composition, ecocatalysts provided better results compared to classical metal chlorides such as MgCl2, CaCl2 or ZnCl2. This illustrates the interest of the ecocatalysis and is incorporated within the green and sustainable chemistry concept.
- Deyris, Pierre-Alexandre,Adler, Pauline,Petit, Eddy,Legrand, Yves-Marie,Grison, Claude
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p. 3133 - 3142
(2019/06/18)
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- Synthesis of Esters from Stable and Convenient Sulfoxonium Precursors under Catalyst- And Additive-Free Conditions
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A convenient and efficient procedure for the construction of esters from stable sulfoxonium ylides and alcohols has been developed. This protocol presents a broad substrate scope and good yields of the desired esters can be isolated. Notably, no catalyst, oxidant, base or any other additive is required.
- Wu, Xiao-Feng,Yuan, Yang
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p. 1820 - 1824
(2019/09/09)
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- Dehydrogenative Coupling of Aldehydes with Alcohols Catalyzed by a Nickel Hydride Complex
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A nickel hydride complex, {2,6-(iPr2PO)2C6H3}NiH, has been shown to catalyze the coupling of RCHO and R′OH to yield RCO2R′ and RCH2OH, where the aldehyde also acts as a hydrogen acceptor and the alcohol also serves as the solvent. Functional groups tolerated by this catalytic system include CF3, NO2, Cl, Br, NHCOMe, and NMe2, whereas phenol-containing compounds are not viable substrates or solvents. The dehydrogenative coupling reaction can alternatively be catalyzed by an air-stable nickel chloride complex, {2,6-(iPr2PO)2C6H3}NiCl, in conjunction with NaOMe. Acids in unpurified aldehydes react with the hydride to form nickel carboxylate complexes, which are catalytically inactive. Water, if present in a significant quantity, decreases the catalytic efficiency by forming {2,6-(iPr2PO)2C6H3}NiOH, which causes catalyst degradation. On the other hand, in the presence of a drying agent, {2,6-(iPr2PO)2C6H3}NiOH generated in situ from {2,6-(iPr2PO)2C6H3}NiCl and NaOH can be converted to an alkoxide species, becoming catalytically competent. The proposed catalytic mechanism features aldehyde insertion into the nickel hydride as well as into a nickel alkoxide intermediate, both of which have been experimentally observed. Several mechanistically relevant nickel species including {2,6-(iPr2PO)2C6H3}NiOC(O)Ph, {2,6-(iPr2PO)2C6H3}NiOPh, and {2,6-(iPr2PO)2C6H3}NiOPh·HOPh have been independently synthesized, crystallographically characterized, and tested for the catalytic reaction. While phenol-containing molecules cannot be used as substrates or solvents, both {2,6-(iPr2PO)2C6H3}NiOPh and {2,6-(iPr2PO)2C6H3}NiOPh·HOPh are efficient in catalyzing the dehydrogenative coupling of PhCHO with EtOH.
- Eberhardt, Nathan A.,Wellala, Nadeesha P. N.,Li, Yingze,Krause, Jeanette A.,Guan, Hairong
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p. 1468 - 1478
(2019/04/17)
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- Porous organic cage stabilised palladium nanoparticles: Efficient heterogeneous catalysts for carbonylation reaction of aryl halides
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Porous organic cage stabilised palladium nanoparticles were successfully prepared using methanol as a mild reductant. The as-prepared porous composite materials show high catalytic activity for the carbonylation reaction of aryl halides under mild conditions.
- Zhang, Yong,Xiong, Yu,Ge, Jin,Lin, Rui,Chen, Chen,Peng, Qing,Wang, Dingsheng,Li, Yadong
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supporting information
p. 2796 - 2799
(2018/03/21)
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- Fe-catalyzed esterification of amides via C-N bond activation
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An efficient Fe-catalyzed esterification of primary, secondary, and tertiary amides with various alcohols for the preparation of esters was performed. The esterification process was accomplished with FeCl3$6H2O, which is a stable, inexpensive, environmentally friendly catalyst with high functional group tolerance.
- Chen, Xiuling,Hu, Siying,Chen, Rongxing,Wang, Jian,Wu, Minghu,Guo, Haibin,Sun, Shaofa
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p. 4571 - 4576
(2018/02/09)
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- Superior performance of Co-N/m-C for direct oxidation of alcohols to esters under air
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A convenient, expeditious, and high-efficiency protocol for the transformation of alcohols into esters using a Co-modified N-doped mesoporous carbon material (Co-N/m-C) as the catalyst is proposed. The catalyst was prepared through direct pyrolysis of a macromolecular precursor. The catalyst prepared using a pyrolysis temperature of 900 °C (labeled Co-N/m-C-900) exhibited the best performance. The strong coordination between the ultra-dispersed cobalt species and the pyridine nitrogen as well as the large area of the mesoporous surface resulted in a high turnover frequency value (107.6 mol methyl benzoate mol?1 Co h?1) for the direct aerobic oxidation of benzyl alcohol to methyl benzoate. This value is much higher than those of state-of-the-art transition-metal-based nanocatalysts reported in the literature. Moreover, the catalyst exhibited general applicability to various structurally diverse alcohols, including benzylic, allylic, and heterocyclic alcohols, achieving the target esters in high yields. In addition, a preliminary evaluation revealed that Co-N/m-C-900 can be used six times without significant activity loss. In general, the process was rapid, simple, and cost-effective.
- Li, Ning,Shang, Sensen,Wang, Lianyue,Niu, Jingyang,Lv, Ying,Gao, Shuang
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p. 1249 - 1257
(2018/06/14)
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- Highly Efficient Carbon Monoxide Capture by Carbanion-Functionalized Ionic Liquids through C-Site Interactions
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A novel method for the highly efficient and reversible capture of CO in carbanion-functionalized ionic liquids (ILs) by a C-site interaction is reported. Because of its supernucleophilicity, the carbanion in ILs could absorb CO efficiently. As a result, a relatively high absorption capacity for CO (up to 0.046 mol mol?1) was achieved under ambient conditions, compared with CO solubility in a commonly used IL [Bmim][Tf2N] (2×10?3 mol mol?1). The results of quantum mechanical calculations and spectroscopic investigation confirmed that the chemical interaction between the C-site in the carbanion and CO resulted in the superior CO absorption capacities. Furthermore, the subsequent conversion of captured CO into valuable chemicals with good reactivity was also realized through the alkoxycarbonylation reaction under mild conditions. Highly efficient CO absorption by carbanion-functionalized ILs provides a new way of separating and converting CO.
- Tao, Duan-Jian,Chen, Feng-Feng,Tian, Zi-Qi,Huang, Kuan,Mahurin, Shannon M.,Jiang, De-En,Dai, Sheng
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supporting information
p. 6843 - 6847
(2017/06/06)
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- Acid promoted C-C bond oxidative cleavage of β-O-4 and β-1 lignin models to esters over a copper catalyst
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Depolymerisation of lignin to aromatics is a challenging task. We herein report that a Cu(OAc)2/BF3·OEt2 catalyst is effective in simultaneously cleaving C-C bonds in β-1 and β-O-4 ketones, yielding esters and phenols. In-depth studies show that C-H bond activation is the rate determining step for C-C bond cleavage. BF3·OEt2 promotes the reaction via activating the β-C-H bond. This study offers the potential to obtain aromatic esters from lignin.
- Wang,Li,Lu,Li,Zhang,Liu,Luo,Wang
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p. 702 - 706
(2017/08/15)
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- Practical: In situ -generation of phosphinite ligands for palladium-catalyzed carbonylation of (hetero)aryl bromides forming esters
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An effective method for alkoxycarbonylation of (hetero)aryl bromides is developed in the presence of in situ-generated phosphinite ligands tBu2POR (R = nBu, nPr, Et or Me). For this purpose commercially available tBu2PCl was used as the pre-ligand in the presence of different alcohols. For the first time cross coupling reactions with two alcohols-one generating the ligand, the other used as substrate-were developed. Through this method, ligand optimization can be performed in a more efficient manner and the desired products could be obtained with good yields and selectivity.
- Wang, Lin,Neumann, Helfried,Spannenberg, Anke,Beller, Matthias
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supporting information
p. 7469 - 7472
(2017/07/12)
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- A study on reactions of an alkynylsilane with oxone-KX (X = Cl, Br, I) and its one-pot transformation into an amide/ester
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Oxyhalogenation reactions of a variety of alkynylsilanes were studied using oxone as mild oxidant and KCl, KBr, and KI as halogen sources. In this study, reaction of an alkynylsilane with oxone-KX (X = Cl or Br) produced trichloromethyl/tribromomethyl ketones inhigh yields. Under similar conditions, however, reactions of alkynylsilanes with oxone-KI were found to give exclusively 1,2,2-triiodovinyl derivatives in high yields. In this study, new methods were deveoped for effcient one-pot tranformation of alkynylsilanes into amides and esters by reaction with amines and alcohols respectively via trihalomethyl ketone.
- Sriramoju, Vinodkumar,Jillella, Raveendra,Kurva, Srinivas,Madabhushi, Sridhar
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p. 560 - 562
(2017/03/30)
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- Efficient and selective palladium-catalyzed direct oxidative esterification of benzylic alcohols under aerobic conditions
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A highly efficient palladium-catalyzed approach for the direct oxidative esterification of benzylic alcohols with methanol and long-chain aliphatic alcohols under mild conditions has been achieved. This practical catalyst system exhibits a broad substrate scope and good functional group tolerance. Catalytic amount of Bi(OTf)3 is used as co-catalyst to improve the activity and selectivity of the reactions. A variety of esters are obtained in yields of 43–96%.
- Hu, Yongke,Li, Bindong
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p. 7301 - 7307
(2017/11/29)
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- Activating cobalt nanoparticles via the Mott-Schottky effect in nitrogen-rich carbon shells for base-free aerobic oxidation of alcohols to esters
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Heterogeneous catalysts of inexpensive and reusable transition-metal are attractive alternatives to homogeneous catalysts; the relatively low activity of transition-metal nanoparticles has become the main hurdle for their practical applications. Here, the de novo design of a Mott-Schotfky-type heterogeneous catalyst is reported to boost the activity of a transition-metal nanocatalyst through electron transfer at the metal/nitrogen-doped carbon interface. The Mott-Schottky catalyst of nitrogen-rich carbon-coated cobalt nanoparticles (Co@NC) was prepared through direct polycondensation of simple organic molecules and inorganic metal salts in the presence of g-C3N4 powder. The Co@NC with controllable nitrogen content and thus tunable Fermi energy and catalytic activity exhibited a high turnover frequency (TOF)value (8.12 mol methyl benzoate mol-1 Co h-1) for the direct, base-free, aerobic oxidation of benzyl alcohols to methyl benzoate; this TOF is 30-fold higher than those of the state-of-the-art transitionmetal-based nanocatalysts reported in the literature. The presented efficient Mott-Schottky catalyst can trigger the synthesis of a series of alkyl esters and even diesters in high yields.
- Su, Hui,Zhang, Ke-Xin,Zhang, Bing,Wang, Hong-Hui,Yu, Qiu-Ying,Li, Xin-Hao,Antonietti, Markus,Chen, Jie-Sheng
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p. 811 - 818
(2017/05/17)
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- Amberlyst-15 catalysed oxidative esterification of aldehydes using a H2O2 trapped oxidant as a terminal oxidant
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A simple and efficient method has been developed for the selective oxidative esterification of aldehydes using commercially available Amberlyst-15 as a catalyst. H2O2 released from a clathrate structured 4Na2SO4·2H2O2·NaCl oxidant serves as an efficient source of terminal oxidants. Various aromatic, heteroaromatic, and aliphatic aldehydes undergo selective esterification to give good to excellent yield. The heterogeneous catalyst, Amberlyst-15, exhibits high reactivity and can be recycled over several runs. The 4Na2SO4·2H2O2·NaCl oxidant was found to be superior to commonly used oxidizing agents providing an anhydrous, easy to handle and stable form of H2O2
- Gayakwad, Eknath M.,Patil, Vilas V.,Shankarling, Ganapati S.
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p. 2695 - 2701
(2017/04/03)
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- Direct oxidation of aldehydes to methyl esters with urea hydrogen peroxide and p-toluenesulfonyl chloride
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Combination of urea hydrogen peroxide and p-toluenesulfonyl chloride in methanol was proved to be facile and highly efficient for the oxidative methyl esterification of various aldehydes to the corresponding carboxylic methyl esters.
- Jeong, Deuk Jun,Lee, Su Bin,Lee, Jong Chan
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p. 725 - 728
(2017/12/28)
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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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- DBU-Based Dicationic Ionic Liquids Promoted Esterification Reaction of Carboxylic Acid with Primary Chloroalkane Under Mild Conditions
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Abstract: A series of DBU-based (DBU = 1, 8-diazabicyclo [5.4.0] undec-7-ene) dicationic ionic liquids with different anions were successfully synthesized by the reaction of DBU and 1, 6-dichlorohexane. Therein, the dicationic ionic liquid 1, 1′-(hexane-1, 6-diyl)bis(1, 8-diazabicyclo [5.4.0]undec-7-enium) dichlorine (IL-1) was successfully employed as an efficient catalyst in esterification reaction of carboxylic acids with primary chloroalkanes under mild conditions without any additional basic reagents. Moreover, the optimum catalyst could be efficiently reused for five times without any significant change on the catalytic effect. The improved protocol is not only efficient, but also green and pollution-free.
- Liu, Yang,Mao, Guijie,Zhao, Hongyan,Song, Jinyi,Han, Huatao,Li, Zhuofei,Chu, Wenyi,Sun, Zhizhong
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p. 2764 - 2771
(2017/09/14)
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- Synthesis of Esters by Functionalisation of CO2
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The invention relates to a method for (I) producing a carboxylic ester of formula (I). Said method comprises the steps of: a) bringing an organosilane/borane of formula Si or B into contact with CO2, in the presence of a catalyst and an electrophilic compound of formula (III), the groups R1, R2, R3, R4, R5, Y, and M′ being as defined in claim 1; and optionally b) recovering the compound of formula (I) produced.
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Paragraph 0130
(2017/09/06)
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- Zinc-Catalyzed Esterification of N-β-Hydroxyethylamides: Removal of Directing Groups under Mild Conditions
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Amide transformations involving C–N bond cleavage are recognized as difficult reactions owing to the inert nature of amides resulting from resonance. Accordingly, a strong inductive effect and geometrical distortion reasonably decrease the resonance stabilization to attenuate the C–N linkage. Although the conversion of such activated amides has been studied intensively, reaction systems for “unactivated” amides are underdeveloped. We herein report that a zinc(II) trifluoromethanesulfonate [Zn(OTf)2] catalyst achieves the esterification of a wide range of unactivated tertiary amides with the assistance of intramolecular acyl rearrangement. The reaction was applied to the one-pot removal of various amide-based directing groups under mild reaction conditions to afford the corresponding esters in high yields.
- Nishii, Yuji,Hirai, Takahiro,Fernandez, Sarah,Knochel, Paul,Mashima, Kazushi
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p. 5010 - 5014
(2017/09/21)
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- Electrolysis of trichloromethylated organic compounds under aerobic conditions catalyzed by the B12 model complex for ester and amide formation
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The electrolysis of benzotrichloride at -0.9 V vs. Ag/AgCl in the presence of the B12 model complex, heptamethyl cobyrinate perchlorate, in ethanol under aerobic conditions using an undivided cell equipped with a platinum mesh cathode and a zinc plate anode produced ethylbenzoate in 56% yield with 92% selectivity. The corresponding esters were obtained when the electrolysis was carried out in various alcohols such as methanol, n-propanol, and i-propanol. Benzoyl chloride was detected by GC-MS during the electrolysis as an intermediate for the ester formation. When the electrolysis was carried out under anaerobic conditions, partially dechlorinated products, 1,1,2,2-tetrachloro-1,2-diphenylethane and 1,2-dichlorostilibenes (E and Z forms), were obtained instead of an ester. ESR spin-trapping experiments using 5,5,-dimethylpyrroline N-oxide (DMPO) revealed that the corresponding oxygen-centered radical and carbon-centered radical were steadily generated during the electrolyses under aerobic and anaerobic conditions, respectively. Applications of the aerobic electrolysis to various organic halides, such as substituted benzotrichlorides, are described. Furthermore, the formation of amides with moderate yields by the aerobic electrolysis of benzotrichloride catalyzed by the B12 model complex in the presence of amines in acetonitrile is reported.
- Shimakoshi, Hisashi,Luo, Zhongli,Inaba, Takuya,Hisaeda, Yoshio
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p. 10173 - 10180
(2016/07/06)
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- Fe-Catalyzed Aerobic Oxidative C-CN Bond Cleavage of Arylacetonitriles Leading to Various Esters
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Fe-catalyzed aerobic oxidative esterifications of arylacetonitriles with alcohols, tri alkoxsilanes, silicate esters, or borate esters have been developed. The acyl groups which were in situ generated via chemoselective C(CO)-CN bond cleavage were directly used as electrophiles, leading to corresponding aryl esters in good to excellent yields under molecular oxygen when attacked by alcohols or alcohol surrogates. Dioxygen serves as both oxidant and reactant in this protocol. The reaction has a very broad substrate scope. Cheap starting materials as well as environmentally benign and inexpensive iron catalyst and ideal oxidant O2 feature this transformation and make it a practical and sustainable protocol to afford esters.
- Kong, Weiguang,Li, Bingnan,Xu, Xuezhao,Song, Qiuling
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p. 8436 - 8443
(2016/09/28)
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- Oxidative esterification via photocatalytic C-H activation
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Direct oxidative esterification of alcohol via photocatalytic C-H activation has been developed using VO@g-C3N4 catalyst; an expeditious esterification of alcohols occurs under neutral conditions using visible light as the source of energy.
- Verma, Sanny,Baig, R. B. Nasir,Han, Changseok,Nadagouda, Mallikarjuna N.,Varma, Rajender S.
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p. 251 - 254
(2015/12/31)
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- A microwave-assisted highly practical chemoselective esterification and amidation of carboxylic acids
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The ubiquitousness of esters and amide functionalities makes their coupling reaction one of the most sought-after organic transformations. Herein, we have described an efficient microwave-assisted synthesis of esters and amides. Soluble triphenylphosphine, in conjugation with molecular iodine, gave the desired products without the requirement for a base/catalyst. In addition, a solid-phase synthetic route is incorporated for the said conversion, which has added advantages over solution-phase pathways, such as low moisture sensitivity, easy handling, isolation of the product by simple filtration, and reusability. In short, our method is simple, mild, green, and highly chemoselective in nature.
- Pathak, Gunindra,Das, Diparjun,Rokhum, Lalthazuala
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p. 93729 - 93740
(2016/10/21)
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- Oxygen-Controlled Catalysis by Vitamin B12-TiO2: Formation of Esters and Amides from Trichlorinated Organic Compounds by Photoirradiation
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An oxygen switch in catalysis of the cobalamin derivative (B12)-TiO2 hybrid catalyst for the dechlorination of trichlorinated organic compounds has been developed. The covalently bound B12 on the TiO2 surface transformed trichlorinated organic compounds into an ester and amide by UV light irradiation under mild conditions (in air at room temperature), while dichlorostilbenes (E and Z forms) were formed in nitrogen from benzotrichloride. A benzoyl chloride was formed as an intermediate of the ester and amide, which was detected by GC-MS. The substrate scope of the synthetic strategy is demonstrated with a range of various trichlorinated organic compounds. A photo-duet reaction utilizing the hole and conduction band electron of TiO2 in B12-TiO2 for the amide formation was also developed.
- Shimakoshi, Hisashi,Hisaeda, Yoshio
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supporting information
p. 15439 - 15443
(2016/01/26)
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- Palladium supported on triphenylphosphine functionalized porous organic polymer: A highly active and recyclable catalyst for alkoxycarbonylation of aryl iodides
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An efficient method for the alkoxycarbonylation of aryl iodides using palladium supported on triphenylphosphine functionalized porous organic polymer (Pd@KAPs(Ph-PPh3)) as the catalyst is reported. Under balloon pressure of CO, various aryl iodides on carbonylation with alcohols and phenols give the corresponding products in moderate to excellent yields (74-96%). The catalyst can be easily separated by simple filtration process and recycled up to ten times without significant decrease in activity. The salient features of this protocol are the simplicity in handling of the catalyst, low CO pressure, negligible palladium leaching and good catalyst recyclability.
- Lei, Yizhu,Wu, Linjuan,Zhang, Xuefeng,Mei, Hui,Gu, Yanlong,Li, Guangxing
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p. 164 - 169
(2015/02/19)
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- Carboxyl activation of 2-mercapto-4,6-dimethylpyrimidine through n-acyl-4,6-dimethylpyrimidine-2-thione: A chemical and spectrophotometric investigation
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2-Mercapto-4,6-dimethylpyrimidine, as effective carboxyl activating group, has been successfully proved by converting it into respective acyl derivatives and the subsequent conversion to the amides and esters respectively using amines, amino alcohols and alcohols. The aminolysis and esterification were monitored chemically and spectrophotometrically. This paved way to establish that the above mercaptopyrimidine derivative is an efficient carboxyl activating group applicable in solid phase peptide synthesis.
- Rajan
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p. 287 - 291
(2015/01/30)
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- Conversion of a metal-organic framework to N-doped porous carbon incorporating Co and CoO nanoparticles: Direct oxidation of alcohols to esters
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A Co-based metal-organic framework, ZIF-67, has been exploited as a selflate to afford N-doped porous carbon incorporating Co NPs with surface-oxidized CoO species, which exhibit excellent catalytic activity, selectivity and magnetic recyclability toward the direct oxidation of alcohols to esters with O2 as a benign oxidant under mild conditions.
- Zhou, Yu-Xiao,Chen, Yu-Zhen,Cao, Lina,Lu, Junling,Jiang, Hai-Long
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supporting information
p. 8292 - 8295
(2015/05/13)
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- Selective Monoesterification of Symmetrical Diols Using Resin-Bound Triphenylphosphine
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Coupling reactions to make esters and amides are among the most widely used organic transformations. We report efficient procedures for amide bond formation and for the monoesterification of symmetrical diols in excellent yields without any requirement for high dilution or slow addition using resin-bound triarylphosphonium iodide. Easy purification, low moisture sensitivity, and good to excellent yields of the products are the major advantages of this protocol.
- Pathak, Gunindra,Rokhum, Lalthazuala
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supporting information
p. 483 - 487
(2015/09/22)
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