- HOMOMOLECULAR ESTERIFICATION OF ALDEHYDES CATALYZED BY HYDRIDOTETRAKIS(TRIPHENYLPHOSPHINE)RHODIUM(I)
-
Homomolecular esterification of benzaldehyde has been carried out under mild conditions using RhH(PPh3)4 as catalyst.A kinetic study of the reaction has revealed a law rate of the form r=k2.The rate-limiting step in the mechanism is the complexation of the second aldehyde molecule with the catalyst.As expected from this result, the lactonisation of ortho-phthalaldehyde is instantaneous at 19 deg C.In this homomolecular esterification RhH(PPh3)3 is the catalytic species and slowly transfers its hydrogen ligand to benzaldehyde to form benzyl alcohol in concentration less than half of that of the catalyst.The complex Rh(PPh3)3 which is formed also catalyses the homomolecular esterification, but 1.6 times less readily than RhH(PPH3s)3.
- Massoui, M.,Beaupere, D.,Nadjo, L.,Uzan, R.
-
-
Read Online
- Palladium nanoparticles immobilized on magnetic nanoparticles: An efficient semi-heterogeneous catalyst for carbonylation of aryl bromides
-
We describe a method for supporting palladium nanoparticles on magnetic nanoparticles modified with amino-functionalized dihydro-imidazolium groups. This catalytic system is very efficient in alkoxy- and amino-carbonylation reactions of aryl bromides. The catalyst can be easily recovered from the reaction mixture by applying an external magnetic field and reused for over five consecutive cycles without a significant decrease in its activity.
- Dutta, Bishnu,Omar, Suheir,Natour, Suzana,Abu-Reziq, Raed
-
-
Read Online
- Bisphosphine phenol and phenolate complexes of Mn(i): Manganese(i) catalyzed Tishchenko reaction
-
We synthesized new organomanganese complexes using the phenolic "pincer" type ligand H-POP. The coordination chemistry of H-POP with Mn(i) was explored, revealing a wide range of binding motifs. Finally, we found that complex 1 catalyzes the formation of benzyl benzoate from benzaldehyde in a Tishchenko reaction.
- Kadassery, Karthika J.,MacMillan, Samantha N.,Lacy, David C.
-
-
Read Online
- Catalytic, high-speed Tishchenko reaction using (2,7-dimethyl-1,8-biphenylenedioxy)bis(diisopropoxyaluminum) as a powerful bidentate catalyst
-
Exceedingly high-speed Tishchenko reaction of various aldehydes can be realized by using a powerful, bidentate aluminum catalyst. This catalytic system is also applicable to the highly stereoselective intramolecular Tishchenko reduction of β-hydroxy ketones.
- Ooi, Takashi,Miura, Tomoya,Takaya, Keisuke,Maruoka, Keiji
-
-
Read Online
- Modification of mesoporous silicate SBA-15 with tris[bis(trimethylsilyl) amido]samarium and its utility in Tishchenko reaction
-
Treatment of mesoporous silicate SBA-15 with Sm[N(SiMe3) 2]3 led to the formation of a novel organolanthanide/ inorganic hybrid material [SBA-15]Sm[N(SiMe3)2] x via abstraction of N(SiMe3)2 by terminal silanol groups and subsequent surface silylation. The hybrid material was characterized by elemental analyses, IR spectroscopy, X-ray diffraction, and nitrogen sorption, indicating a successful tailoring inside the silicate SBA-15 and the maintenance of the well-ordered mesostructure. This hybrid material is a promising heterogeneous catalyst for the Tishchenko reaction, where it is superior to the homogeneous correspondent in deactivation behavior, reusability and relative tolerance to oxygen, particularly in the control of selectivity of mixed Tishchenko reaction due to the steric hindrance and the diffusion control derived from the surface confinement.
- Chen, Yinghua,Zhu, Zhenyu,Zhang, Jie,Shen, Jianzhong,Zhou, Xigeng
-
-
Read Online
- Superbase-promoted acylation of hindered alcohols
-
The commercially available nonionic superbase P(MeNCH2CH2)3N (1a) is very useful for the acylation of unreactive hindered alcohols as well as acid-sensitive alcohols. The reactions proceed in high yields using an acid anhydride, and 1a can be regenerated in a single step. The relative rates for benzoylation of (±)-menthol in C6D6 using conventional acylation reagents and strong nonionic bases are compared. In general, acetylation with 1a is accelerated in the polar solvent CH3CN whereas benzoylation is faster in the nonpolar solvent C6H6. The benzoylation intermediate RC(O)P(MeNCH2CH2)3N+ was found to be in equilibrium with 1a, with lower temperatures favoring the intermediate. The relative stabilities of several known acylating intermediates are compared.
- D'Sa, Bosco A.,Verkade, John G.
-
-
Read Online
- Novel and efficient method for esterification catalyzed by 1-glycyl-3-methyl imidazolium chloride-iron (III) complex
-
1-Glycyl-3-methyl imidazolium chloride-iron (III) complex [[Gmim]Cl-Fe(III)] was found to be a heterogeneous catalyst for an efficient and greener solvent free synthesis of esters by the condensation of carboxylic acids and alcohols with excellent yield at ambient temperature. This operation formulates very interesting, ecological perspective due to simple reaction condition, isolation, and purification of products. In addition, this method features reusability of catalyst, reduced waste, thus making new protocol more environmentally suitable whilst no catalyst leaching was observed. Iranian Chemical Society 2012.
- Karthikeyan, Parasuraman,Bhagat, Pundlik Rambhau,Kumar, Sellappan Senthil,Muskawar, Prashant Narayan,Aswar, Sachin Arunrao
-
-
Read Online
- Lanthanoid-Catalyzed Aldehyde Dimerization and Its Application to Polyester Synthesis
-
A wide variety of aldehydes are efficiently dimerized to esters by a catalytic amount of (C5Me5)2LnCH(SiMe3)2 (Ln=Nd, La).The reaction is applicable to the synthesis of polyesters from dialdehydes.A stoichiometric reaction of the lanthanum complex with benzaldehyde indicates the intermediacy of alkoxo complexes in the catalysis.
- Onozawa, Shun-ya,Sakakura, Toshiyasu,Tanaka, Masato
-
-
Read Online
- Synthesis of Pyrazines and Quinoxalines via Acceptorless Dehydrogenative Coupling Routes Catalyzed by Manganese Pincer Complexes
-
Base-metal catalyzed dehydrogenative self-coupling of 2-amino alcohols to selectively form functionalized 2,5-substituted pyrazine derivatives is presented. Also, 2-substituted quinoxaline derivatives are synthesized by dehydrogenative coupling of 1,2-diaminobenzene and 1,2-diols. In both cases, water and hydrogen gas are formed as the sole byproducts. The reactions are catalyzed by acridine-based pincer complexes of earth-abundant manganese.
- Daw, Prosenjit,Kumar, Amit,Espinosa-Jalapa, Noel Angel,Diskin-Posner, Yael,Ben-David, Yehoshoa,Milstein, David
-
-
Read Online
- Ruthenium complexes featuring cooperative phosphine-pyridine-iminophosphorane (PNN) ligands: Synthesis, reactivity and catalytic activity
-
The coordination to ruthenium(ii) centres of two phosphine-pyridine-iminophosphorane ligands LR (PPh2CH2(C6H3N)CH2NPR3, R = Ph or Cy) differing by the nature of the substituent of the PN phosphorus was explored. Coordination to [RuCl2(PPh3)3] afforded the complexes [RuLRCl2(PPh3)] that were successfully deprotonated at the acidic phosphinomethyl position. With LCy, coordination led to a mixture of two isomers. The complexes [RuLRHCl(PPh3)] were similarly obtained from [RuHCl(PPh3)3]. The stability of these complexes depends on the ligand substitution pattern; with LPh a CH activation process took place, while [RuLCyHCl(PPh3)] was thermally stable. Deprotonation of this latter complex was achieved and gave a catalytically competent species for the acceptorless dehydrogenative coupling of alcohols.
- Cheisson, Thibault,Mazaud, Louis,Auffrant, Audrey
-
-
Read Online
- Benzylation of carboxylic acids by oxidation-reduction condensation using quinones and benzyloxydiphenylphosphine
-
Various carboxylic benzyl esters were obtained in high yields by way of oxidation-reduction condensation in which benzyloxydiphenylphosphine (BDPP), having been prepared easily from chlorodiphenylphosphine and benzyl alcohol, was treated with various carboxylic acids in the presence of 2,6-dimethyl-1,4-benzoquinone(DMBQ) under mild conditions.
- Mukaiyama, Teruaki,Shintou, Taichi,Kikuchi, Wataru
-
-
Read Online
- Montmorillonite K10 and KSF clays as acidic and green catalysts for effective esterification of phenols and alcohols under MWI
-
Montmorillonite K-10 and KSF clays catalyze esterification of phenols and alcohols under microwave irradiation and solvent-free conditions in high yields within seconds.
- Marvi,Fekri,Takhti
-
-
Read Online
- Silver nanoparticles stabilized by a metal-organic framework (MIL-101(Cr)) as an efficient catalyst for imine production from the dehydrogenative coupling of alcohols and amines
-
In this paper, we present silver nanoparticles supported on a metal-organic framework (Ag@MIL-101) as a catalyst for the one-pot tandem synthesis of imines from alcohols and amines. The Ag@MIL-101 catalyst was fabricated using the liquid phase impregnation technique as an easy and effective method. The morphology and chemical structure of the prepared catalyst were systemically evaluated by inductively coupled plasma optical emission spectroscopy (ICP-OES), powder X-ray diffraction (P-XRD), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). The highly crystalline feature of the Ag metal nanoparticles on bifunctional MIL-101(Cr) was revealed by TEM and HRTEM analyses. The Ag@MIL-101 catalyst was examined as a catalyst for the synthesis of different imine derivatives. The catalytic performance of the Ag@MIL-101 catalyst was monitored by GC-MS and 1H-NMR analyses for the dehydrogenative coupling of alcohols and amines. Furthermore, the effect of various factors such as the amount of catalyst, base, temperature and solvent was investigated to optimize the conditions for the best performance of the Ag@MIL-101 catalyst. Catalytic activity test results showed that the Ag@MIL-101 catalyst has a good catalytic activity with TOF values in the range of 12.7-14.6 h-1 in the synthesis of various imines.
- Gumus, Ilkay,Karata?, Yas?r,Gülcan, Mehmet
-
-
Read Online
- Unprecedented reductive esterification of carboxylic acids under hydrogen by reusable heterogeneous platinum catalysts
-
Supported metal catalysts have been tested for an unprecedented reductive dimerization of carboxylic acids to esters under 8 bar hydrogen in solvent-free conditions. Among various metal-loaded tin oxide catalysts, platinum-loaded tin dioxide (Pt/SnO2) shows the highest ester yield for the reaction of dodecanoic acid. Among Pt catalysts on various supports, Lewis acidic oxides, especially SnO2, show high activity. The most active catalyst, 5 wt% Pt/SnO2 reduced at 100°C, is effective for the reductive esterification of various carboxylic acids, and the catalyst is reusable for nine cycles, demonstrating the first successful example for the title reaction. Infrared (IR) studies of a model compound (formic acid) on some metal oxides indicate a strong Lewis acid-base interaction between SnO2 and the carbonyl oxygen. For Pt/SnO2 catalysts with different Pt particle sizes, the activity increases with decreasing size of Pt metal. A cooperative catalysis of the Pt metal nanoparticles and the Sn4+ Lewis acid sites is proposed.
- Touchy, Abeda S.,Kon, Kenichi,Onodera, Wataru,Shimizu, Ken-Ichi
-
-
Read Online
- PH-sensitive gold nanoparticle catalysts for the aerobic oxidation of alcohols
-
Gold nanoparticles (NPs) stabilized by carboxylate modified polyvinylpyrrolidone have been prepared and fully characterized. The gold NPs efficiently catalyze the aerobic oxidation of benzyl alcohol in water at ambient temperature and are easily separated from the reaction mixture by lowering the pH of the solution, causing the NPs to precipitate. The mechanism of the precipitation process has been studied. Due to the efficiency of this process, the NPs may be reused as catalysts by readjusting their pH.
- Yuan, Yuan,Yan, Ning,Dyson, Paul J.
-
-
Read Online
- Synthesis of Esters from Stable and Convenient Sulfoxonium Precursors under Catalyst- And Additive-Free Conditions
-
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
-
-
Read Online
- Tributylphosphine-catalyzed acylation of alcohol by active ester directed toward effective end-capping of pseudorotaxane consisting of ammonium group and crown ether
-
According to the results of a model study using benzyl alcohol, pseudorotaxane with terminal hydroxy group on the axle was acylated with S-2-pyridyl 3,5-dimethylthiobenzoate in the presence of tributylphosphine to produce rotaxane in 85% yield. Optically
- Kihara, Nobuhiro,Nakakoji, Naohisa,Takata, Toshikazu
-
-
Read Online
- Surprisingly high sensitivity of copper nanoparticles toward coordinating ligands: Consequences for the hydride reduction of benzaldehyde
-
Functionalized copper nanoparticles are widely used as catalysts; however, identification of the catalytically active species remains a challenge. In this study we investigate hydride-assisted reduction reactions with special focus on the structural evolution of copper nanoparticles in the presence of phosphine and nitrogen-based ligands. These compounds are commonly used as stabilizing agents, and therefore are important in the context of other catalytic reactions as well. In particular, we investigate the case of tri-n-butylphosphine. Our findings show that ultrasmall nano-objects are formed as key intermediates to produce catalytically active species in the hydrosilylation of benzaldehyde into the corresponding silyl alcohol. Moreover, we found that the strength of the hydride donor is essential for the formation of the active catalysts. Therefore, this work unveils the previously overlooked high sensitivity of copper nanoparticles toward coordinating ligands in the context of catalysis.
- Frogneux, Xavier,Borondics, Ferenc,Lefran?ois, Stéphane,D'Accriscio, Florian,Sanchez, Clément,Carenco, Sophie
-
-
Read Online
- 2(3H)-BENZOXAZOLETHIONE.
-
A new condensing agent, N,N prime -carbonyldi left bracket 2(3H)-benzoxazolethione right bracket , was readily prepared by the reaction of 2-benzoxazolethiol and trichloromethyl chloroformate in benzene. The condensing agent is shown to be useful for the preparation of amides, esters, and dipeptides under mild conditions. A successful polyamide synthesis by the polycondensation of isophthalic acid with diamines using the condensing agent is also described.
- Ueda,Kawaharasaki,Imai
-
-
Read Online
- Solution phase synthesis of esters within a micro reactor
-
A range of techniques are demonstrated for the solution phase synthesis of esters within an EOF-based borosilicate glass micro reactor, including the use of mixed anhydrides and the in situ preparation of acyl halides.
- Wiles, Charlotte,Watts, Paul,Haswell, Stephen J.,Pombo-Villar, Esteban
-
-
Read Online
- CeO2 as a versatile and reusable catalyst for transesterification of esters with alcohols under solvent-free conditions
-
CeO2 acted as an efficient and reusable heterogeneous catalyst for transesterification of esters with alcohols under the solvent-free conditions at 160 °C. Among the 11 kinds of metal oxides, CeO2 is the most suitable catalyst in terms of catalytic activity, leaching-resistance and reusability. This catalytic system tolerates various esters and alcohols, and valuable esters such as heteroaromatic esters and benzyl benzoates are produced, demonstrating a practical utility of the system. On the basis of kinetic analysis and in situ IR studies of adsorbed species, a reaction mechanism is proposed, in which proton abstraction of alcohol by a Lewis base site of CeO2 to yield alkoxide species is the rate-limiting step.
- Tamura, Masazumi,Hakim Siddiki,Shimizu, Ken-Ichi
-
-
Read Online
- Synthesis and coordination chemistry of tridentate (PNN) amine enamido phosphine ligands with ruthenium
-
Tridentate amine-imine-phosphine ligands, R2PC5H7NC2H4NEt2 [RPNN(H)], where R = Pri or But are synthesized using a straightforward protocol of condensation, deprotonation, and addition of a chlorodialkylphosphine. Multinuclear NMR spectroscopy shows the ligands exist exclusively in the enamine tautomeric form in solution. Treating these ligands with RuHCl(PPri3)2(CO) forms the desired coordination compounds, RuHCl[RPNN(H)](CO), where the imine tautomeric form of the ligands coordinates to ruthenium. Deuterium labelling experiments show Ru-H/N-D scrambling occurs during ligand coordination. Treating the RuHCl[RPNN(H)](CO) precursors with potassium tert-butoxide allows for the synthesis of two new ruthenium enamido-phosphine complexes, RuH[RPNN](CO), which were fully characterized. The structure of one of the derivatives was confirmed by X-ray crystallography (R = Pri). The reactivity of the enamido-phosphine complexes with H2 and benzyl alcohol is also reported. For the enamido phosphine complex where R = Pri, the reaction with H2 is reversible and forms (RuH(CO)[PriPNN(H)])2(μ-H)2, a hydride-bridged dimer that results from cooperative activation of H2. The reactivity of both amine-enamido-phosphine ruthenium compounds with benzyl alcohol establishes that the complexes are catalyst precursors for acceptorless dehydrogenation (AD), although the turnover frequencies measured using both catalyst precursors are modest.
- Wambach,Lenczyk,Patrick,Fryzuk
-
-
Read Online
- Oxidation of benzyl ethers via phase transfer catalysis
-
A convenient procedure for the oxidation of benzyl ethers to benzoate esters is reported. Potassium permanganate in dichloromethane with phase transfer catalysis by triethylbenzylammonium chloride (TEBAC) affords products regiospecifically in fair to excellent yields.
- Markgraf, J. Hodge,Choi, Bo Yoon
-
-
Read Online
- Synthesis and reactivity of ruthenium complexes bearing arsenic-containing arsenic-nitrogen-arsenic-type pincer ligand
-
Dinuclear and mononuclear ruthenium complexes bearing an arsenic-containing arsenic-nitrogen-arsenic (ANA)-type pincer ligand are designed, prepared, and characterized by X-ray analyses. Both ruthenium complexes work as effective catalysts toward dehydrogenative transformations of alcohols.
- Tanabe, Yoshiaki,Kuriyama, Shogo,Arashiba, Kazuya,Nakajima, Kazunari,Nishibayashi, Yoshiaki
-
-
Read Online
- Mechanochemical Palladium-Catalyzed Carbonylative Reactions Using Mo(CO)6
-
Esters and amides were mechanochemically prepared by palladium-catalyzed carbonylative reactions of aryl iodides by using molybdenum hexacarbonyl as a convenient solid carbonyl source and avoiding a direct handling of gaseous carbon monoxide. Real-time monitoring of the mechanochemical reaction by in situ pressure sensing revealed that CO is rapidly transferred from Mo(CO)6 to the active catalytic system without significant release of molecular carbon monoxide.
- van Bonn, Pit,Bolm, Carsten,Hernández, José G.
-
-
Read Online
- Imidazolium ionic liquid-supported sulfonic acids: Efficient and recyclable catalysts for esterification of benzoic acid
-
Several imidazolium ionic liquid (IL)-supported sulfonic acids with different anions, [C3SO3Hmim]HSO4, [C 3SO3Hmim]BF4, [C3SO 3Hmim]PF6, and [C3SO3Hmim]CF 3SO3, were synthesized and applied as catalysts for esterification reaction of benzoic acid. The experimental results indicate that imidazolium IL-supported sulfonic acid containing anion of HSO4 - shows the best catalytic activity. Only when less [C 3SO3Hmim]HSO4 (0.3 equiv.) applied, was the product obtained with high yield of 97%. Furthermore, the produced esters could be separated by decantation, and the catalyst could be reused after the removal of water.
- Cai, Yue Qin,Yu, Guo Qiang,Liu, Chuan Duo,Xu, Yuan Yuan,Wang, Wei
-
-
Read Online
- Isopropoxyaluminum 1,1′-biphenyl-2-oxy-2′-perfluorooctanesulfonamide as a catalyst for Tishchenko reaction
-
Isopropoxyaluminum 1,1′-biphenyl-2-oxy-2′-perfluorooctanesulfonamide (3) has been evaluated as an aluminum-based catalyst for the Tishchenko reaction. Compound 3 was found to exert high catalytic activity in the reaction with aliphatic aldehydes and also enabled smooth dimerization of enolizable aldehydes. This advantage was highlighted by the quantitative formation of ethyl acetate from acetaldehyde by the present system.
- Ooi, Takashi,Ohmatsu, Kohsuke,Sasaki, Kouji,Miura, Tomoya,Maruoka, Keiji
-
-
Read Online
- Synthesis of aromatic esters catalyzed by palladium on charcoal: An efficient heterogeneous catalyst for alkoxycarbonylation of aryl iodides
-
Palladium on charcoal was found to catalyze the carbonylation of aryl iodides with various aliphatic alcohols as well as less reactive phenols to give the corresponding esters in high yield at 140°C and in the presence of carbon monoxide (1.0 MPa). The carbonylation-polycondensation of 2,7-diiodo-9,10-dihydrophenanthrene with bisphenol-A afforded high molecular weight polyarylate, poly [oxy-1,4-phenylene (1-methylethylidene)-1,4-phenyleneoxycarbonyl (9,10-dihydro-2,7-phenanthrenediyl) carbonyl].
- Ramesh, Chinnasamy,Nakamura, Ryo,Kubota, Yoshihiro,Miwa, Minoru,Sugi, Yoshihiro
-
-
Read Online
- Transesterification of methylbenzoate with alcohols catalyzed by natural phosphate
-
Transesterification of methylbenzoate with various alcohols was catalyzed by natural phosphate with or without solvent in heterogeneous media. The molar ratio of alcohol/ester, solvent effect, and weight of catalyst effect have been studied. We have found that the nature of alcohol and the reaction temperature play an important role in the transesterification process. The catalyst can be regenerated and reused without lost of activity. Copyright Taylor & Francis Group, LLC.
- Bazi, Fathallaah,El Badaoui, Hanane,Sokori, Samira,Tamani, Soumia,Hamza, Mohamed,Boulaajaj, Said,Sebti, Said
-
-
Read Online
- Efficient acceptorless dehydrogenation of secondary alcohols to ketones mediated by a PNN-Ru(II) catalyst
-
Four types of ruthenium(II) complexes, [fac-PNN]RuH(PPh3)(CO) (A), [fac-PNHN]RuH(η1-BH4)(CO) (B), [fac-PNHN]RuCl2(PPh3) (C) and [fac-PNHN]RuH(η1-BH4)(PPh3) (D) (where PNHN and PNN are N-(2-(diphenylphosphino)ethyl)-5,6,7,8-tetrahydroquinoline-8-amine and its deprotonated derivative), have been synthesized and assessed as catalysts for the acceptorless dehydrogenation of secondary alcohols to afford ketones. It was found that C, in combination with t-BuOK, proved the most effective and versatile catalyst allowing aromatic-, aliphatic- and cycloalkyl-containing alcohols to be efficiently converted to their corresponding ketones with particularly high values of TON achievable. Furthermore, the mechanism for this PNN-Ru mediated process been proposed on the basis of a number of intermediates that have been characterized by EI-MS and NMR spectroscopy. These catalysts show great potential for applications in atom-economic synthesis as well as in the development of organic hydride-based hydrogen storage systems.
- Wang, Zheng,Pan, Bing,Liu, Qingbin,Yue, Erlin,Solan, Gregory A.,Ma, Yanping,Sun, Wen-Hua
-
-
Read Online
- Acceptorless dehydrogenative coupling of primary alcohols to esters by heterogeneous Pt catalysts
-
Supported platinum catalysts have been studied for the acceptor-free dehydrogenative coupling of primary alcohols to esters in the liquid phase under solvent-free conditions in N2at 180 °C. The activity depends on the support material, and Pt-loaded SnO2(Pt/SnO2) gives the highest activity. Pt/SnO2shows higher activity than various transition metals (Ir, Re, Ru, Rh, Pd, Ag, Co, Ni, Cu) loaded on SnO2. The Pt/SnO2catalyst (1 mol%) selectively converted various primary alcohols to their corresponding esters in moderate to high isolated yield (53-91%). This is the first example of reusable heterogeneous catalysts for the acceptor-free dehydrogenative coupling of primary alcohols to esters under additive-free and solvent-free conditions. Mechanistic and infrared (IR) studies are also shown to discuss the reaction pathway and a possible role of the SnO2support as Lewis acid sites that activate carbonyl groups of adsorbed aldehyde intermediates.
- Moromi, Sondomoyee Konika,Hakim Siddiki,Ali, Md. Ayub,Kon, Kenichi,Shimizu, Ken-Ichi
-
-
Read Online
- Bicyclic guanidinate compounds of magnesium and their activity as pre-catalysts in the Tishchenko reaction
-
A synthetic route to magnesium guanidinate compounds that avoids ligand redistribution is reported; selected derivatives are active pre-catalysts in the dimerization of aldehydes.
- Day, Benjamin M.,Mansfield, Natalie E.,Coles, Martyn P.,Hitchcock, Peter B.
-
-
Read Online
- An expedient esterification of aromatic carboxylic acids using sodium bromate and sodium hydrogen sulfite
-
Treatment of aromatic carboxylic acids and substituted toluenes with a mixture of sodium bromate and sodium hydrogen sulfite in a two-phase system gave the corresponding esters in good yield. The intermediate α-brominated toluene was formed by the in situ generated hypobromous acid. The α-bromotoluene underwent an intermolecular nucleophilic substitution reaction with aromatic carboxylic acids present in the reaction mixture to afford the corresponding esters.
- Khan, Khalid Mohammed,Maharvi, Ghulam Murtaza,Hayat, Safdar,Zia-Ullah,Choudhary, M. Iqbal,Atta-ur-Rahman
-
-
Read Online
- Copper Tetrasulfophthalocyanine Intercalated Hydrotalcite as an Efficient Bifunctional Catalyst for the Baeyer–Villiger Oxidation
-
Abstract: A heterogeneous bifunctional hybrid catalyst originated from copper tetrasulfophthalocyanine (CuPcTs) and hydrotalcite for Baeyer–Villiger (B-V) oxidation has been prepared and characterized. XRD, FTIR, DR UV-Vis and SEM characterization indicate that CuPcTs molecule has been successfully intercalated into the layer of ZnAl hydrotalcite. And the synthesized hybrid exhibited excellent catalytic activity in the B-V oxidation for various ketones under mild conditions. Its bifunctional role in the reaction through O2/benzaldehyde has been discussed and verified by controlled experiments. The study indicates that the designed catalyst not only catalyzes the oxidation of benzaldehyde to perbenzoic acid, but also accelerates the transformation of ketone to lactone or ester. Graphical Abstract: [Figure not available: see fulltext.]
- Zhou, Weiyou,Chen, Yong,Qian, Junfeng,Sun, Fu’an,He, Mingyang,Chen, Qun
-
-
Read Online
- Alkali-metal organomagnesiate complexes as catalysts for highly chemoselective crossed-Tishchenko reactions
-
Five new heterobimetallic magnesiates bearing bidentate dianionic pyrrolyl ligands have been synthesized through co-complexation with alkali-metal reagents and di-n-butylmagnesium. Single-crystal X-ray structural analysis of these complexes revealed a variety of intriguing bonding modes. These alkali-metal (Li, Na, and K) organomagnesiates were utilized as catalysts for cross-coupling Tishchenko reactions with two different aldehydes. The sodium alkyl magnesiate complex {nBuMg[2-(Me3CNCH2)C4H3N]Na(Et2O)}8(3) was identified as a competent catalyst, as it exhibited higher catalytic activities and chemoselectivity under mild conditions.
- Guo, Zhiqiang,Pang, Tengfei,Wang, Yakong,Zhang, Yongbin,Wei, Xuehong
-
-
Read Online
- Mono(imidazolin-2-iminato) actinide complexes: Synthesis and application in the catalytic dimerization of aldehydes
-
The synthesis of the mono(imidazolin-2-iminato) actinide(IV) complexes [(ImRN)An(N{SiMe3)2}3] (3-8) was accomplished by the protonolysis reaction between the respective imidazolin-2-imine (ImRNH, R = tBu, Mes, Dipp) and the actinide metallacycles [{(Me3Si)N}2An{κ2C,N-CH2SiMe2N(SiMe3)}] (1, An = U; 2, M = Th). The thorium and uranium complexes were obtained in high yields, and their structures were established by single-crystal X-ray diffraction analysis. The mono(imidazolin-2-iminato) actinide complexes 3-8 display short An-N bonds together with large An-N-C angles, indicating strong electron donation from the imidazolin-2-iminato moiety to the metal, corroborating a substantial π-character to the An-N bond. The reactivity of complexes 3-8 toward benzaldehyde was studied in the catalytic dimerization of aldehydes (Tishchenko reaction), displaying low to moderate catalytic activities for the uranium complexes 3-5 and moderate to high catalytic activities for the thorium analogues 6-8, among which 8 exhibited the highest catalytic activity. In addition, actinide coordination compounds showed unprecedented reactivity toward cyclic and branched aliphatic aldehydes in the catalytic Tishchenko reaction mediated by the thorium complex [(ImDippN)Th{N(SiMe3)2}3] (8), exhibiting high activity even at room temperature. Moreover, complex 8 was successfully applied in the crossed Tishchenko reaction between an aromatic or polyaromatic and an aliphatic cyclic and branched aldehyde, yielding selectively the asymmetrically substituted ester in high yields (80-100%).
- Karmel, Isabell S. R.,Fridman, Natalia,Tamm, Matthias,Eisen, Moris S.
-
-
Read Online
- Synthesis of Ruthenium Complexes Bearing PCP-Type Pincer Ligands and Their Application to Direct Synthesis of Imines from Amines and Benzyl Alcohol
-
Ruthenium complexes bearing N-heterocyclic carbene- and phosphine-based PCP-type pincer ligands are synthesized and characterized by X-ray crystallography. The ruthenium-PCP complexes have catalytic activity toward direct synthesis of imines from reactions of amines and benzyl alcohol. The lifetime of the ruthenium complex bearing the PCP pincer ligand is longer than that of the ruthenium complex bearing a pyridine-based PNP-type pincer ligand.
- Eizawa, Aya,Nishimura, Shunsuke,Arashiba, Kazuya,Nakajima, Kazunari,Nishibayashi, Yoshiaki
-
-
Read Online
- Organoactinides promote the Tishchenko reaction: The myth of inactive actinide-alkoxo complexes
-
For many decades, compounds containing oxygen atoms were excluded from the actinide-catalysis field because of the high oxophilic nature of these complexes. Pursuing the conceptual question about the potential activity of actinide-oxo bonds we were surprised to find that the coupling of aromatic aldehydes catalyzed by Cp*2ThMe2 and Th(NEtMe)4 via thorium-alkoxide intermediates takes place in high yields to produce the corresponding esters. In this paper we present our breakthrough results including comprehensive mechanistic, deuterium labeling, kinetic, and thermodynamic studies. A plausible mechanism is presented taking into account as well the thermochemistry of the process. Copyright
- Andrea, Tamer,Barnea, Eyal,Eisen, Moris S.
-
-
Read Online
- Zr(IV)-Fe(III), -Ga(III), and -Sn(IV) binary metal complexes as synergistic and reusable esterification catalysts
-
Synergism in catalytic activity with the combined use of Hf(O-i-Pr) 4 or Zr(O-i-Pr)4 and Fe(O-i-Pr)3 for direct esterification and a very simple method for their extraction with ionic liquids for their recovery and reuse are described. This Zr(IV)-Fe(III) complex is an environmentally benign catalyst due to its high turnover number, extremely mild Lewis acidity, low toxicity, reusability, and commercial availability at low cost.
- Sato, Atsushi,Nakamura, Yuka,Maki, Toshikatsu,Ishihara, Kazuaki,Yamamoto, Hisashi
-
-
Read Online
- Metal-catalyzed acyl transfer reactions of enol esters: Role of Y5(OiPr)13O and (thd)2Y(OiPr) as transesterification catalysts
-
(equation presented) Primary and secondary alcohols react with vinyl or isopropenyl acetate at room temperature in the presence of catalytic amounts (0.05-1 mol percent) of Y5(OiPr)13O to give the corresponding esters. In selected cases, the yttrium catalyst promotes the selective O-acylation of amino alcohols without the formation of the amide. Enol esters also react with α-amino acid esters in the absence of a catalyst, at room temperature, to give the corresponding amides.
- Lin, Mei-Huey,RajanBabu
-
-
Read Online
- The Direct Alkylation of π-Rich, Acid-Sensitive Heterocyclic Compounds via Essentially Free Carbocations
-
Alkylation of π-rich heteroaromatics such as pyrroles and furans by the standard Friedel-Crafts approach is impractical because the acid catalysts employed (Bronsted or Lewis) induce polyalkylation, ring opening, and polymerization. The present study describes the facile benzylation of π-excessive heteroaromatics using the nitrosoamide approach, which generates nitrogen-separated carbocation-counterion ion-pairs as the alkylating agent with no catalyst being required. N-Nitrosoamides are favorable sources of carbocations because of the following variables: mildness of the conditions required to generate cations, high reactivity of the unsolvated carbocations formed, solubility of the precursors in a wide range of solvents, homogeneity of the reactions, wide range of decomposition temperatures possible, straightforward chemistry, and excellent product balance. The majority of the cations that are generated in pyrrole (80%) are intercepted by the solvent, and only 20% are intercepted by the counterion; this result provides support for the intermediacy of nitrogen-separated ion-pairs in deamination. A nucleophilicity scale is presented for reactions of selected nucleophiles with essentially free carbocations.
- Darbeau, Ron W.,White, Emil H.
-
-
Read Online
- Au?Pd Selectivity-switchable Alcohol-oxidation Catalyst: Controlling the Duality of the Mechanism using a Multivariate Approach
-
Supported gold-palladium nanoparticles are highly selective catalysts for the oxidation of alcohols. However, little is known about how integrated reaction conditions can affect the chemoselectivity of a specific catalytic system. Herein, a novel Au?Pd selectivity-switchable catalyst supported on SrCO3 is reported; and a multivariate optimization was suggested as the key process to better understand the formation of the products. The optimization approach considered temperature, pressure, time of reaction, and Au : Pd molar ratio, and settled that the temperature and Au : Pd molar ratio showed an important effect on the ester yield, while just the metal molar ratio significantly influenced the selectivity for the aldehyde. Thus, taking into consideration the experimental data and optimized conditions, we were able to efficiently switch the selectivity by just changing the pressure of the system in a benzyl alcohol oxidation reaction. In addition, we proposed that the presence of O2 implies that there are two catalytic pathways, which leads to different selectivity, allowing us to bring some mechanistic insights dealing with the duality of the mechanism. Such outcomes are based on dense experimental results and characterizations (FT-IR, Rietveld refinement, XPS, H2-TPR, and EDS-STEM). The catalyst was also very stable, presenting activity up to 6 runs without loss of activity and selectivity, under certain reaction conditions.
- da S. Melo, Itaciara E. M.,de Sousa, Samuel A. A.,dos S. Pereira, Laíse N.,Oliveira, Jefferson M.,Castro, Karla P. R.,Costa, Jean C. S.,de Moura, Edmilson M.,de Moura, Carla V. R.,Garcia, Marco A. S.
-
-
Read Online
- Catalytic bond forming reactions promoted by amidinate, guanidinate and phosphaguanidinate compounds of magnesium
-
The synthesis and catalytic properties of a series of magnesium compounds consisting of monoanionic, N,N'-chelating ligands (N∩N = amidinates, guanidinates, phosphaguanidinates) is reported. The compounds were synthesized by (i) insertion of a carbodiimide into an existing Mg-C or Mg-N bond, or (ii) protonolysis of an organomagnesium compound by a neutral pre-ligand. Structural analyses of mono- or bis-(chelate) compounds with general formula Mg(N∩N)X(L)nand Mg(N∩N)2(L)n(X = halide, aryloxide, amide; L = Et2O, THF; n = 0, 1 or 2) have been performed and the influence that the ligand substituent patterns have on the solid-state structures has been probed. Selected examples of the compounds were tested as (pre)catalysts for the polymerization of lactide, the dimerization of aldehydes and the hydroacetylenation of carbodiimides.
- Schwamm, Ryan J.,Coles, Martyn P.,Day, Benjamin M.,Mansfield, Natalie E.,Knowelden, William,Hitchcock, Peter B.
-
-
Read Online
- Imidazol(in)ium-2-carboxylates as latent, thermally activated organocatalysts for transesterification reactions
-
1,3-Disubstituted imidazol(in)ium-2-carboxylates (ImCO2) were used as precatalysts for transesterification reactions of unactivated ethyl benzoate with monohydric alcohols, dihydric alcohols, and amino alcohols. Highly active N-heterocyclic carbenes (NHCs) are usually not used directly as catalysts because of their air and moisture sensitivity. Here they were liberated in situ by thermal decarboxylation of ImCO2 at designated temperatures. The results showed that the yield of the reactions reached up to 95 within 3 h using only 0.5 mol catalyst. No active enol esters, molecular sieves, or a 20-fold excess of alcohol were used to drive the reaction to completion. It was proved that unsaturated imidazolium-2-carboxylates have a better activity than saturated species in this type of reaction. Different types of substituting groups of ImCO2 exhibited varied transesterification activity.
- Wang, Yanqin,Li, Zhenjiang
-
-
Read Online
- Pentacarbonylmethylmanganese(i) as a synthon for Mn(i) pincer catalysts
-
Mn(i) complexes that enable metal-ligand cooperative substrate activation catalyze a range of transformations. Use of MeMn(CO)5 as a synthon in place of typical Mn(CO)5Br was explored and found to be quite versatile, generating catalytically active species in situ by activation of O-H, N-H, and even C-H bonds.
- Kadassery, Karthika J.,Lacy, David C.
-
-
Read Online
- Easy, Green and Safe Carbonylation Reactions through Zeolite-Catalyzed Carbon Monoxide Production from Formic Acid
-
Zeolites with the right shape and acid site density and strength, such as certain ZSM-5 forms, were able to cleanly decompose formic acid to carbon monoxide (CO), and the latter could be directly used in palladium-catalyzed carbonylation reactions. A simple two-reactor system was designed to produce CO conveniently and then further react this gas in a safe way. The two-reactor system is particularly cheap, easy to set up and use. In addition, the carbonylation conditions without pressure allowed for very efficient CO incorporation, with only 1% of palladium(II) chloride (PdCl2) and Xantphos.
- Losch, Pit,Felten, Anne-Sophie,Pale, Patrick
-
-
Read Online
- One-step solvent-free aerobic oxidation of aliphatic alcohols to esters using a tandem Sc-Ru?MOF catalyst
-
Esters are an important class of chemicals in industry. Traditionally, ester production is a multi-step process involving the use of corrosive acids or acid derivatives (e.g. acid chloride, anhydride, etc.). Therefore, the development of a green synthetic protocol is highly desirable. This work reports the development of a metal-organic framework (MOF) supported tandem catalyst that can achieve direct alcohol to ester conversion (DAEC) using oxygen as the sole oxidizing agent under strictly solvent-free conditions. By incorporating Ru nanoparticles (NPs) along with a homogeneous Lewis acid catalyst, scandium triflate, into the nanocavities of a Zr MOF, MOF-808, the compound catalyst, Sc-Ru?MOF-808, can achieve aliphatic alcohol conversion up to 92% with ester selectivity up to 91%. A mechanistic study reveals a unique “via acetal” pathway in which the alcohol is first oxidized on Ru NPs and rapidly converted to an acetal on Sc(iii) sites. Then, the acetal slowly decomposes to release an aldehyde in a controlled manner for subsequent oxidation and esterification to the ester product. To the best of our knowledge, this is the first example of DAEC of aliphatic alcohols under solvent-free conditions with high conversion and ester selectivity.
- Feng, Tingkai,Li, Conger,Li, Tao,Zhang, Songwei
-
supporting information
p. 1474 - 1480
(2022/03/08)
-
- ZWITTERIONIC CATALYSTS FOR (TRANS)ESTERIFICATION: APPLICATION IN FLUOROINDOLE-DERIVATIVES AND BIODIESEL SYNTHESIS
-
An amide/iminium zwitterion catalyst has a catalyst pocket size that promotes transesterification and dehydrative esterification. The amide/iminium zwitterions are easily prepared by reacting aziridines with aminopyridines. The reaction can be applied a wide variety of esterification processes including the large-scale synthesis of biodiesel. The amide/iminium zwitterions allow the avoidance of strongly basic or acidic condition and avoidance of metal contamination in the products. Reactions are carried out at ambient or only modestly elevated temperatures. The amide/iminium zwitterion catalyst is easily recycled and reactions proceed in high to quantitative yields.
- -
-
Paragraph 0015; 0028
(2021/01/29)
-
- Disproportionation of aliphatic and aromatic aldehydes through Cannizzaro, Tishchenko, and Meerwein–Ponndorf–Verley reactions
-
Disproportionation of aldehydes through Cannizzaro, Tishchenko, and Meerwein–Ponndorf–Verley reactions often requires the application of high temperatures, equimolar or excess quantities of strong bases, and is mostly limited to the aldehydes with no CH2 or CH3 adjacent to the carbonyl group. Herein, we developed an efficient, mild, and multifunctional catalytic system consisting AlCl3/Et3N in CH2Cl2, that can selectively convert a wide range of not only aliphatic, but also aromatic aldehydes to the corresponding alcohols, acids, and dimerized esters at room temperature, and in high yields, without formation of the side products that are generally observed. We have also shown that higher AlCl3 content favors the reaction towards Cannizzaro reaction, yet lower content favors Tishchenko reaction. Moreover, the presence of hydride donor alcohols in the reaction mixture completely directs the reaction towards the Meerwein–Ponndorf–Verley reaction. Graphic abstract: [Figure not available: see fulltext.].
- Sharifi, Sina,Sharifi, Hannah,Koza, Darrell,Aminkhani, Ali
-
p. 803 - 808
(2021/07/20)
-
- Sodium organoaluminate containing bidentate pyrrolyl ligand: Synthesis, structure, and catalytic activity for the Tishchenko reaction
-
An novel sodium organoaluminate containing bidentate pyrrolyl ligand [C4H3NH(2-CH2NHtBu)] was efficiently synthesized and characterized by X-ray crystallography. The molecular structure shows it is a monodimensional infinite chain structures with linear arrangements. Its basic repeat unit comprises the Al atom bonded to two deprotonated pyrrole rings and Na atom coordinated to of nitrogen atoms of –NtBu fragment, which undergoes further to coordinates a pyrrolyl ring of an adjacent molecule in a ?2-fasion. Furthermore, this sodium organoaluminate exhibited high catalytic activities for Tishchenko reaction.
- Liu, Yu,Guo, Zhiqiang,Wang, Yakong
-
-
- Photochemical Activation of Aromatic Aldehydes: Synthesis of Amides, Hydroxamic Acids and Esters
-
A cheap, facile and metal-free photochemical protocol for the activation of aromatic aldehydes has been developed. Utilizing thioxanthen-9-one as the photocatalyst and cheap household lamps as the light source, a variety of aromatic aldehydes have been activated and subsequently converted in a one-pot reaction into amides, hydroxamic acids and esters in good to high yields. The applicability of this method was highlighted in the synthesis of Moclobemide, a drug against depression and social anxiety. Extended and detailed mechanistic studies have been conducted, in order to determine a plausible mechanism for the reaction.
- Nikitas, Nikolaos F.,Apostolopoulou, Mary K.,Skolia, Elpida,Tsoukaki, Anna,Kokotos, Christoforos G.
-
p. 7915 - 7922
(2021/05/03)
-
- Metal-Free Selective Modification of Secondary Amides: Application in Late-Stage Diversification of Peptides
-
Here we solve a long-standing challenge of the site-selective modification of secondary amides and present a simple two-step, metal-free approach to selectively modify a particular secondary amide in molecules containing multiple primary and secondary amides. Density functional theory (DFT) provides insight into the activation of C-N bonds. This study encompasses distinct chemical advances for late-stage modification of peptides thus harnessing the amides for the incorporation of various functional groups into natural and synthetic molecules.
- Adebomi, Victor,Sriram, Mahesh,Streety, Xavier,Raj, Monika
-
p. 6189 - 6193
(2021/08/01)
-
- Electrodimerization ofN-Alkoxyamides for the Synthesis of Hydrazines
-
An efficient and valuable N-N dimerization reaction ofN-alkoxyamides is reported under undivided electrolytic conditions. This electrochemical strategy provides a powerful way to access a wide range of advanced, highly functionalized hydrazines. Remarkably, anN-centered radical generated from the cleavage of the N-H bond under electrolytic conditions plays a crucial role in this transformation. Furthermore, variousN-alkoxyamides bearing different substituents are suitable in this transformation, furnishing the corresponding hydrazines in up to 92% yield.
- Nasier, Abudulajiang,Chang, Xihao,Guo, Chang
-
p. 16068 - 16076
(2021/09/18)
-
- Selective aerobic oxidation of toluene to benzaldehyde catalyzed by covalently anchored N-hydroxyphthalimide and cobaltous ions
-
Selective oxidation of toluene to benzaldehyde via dioxygen is of great significance industrially but suffers from a severely low selectivity due to a much higher reactivity of the desired product than the reactant. A combination of homogeneous N-hydroxyphthalimide (NHPI) and cobaltous ions was found active and selective for the transformation from toluene to benzaldehyde in the presence of hexafloropropan-2-ol. In this work, homogeneous NHPI was covalently anchored onto the surface of commercial mesoporous SiO2 to facilitate the separation and recovery of the catalyst, aiming at a possible industrial application. The grafting bonds were well confirmed by FT-IR, TGA and XP spectra, and the density of > N–OH groups anchored was up to 0.6 mmol/g in the immobilized NHPI catalysts. The resulting catalysts exhibited an excellent activity for selective oxidation of toluene to benzaldehyde, and there was no appreciable loss in catalytic activity observed after repeated evaluations, suggesting a promising prospect for its further investigation and possible application.
- Xu, Jinyang,Shi, Guojun,Liang, Yuxin,Lu, Qiuting,Ji, Lijun
-
-
- Discriminating non-ylidic carbon-sulfur bond cleavages of sulfonium ylides for alkylation and arylation reactions
-
A sulfonium ylide participated alkylation and arylation under transition-metal free conditions is described. The disparate reaction pattern allowed the separate activation of non-ylidic S-alkyl and S-aryl bond. Under acidic conditions, sulfonium ylides serve as alkyl cation precursors which facilitate the alkylations. While under alkaline conditions, cleavage of non-ylidic S-aryl bond produces O-arylated compounds efficiently. The robustness of the protocols were established by the excellent compatibility of wide variety of substrates including carbohydrates.
- Cai, Lei,Chen, Qi,Fang, Jing,Li, Ting,Liao, Zhiwen,Ma, Xiang,Meng, Lingkui,Sun, Jiuchang,Wan, Qian,Zeng, Jing
-
-
- Direct Amidation of Esters by Ball Milling**
-
The direct mechanochemical amidation of esters by ball milling is described. The operationally simple procedure requires an ester, an amine, and substoichiometric KOtBu and was used to prepare a large and diverse library of 78 amide structures with modest to excellent efficiency. Heteroaromatic and heterocyclic components are specifically shown to be amenable to this mechanochemical protocol. This direct synthesis platform has been applied to the synthesis of active pharmaceutical ingredients (APIs) and agrochemicals as well as the gram-scale synthesis of an active pharmaceutical, all in the absence of a reaction solvent.
- Barreteau, Fabien,Battilocchio, Claudio,Browne, Duncan L.,Godineau, Edouard,Leitch, Jamie A.,Nicholson, William I.,Payne, Riley,Priestley, Ian
-
supporting information
p. 21868 - 21874
(2021/09/02)
-
- PCl3-mediated transesterification and aminolysis of tert-butyl esters via acid chloride formation
-
A PCl3-mediated conversion of tert-butyl esters into esters and amides in one-pot under air is developed. This novel protocol is highlighted by the synthesis of skeletons of bioactive molecules and gram-scale reactions. Mechanistic studies revealed that this transformation involves the formation of an acid chloride in situ, which is followed by reactions with alcohols or amines to afford the desired products.
- Wu, Xiaofang,Zhou, Lei,Li, Fangshao,Xiao, Jing
-
p. 491 - 497
(2021/01/20)
-
- Benzyne-Mediated Esterification Reaction
-
A benzyne-mediated esterification of carboxylic acids and alcohols under mild conditions has been realized, which is made possible via a selective nucleophilic addition of carboxylic acid to benzyne in the presence of alcohol. After a subsequent transesterification with alcohol, the corresponding esters can be produced efficiently. This benzyne-mediated protocol can be used on the modification of Ibuprofen, cholesterol, estradiol, and synthesis of nandrolone phenylpropionate. In addition, benzyne can also be used to promote lactonization and amidation reaction.
- Li, Yang,Shi, Jiarong,Zhao, Jinlong
-
supporting information
p. 7274 - 7278
(2021/10/01)
-
- A solvent-reagent selection guide for Steglich-type esterification of carboxylic acids
-
The Steglich esterification is a widely employed method for the formation of esters under mild conditions. A number of issues regarding the sustainability of this transformation have been identified, chiefly the use of hazardous carbodiimide coupling reagents in conjunction with solvents with considerable issues such as dichloromethane (DCM) and N,N-dimethylformamide (DMF). To overcome these issues, we have developed a solvent-reagent selection guide for the formation of esters via Steglich-type reactions with the aim of providing safer, more sustainable conditions. Optimum reaction conditions have been identified after high-throughput screening of solvent-reagent combinations, namely the use of Mukaiyama's reagent (Muk) in conjunction with solvent dimethyl carbonate (DMC). The new reaction conditions were also exemplified through the synthesis of a small selection of building-block like molecules and includes the formation of t-butyl esters.
- Jordan, Andrew,Sneddon, Helen F.,Sydenham, Jack,Whymark, Kyran D.
-
supporting information
p. 6405 - 6413
(2021/09/10)
-
- Carboxylic Acid Reductase Can Catalyze Ester Synthesis in Aqueous Environments
-
Most of the well-known enzymes catalyzing esterification require the minimization of water or activated substrates for activity. This work reports a new reaction catalyzed by carboxylic acid reductase (CAR), an enzyme known to transform a broad spectrum of carboxylic acids into aldehydes, with the use of ATP, Mg2+, and NADPH as co-substrates. When NADPH was replaced by a nucleophilic alcohol, CAR from Mycobacterium marinum can catalyze esterification under aqueous conditions at room temperature. Addition of imidazole, especially at pH 10.0, significantly enhanced ester production. In comparison to other esterification enzymes such as acyltransferase and lipase, CAR gave higher esterification yields in direct esterification under aqueous conditions. The scalability of CAR catalyzed esterification was demonstrated for the synthesis of cinoxate, an active ingredient in sunscreen. The CAR esterification offers a new method for green esterification under high water content conditions.
- Pongpamorn, Pornkanok,Kiattisewee, Cholpisit,Kittipanukul, Narongyot,Jaroensuk, Juthamas,Trisrivirat, Duangthip,Maenpuen, Somchart,Chaiyen, Pimchai
-
supporting information
p. 5749 - 5753
(2021/02/01)
-
- Development of effective bidentate diphosphine ligands of ruthenium catalysts toward practical hydrogenation of carboxylic acids
-
Hydrogenation of carboxylic acids (CAs) to alcohols represents one of the most ideal reduction methods for utilizing abundant CAs as alternative carbon and energy sources. However, systematic studies on the effects of metal-to-ligand relationships on the catalytic activity of metal complex catalysts are scarce. We previously demonstrated a rational methodology for CA hydrogenation, in which CA-derived cationic metal carboxylate [(PP)M(OCOR)]+ (M = Ru and Re; P = one P coordination) served as the catalyst prototype for CA self-induced CA hydrogenation. Herein, we report systematic trial- and-error studies on how we could achieve higher catalytic activity by modifying the structure of bidentate diphosphine (PP) ligands of molecular Ru catalysts. Carbon chains connecting two P atoms as well as Ar groups substituted on the P atoms of PP ligands were intensively varied, and the induction of active Ru catalysts from precatalyst Ru(acac)3 was surveyed extensively. As a result, the activity and durability of the (PP)Ru catalyst substantially increased compared to those of other molecular Ru catalyst systems, including our original Ru catalysts. The results validate our approach for improving the catalyst performance, which would benefit further advancement of CA self-induced CA hydrogenation.
- Saito, Susumu,Wen, Ke,Yoshioka, Shota
-
p. 1510 - 1524
(2021/06/18)
-
- Oxidative esterification of alcohols by a single-side organically decorated Anderson-type chrome-based catalyst
-
The direct esterification of alcohols with non-noble metal-based catalytic systems faces great challenges. Here, we report a new chrome-based catalyst stabilized by a single pentaerythritol decorated Anderson-type polyoxometalate, [N(C4H9)4]3[CrMo6O18(OH)3C{(OCH2)3CH2OH}], which can realize the efficient transformation from alcohols to esters by H2O2oxidation in good yields and high selectivity without extra organic ligands. A variety of alcohols with different functionalities including some natural products and pharmaceutical intermediates are tolerated in this system. The chrome-based catalyst can be recycled several times and still keep the original configuration and catalytic activity. We also propose a reasonable catalytic mechanism and prove the potential for industrial applications.
- Wang, Jingjing,Jiang, Feng,Tao, Chaofu,Yu, Han,Ruhlmann, Laurent,Wei, Yongge
-
supporting information
p. 2652 - 2657
(2021/04/21)
-
- Dehydrogenative alcohol coupling and one-pot cross metathesis/dehydrogenative coupling reactions of alcohols using Hoveyda-Grubbs catalysts
-
In this study,in situformed ruthenium hydride species that were generated from Grubbs type catalysts are used as efficient catalysts for dehydrogenative alcohol coupling and sequential cross-metathesis/dehydrogenative coupling reactions. The selectivity of Grubbs first generation catalysts (G1) in dehydrogenative alcohol coupling reactions can be tuned for the ester formation in the presence of weak bases, while the selectivity can be switched to the β-alkylated alcohol formation using strong bases. The performance of Hoveyda-Grubbs 2nd generation catalyst (HG2) was improved in the presence of tricyclohexylphosphine for the selective synthesis of ester derivatives with weak and strong bases in quantitative yields. Allyl alcohol was used as self and cross-metathesis substrate for the HG2 catalyzed sequential cross-metathesis/dehydrogenative alcohol coupling reactions to obtain γ-butyrolactone and long-chain ester derivatives in quantitative yields.
- ?zer, Halenur,Arslan, Dilan,?ztürk, Bengi ?zgün
-
p. 5992 - 6000
(2021/04/12)
-
- A rutheniumcis-dihydride with 2-phosphinophosphinine ligands catalyses the acceptorless dehydrogenation of benzyl alcohol
-
The first ruthenium dihydride complex featuring a phosphinine ligandcis-[Ru(H)2(2-PPh2-3-Me-6-SiMe3-PC5H2)2] was synthesised exclusively as thecis-isomer. When formedin situfrom the reaction ofcis-[Ru(Cl)2(2-PPh2-3-Me-6-SiMe3-PC5H2)2] with two equivalents of Na[BHEt3], as demonstrated by31P and1H NMR spectroscopy, the catalysed acceptorless dehydrogenation of benzyl alcohol was observed leading to benzyl benzoate in up to 70% yield.
- Andresen, John M.,Delve, Matthew P.,Luz, Christian,Mansell, Stephen M.,Newland, Robert J.,Trodden, Elizabeth C.
-
supporting information
p. 13407 - 13411
(2021/10/12)
-
- A novel two-dimensional metal-organic framework as a recyclable heterogeneous catalyst for the dehydrogenative oxidation of alcohol and theN-arylation of azole compounds
-
A novel metal-organic framework (MOF) with two-dimensional (2D) crystal structure was developed using Cu(NO3)2·3H2O and 2,2′,5,5′-tetramethoxy-[1,1′-biphenyl]-4,4′-dicarboxylic acid. Further, its structure was characterized using infrared spectroscopy, thermogravimetry, X-ray diffraction, and X-ray crystallography. The activated Cu-MOF was used to catalyze the dehydrogenative oxidation of alcohol andN-arylation of azole compounds. Furthermore, it could be easily recovered and reused.
- Liu, Chengxin,Cui, Jin,Wang, Yufang,Zhang, Mingjie
-
p. 11739 - 11744
(2021/03/31)
-
- Azolium Control of the Osmium-Promoted Aromatic C-H Bond Activation in 1,3-Disubstituted Substrates
-
The hexahydride complex OsH6(PiPr3)2 promotes the C-H bond activation of the 1,3-disubstituted phenyl group of the [BF4]- and [BPh4]- salts of the cations 1-(3-(isoquinolin-1-yl)phenyl)-3-methylimidazolium and 1-(3-(isoquinolin-1-yl)phenyl)-3-methylbenzimidazolium. The reactions selectively afford neutral and cationic trihydride-osmium(IV) derivatives bearing κ2-C,N- or κ2-C,C-chelating ligands, a cationic dihydride-osmium(IV) complex stabilized by a κ3-C,C,N-pincer group, and a bimetallic hexahydride formed by two trihydride-osmium(IV) fragments. The metal centers of the hexahydride are separated by a bridging ligand, composed of κ2-C,N- and κ2-C,C-chelating moieties, which allows electronic communication between the metal centers. The wide variety of obtained compounds and the high selectivity observed in their formation is a consequence of the main role of the azolium group during the activation and of the existence of significant differences in behavior between the azolium groups. The azolium role is governed by the anion of the salt, whereas the azolium behavior depends upon its imidazolium or benzimidazolium nature. While [BF4]- inhibits the azolium reactions, [BPh4]- favors the azolium participation in the activation process. In contrast to benzimidazolylidene, the imidazolylidene resulting from the deprotonation of the imidazolium substituent coordinates in an abnormal fashion to direct the phenyl C-H bond activation to the 2-position. The hydride ligands of the cationic dihydride-osmium(IV) pincer complex display intense quantum mechanical exchange coupling. Furthermore, this salt is a red phosphorescent emitter upon photoexcitation and displays a noticeable catalytic activity for the dehydrogenation of 1-phenylethanol to acetophenone and of 1,2-phenylenedimethanol to 1-isobenzofuranone. The bimetallic hexahydride shows catalytic synergism between the metals, in the dehydrogenation of 1,2,3,4-tetrahydroisoquinoline and alcohols.
- Cancela, Lara,Esteruelas, Miguel A.,Oliván, Montserrat,O?ate, Enrique
-
p. 3979 - 3991
(2021/12/02)
-
- Dual utility of a single diphosphine-ruthenium complex: A precursor for new complexes and, a pre-catalyst for transfer-hydrogenation and Oppenauer oxidation
-
The diphosphine-ruthenium complex, [Ru(dppbz)(CO)2Cl2] (dppbz = 1,2-bis(diphenylphosphino)benzene), where the two carbonyls are mutually cis and the two chlorides are trans, has been found to serve as an efficient precursor for the synthesis of new complexes. In [Ru(dppbz)(CO)2Cl2] one of the two carbonyls undergoes facile displacement by neutral monodentate ligands (L) to afford complexes of the type [Ru(dppbz)(CO)(L)Cl2] (L = acetonitrile, 4-picoline and dimethyl sulfoxide). Both the carbonyls in [Ru(dppbz)(CO)2Cl2] are displaced on reaction with another equivalent of dppbz to afford [Ru(dppbz)2Cl2]. The two carbonyls and the two chlorides in [Ru(dppbz)(CO)2Cl2] could be displaced together by chelating mono-anionic bidentate ligands, viz. anions derived from 8-hydroxyquinoline (Hq) and 2-picolinic acid (Hpic) via loss of a proton, to afford the mixed-tris complexes [Ru(dppbz)(q)2] and [Ru(dppbz)(pic)2], respectively. The molecular structures of four selected complexes, viz. [Ru(dppbz)(CO)(dmso)Cl2], [Ru(dppbz)2Cl2], [Ru(dppbz)(q)2] and [Ru(dppbz)(pic)2], have been determined by X-ray crystallography. In dichloromethane solution, all the complexes show intense absorptions in the visible and ultraviolet regions. Cyclic voltammetry on the complexes shows redox responses within 0.71 to -1.24 V vs. SCE. [Ru(dppbz)(CO)2Cl2] has been found to serve as an excellent pre-catalyst for catalytic transfer-hydrogenation and Oppenauer oxidation.
- Mukherjee, Aparajita,Bhattacharya, Samaresh
-
p. 15617 - 15631
(2021/05/19)
-
- Base-Free Benzyl Alcohol Aerobic Oxidation Catalyzed by AuPdNPs Supported on SBA-15 and TiO2/SBA-15 Mesoporous Materials
-
It is known that the oxidative reactions of alcohols are sensitive to the characteristics of the catalyst, in such a way that the properties of the support are as important as those of the metallic phase. We consider the functionalization of support as a
- Costa, Jean Cláudio S.,Luz, Geraldo E.,Magalh?es, Janildo Lopes,Sousa, Renilma Carvalho,da Silva, Jussara Morais,de Moura, Carla Veronica Rodarte,de Moura, Edmilson Miranda
-
-
- Palladium-catalyzed synthesis of α-aryl acetophenones from styryl ethers and aryl diazonium saltsviaregioselective Heck arylation at room temperature
-
Preparation of α-aryl acetophenones from styryl ethers and aryldiazonium salts is described. The reaction is catalyzed by palladium acetate at room temperature in the absence of ligand and base. The developed method is highly attractive in terms of reaction conditions, substrate scope, functional group tolerance and yields. Synthetic applications of the present method are demonstrated by preparing α-aryl indoles and 3-aryl isocoumarin from styryl ethers.
- Kandasamy, Jeyakumar,Lee, Yong Rok,Singh, Adesh Kumar,Venkatesh, Rapelly
-
supporting information
p. 7832 - 7837
(2021/09/28)
-
- Lipase catalysed oxidations in a sugar-derived natural deep eutectic solvent
-
Chemoenzymatic oxidations involving the CAL-B/H2O2 system was developed in a sugar derived Natural Deep Eutectic Solvent (NaDES) composed by a mixture of glucose, fructose and sucrose. Good to excellent conversions of substrates like cyclooctene, limonene, oleic acid and stilbene to their corresponding epoxides, cyclohexanone to its corresponding lactone and 2-phenylacetophenone to its corresponding ester, demonstrate the viability of the sugar NaDES as a reaction medium for epoxidation and Baeyer-Villiger oxidation.
- Vagnoni, Martina,Samorì, Chiara,Pirini, Daniele,Vasquez De Paz, Maria Katrina,Gidey, Dawit Gebremichael,Galletti, Paola
-
-
- A facile and versatile electro-reductive system for hydrodefunctionalization under ambient conditions
-
A general electrochemical system for reductive hydrodefunctionalization is described, employing the inexpensive and easily available triethylamine (Et3N) as a sacrificial reductant. This protocol is characterized by facile operation, sustainable conditions, and exceptionally wide substrate scope covering the cleavage of C-halogen, N-S, N-C, O-S, O-C, C-C and C-N bonds. Notably, the selectivity and capability of reduction can be conveniently switched by simple incorporation or removal of an alcohol as a co-solvent.
- Huang, Binbin,Guo, Lin,Xia, Wujiong
-
p. 2095 - 2103
(2021/03/26)
-
- Hydrogen-bond-assisted transition-metal-free catalytic transformation of amides to esters
-
The amide C-N cleavage has drawn a broad interest in synthetic chemistry, biological process and pharmaceutical industry. Transition-metal, luxury ligand or excess base were always vital to the transformation. Here, we developed a transition-metal-free hydrogen-bond-assisted esterification of amides with only catalytic amount of base. The proposed crucial role of hydrogen bonding for assisting esterification was supported by control experiments, density functional theory (DFT) calculations and kinetic studies. Besides broad substrate scopes and excellent functional groups tolerance, this base-catalyzed protocol complements the conventional transition-metal-catalyzed esterification of amides and provides a new pathway to catalytic cleavage of amide C-N bonds for organic synthesis and pharmaceutical industry. [Figure not available: see fulltext.]
- Huang, Changyu,Li, Jinpeng,Wang, Jiaquan,Zheng, Qingshu,Li, Zhenhua,Tu, Tao
-
-
- Iodine-catalyzed synthesis of β-uramino crotonic esters as well as oxidative esterification of carboxylic acids in choline chloride/urea: a desirable alternative to organic solvents
-
Abstract: Iodine-mediated selective synthesis of β-uramino crotonic esters was achieved via the reaction of β-dicarbonyls and urea at room temperature. Choline chloride/urea mixture, as an eco-friendly, cheap, non-toxic, and recyclable deep eutectic solvent (DES), was employed as sustainable media as well as reagent at the same time in these transformations. Some derivatives of β-uramino crotonic esters were synthesized with good to high yields without a tedious work-up. The process could be done to synthesize the above-mentioned compounds in gram scale. Moreover, oxidative cross-esterification of carboxylic acids with alkyl benzenes was carried out in the above-mentioned DES by the employment of tetrabutylammonium iodide (TBAI) as the catalyst and tert-butyl hydroperoxide (TBHP) as the oxidant at 80?°C. DES/TBAI system was reused up to five consecutive times. Graphic abstract: Iodine-catalyzed C–N and C–O bond formation in choline chloride/urea as a green solvent under the mild reaction conditions. Providing the clean procedure toward synthesis of β-uramino crotonic esters and benzylic esters.[Figure not available: see fulltext.].
- Moayyed, Mohammadesmaeil,Saberi, Dariush
-
p. 445 - 455
(2020/09/07)
-
- A Bifunctional Copper Catalyst Enables Ester Reduction with H2: Expanding the Reactivity Space of Nucleophilic Copper Hydrides
-
Employing a bifunctional catalyst based on a copper(I)/NHC complex and a guanidine organocatalyst, catalytic ester reductions to alcohols with H2 as terminal reducing agent are facilitated. The approach taken here enables the simultaneous activation of esters through hydrogen bonding and formation of nucleophilic copper(I) hydrides from H2, resulting in a catalytic hydride transfer to esters. The reduction step is further facilitated by a proton shuttle mediated by the guanidinium subunit. This bifunctional approach to ester reductions for the first time shifts the reactivity of generally considered "soft"copper(I) hydrides to previously unreactive "hard"ester electrophiles and paves the way for a replacement of stoichiometric reducing agents by a catalyst and H2.
- Kaicharla, Trinadh,Ngoc, Trung Tran,Teichert, Johannes F.,Tzaras, Dimitrios-Ioannis,Zimmermann, Birte M.
-
supporting information
p. 16865 - 16873
(2021/10/20)
-
- N-Aroylbenzotriazoles as Efficient Reagents for o-Aroylation in Absence of Organic Solvent
-
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
-
p. 2671 - 2674
(2021/10/25)
-
- Electrochemical phenothiazination of naphthylamines and its application in photocatalysis
-
N-Phenylphenothiazine as an inexpensive, highly reductive and oxygen tolerant organophotocatalyst has exhibited potential in various challenging photochemical transformations. Here we report a general and straightforward method to access structurally diverse N-phenylphenothiazine derivatives by means of a novel electrochemical tool. The introduction of a 2-naphthylamine moiety with an extended π-system and an amine group led to the variation of spectral characterization. Photochemical verification experiments demonstrated that the formed N-arylation products with good efficacy and chemo/site-control displayed competitive catalytic activity in challenging transformations. This journal is
- Chen, Song,Li, Ya-Nan,Xiang, Shao-Hua,Li, Shaoyu,Tan, Bin
-
supporting information
p. 8512 - 8515
(2021/08/31)
-
- Carboxyboronate as a Versatile In Situ CO Surrogate in Palladium-Catalyzed Carbonylative Transformations
-
The application of carboxy-MIDA-boronate (MIDA=N-methyliminodiacetic acid) as an in situ CO surrogate for various palladium-catalyzed transformations is described. Carboxy-MIDA-boronate was previously shown to be a bench-stable boron-containing building block for the synthesis of borylated heterocycles. The present study demonstrates that, in addition to its utility as a precursor to heterocycle synthesis, carboxy-MIDA-boronate is an excellent in situ CO surrogate that is tolerant of reactive functionalities such as amines, alcohols, and carbon-based nucleophiles. Its wide functional-group compatibility is highlighted in the palladium-catalyzed aminocarbonylation, alkoxycarbonylation, carbonylative Sonogashira coupling, and carbonylative Suzuki–Miyaura coupling of aryl halides. A variety of amides, esters, (hetero)aromatic ynones, and bis(hetero)aryl ketones were synthesized in good-to-excellent yields in a one-pot fashion.
- Tien, Chieh-Hung,Trofimova, Alina,Holownia, Aleksandra,Kwak, Branden S.,Larson, Reed T.,Yudin, Andrei K.
-
supporting information
p. 4342 - 4349
(2020/12/25)
-
- Dehydrogenative amide synthesis from alcohols and amines utilizing N-heterocyclic carbene-based ruthenium complexes as efficient catalysts: The influence of catalyst loadings, ancillary and added ligands
-
The metal-catalyzed dehydrogenative coupling of alcohols and amines to access amides has been recognized as an atom-economic and environmental-friendly process. Apart from the formation of the amide products, three other kinds of compounds (esters, imines and amines) may also be produced. Therefore, it is of vital importance to investigate product distribution in this transformation. Herein, N-heterocyclic carbene-based Ru (NHC/Ru) complexes [Ru-1]-[Ru-5] with different ancillary ligands were prepared and characterized. Based on these complexes, we selected condition A (without an added NHC precursor) and condition B (with an added NHC precursor) to comprehensively explore the selectivity and yield of the desired amides. After careful evaluation of various parameters, the Ru loadings, added NHC precursors and the electronic/steric properties of ancillary NHC ligands were found to have considerable influence on this catalytic process.
- Wang, Wan-Qiang,Wang, Zhi-Qin,Sang, Wei,Zhang, Rui,Cheng, Hua,Chen, Cheng,Peng, Da-Yong
-
-
- Synthesis of chloroesters by the reaction of ethers with acyl chlorides catalyzed by ZnO
-
An efficient method for the synthesis of chloroesters by the reaction of ethers with acyl chlorides catalyzed by nano-ZnO under solvent-free condition at room temperature was described. The method is compatible with a range of ethers including tricyclic ethers, tetracyclic ethers, pentacyclic ethers and hexacyclic ethers and have afforded the products with moderate to good yields. The ZnO could be reused up to three times and the product yield after three cycles is 87%.
- Tang, Yuqi,Feng, Chengliang,Yang, Wanfeng,Ji, Min,Wang, Wei,Chen, Junqing
-
-
- N-Heterocyclic Carbene Catalyzed Ester Synthesis from Organic Halides through Incorporation of Oxygen Atoms from Air
-
Oxygenation reactions with molecular oxygen (O2) as the oxygen source provides a green and straightforward strategy for the construction of O-containing compounds. Demonstrated here is a novel N-heterocyclic carbene (NHC) catalyzed oxidative transformation of simple and readily available organic halides into valuable esters through the incorporation of O-atoms from O2. Mechanistic studies prove that the deoxy Breslow intermediate generated in situ is oxidized to a Breslow intermediate for further transformation by this oxidative protocol. This method broadens the field of NHC catalysis and promotes oxygenation reactions with O2.
- Tan, Hui,Wang, Shen-An,Yan, Zixi,Liu, Jianzhong,Wei, Jialiang,Song, Song,Jiao, Ning
-
supporting information
p. 2140 - 2144
(2020/12/01)
-
- Solar and visible-light active nano Ni/g-C3N4photocatalyst for carbon monoxide (CO) and ligand-free carbonylation reactions
-
In this study, we investigate the amino and alkoxycarbonylation reaction between various substituted aryl halides, benzyl iodides, and iodocyclohexane with different types of amines and alcohols in the absence of carbon monoxide gas and ligands. Similar reactions are carried out at high temperatures, in the presence of appropriate ligands, stoichiometric amounts of bases, and gaseous carbon monoxide, which endanger the health of organic chemists. We present a novel method that does not utilize ligands, bases, gaseous CO, and special conditions. This procedure is a redox reaction carried out by new economic nano Ni/g-C3N4at room temperature and under visible light. Mo(CO)6was used toin situgenerate CO, to resolve the problems caused by the use of CO gas. This protocol has the ability to be used on a gram scale by using a continuous flow reactor.
- Hosseini-Sarvari, Mona,Akrami, Zahra
-
p. 956 - 969
(2021/02/26)
-
- Zr-MOF-808 as Catalyst for Amide Esterification
-
In this work, zirconium-based metal–organic framework Zr-MOF-808-P has been found to be an efficient and versatile catalyst for amide esterification. Comparing with previously reported homogeneous and heterogeneous catalysts, Zr-MOF-808-P can promote the reaction for a wide range of primary, secondary and tertiary amides with n-butanol as nucleophilic agent. Different alcohols have been employed in amide esterification with quantitative yields. Moreover, the catalyst acts as a heterogeneous catalyst and could be reused for at least five consecutive cycles. The amide esterification mechanism has been studied on the Zr-MOF-808 at molecular level by in situ FTIR spectroscopic technique and kinetic study.
- Villoria-del-álamo, Beatriz,Rojas-Buzo, Sergio,García-García, Pilar,Corma, Avelino
-
supporting information
p. 4588 - 4598
(2020/12/25)
-
- Magnesium hydrides bearing sterically demanding amidinate ligands: synthesis, reactivity and catalytic application
-
The synthesis and characterisation of a series of magnesium complexes bearing sterically demanding amidinate ligands is reported; this includes magneisum amides (1a and 1b), hydrides (3a and 3b) and alkyl complexes (2b). The solid and solution state behaviour of the complexes has been investigated using single crystal X-ray diffraction and NMR spectroscopy, revealing the magnesium hydrides to exist as dimers in the solid state, dispite the sterically demanding ligand systems and showing a degree of monomeric character in solution. The stoichiometric and catalytic activity of the amidinate complexes were investigated, with the complexes found to efficiently mediate both the hydroamination of N,N′-diisopropylcarbodiimide and the Tishchenko reaction. The metal hydrides are highly reactive towards coordinating substrates, showing a significant increase in catalytic rate compared with more ubiquitous β-diketiminate magnesium hydrides.
- Bakewell, Clare
-
supporting information
p. 11354 - 11360
(2020/09/02)
-
- Visible-light-induced selective aerobic oxidation of sp3 C-H bonds catalyzed by a heterogeneous AgI/BiVO4 catalyst
-
An efficient oxidation of sp3 C-H bonds to esters and ketones has been developed using AgI/BiVO4 as the photocatalyst and O2 as the oxidant in water. Various substrates can be transformed into the desired esters and ketones in moderate to good yields. The synthetic utility of this approach has been demonstrated by gram-level experiments and consecutive oxidation experiments. A plausible mechanism has been proposed.
- Jiang, Li-Ya,Ming, Jing-Jing,Wang, Lian-Yue,Jiang, Yuan-Yuan,Ren, Lan-Hui,Wang, Zi-Cheng,Cheng, Wen-Chen
-
supporting information
p. 1156 - 1163
(2020/03/11)
-
- Synthetic method of benzyl benzoate (by machine translation)
-
The invention discloses a synthetic method of benzyl benzoate. The synthesis method comprises the following steps: in a solvent, a nucleophilic substitution reaction of sodium benzoate and benzyl chloride in the presence of a quaternary ammonium salt; and the solvent is an alkane solvent and/or an ester solvent. In the synthetic method, benzyl chloride is high in conversion rate and low in impurity content, and the obtained benzyl benzoate crude product is high in purity, low in impurity content and low in color number. (by machine translation)
- -
-
Paragraph 0060-0123
(2020/09/30)
-
- Purification method of benzyl benzoate
-
The invention discloses a purification method of benzyl benzoate. The purification method comprises the following steps: mixing a benzyl benzoate crude product solution with a benzyl benzoate seed crystal, and carrying out solid-liquid separation to obtain a solid, namely benzyl benzoate. The benzyl benzoate crude product solution consists of a benzyl benzoate crude product and a solvent; the solvent is isopropanol and water; the mass ratio of the benzyl benzoate crude product to the solvent is 2: (1.4-4.0); the mass ratio of the isopropanol to the water is 2: (0.5-1.2); the temperature of thebenzyl benzoate crude product solution before mixing is 5-15 DEG C; and the mixing temperature is 5-15 DEG C. The purification method of benzyl benzoate is high in yield, and the obtained product ishigh in purity, low in color number value, low in impurity content and convenient for industrial production.
- -
-
Paragraph 0081-0131; 0137-0153; 0156; 0166-0169
(2020/09/09)
-
- Reaction Cycling for Kinetic Analysis in Flow
-
A reactor capable of efficiently collecting kinetic data in flow is presented. Conversion over time data is obtained by cycling a discrete reaction slug back and forth between two residence coils, with analysis performed each time the solution is passed between the two. In contrast to a traditional steady-state continuous flow system, which requires upward of 5× the total reaction time to obtain reaction progress data, this design achieves much higher efficiency by collecting all data during a single reaction. In combination with minimal material consumption (reactions performed in 300 μL slugs), this represents an improvement in efficiency for typical kinetic experimentation in batch as well. Application to kinetic analysis of a wide variety of transformations (acylation, SNAr, silylation, solvolysis, Pd catalyzed C-S cross-coupling and cycloadditions) is demonstrated, highlighting both the versatility of the reactor and the benefits of performing kinetic analysis as a routine part of reaction optimization/development. Extension to the monitoring of multiple reactions simultaneously is also realized by operating the reactor with multiple reaction slugs at the same time.
- Newman, Stephen G.,Sullivan, Ryan J.
-
supporting information
p. 5464 - 5474
(2020/05/19)
-
- Synthesis of Some Aromatic and Aliphatic Esters Using WO3/ZrO2 Solid Acid Catalyst under Solvent Free Conditions
-
A simple method is delineated for the synthesis of substituted ester products in superior yields by esterification reaction under solvent unbound condition using tungsten upgraded ZrO2 solid acid catalyst at 353 K. The WO3/ZrO2 catalyst has been prepared by using impregnation method followed by calcination at 923 K over a period of 6 h in air atmosphere. SEM, XRD, FTIR, and BET surface area techniques were used to categorize this catalyst. Zirconia has both acidic and basic possessions which can be changed by incorporating suitable promoter atom like tungsten which in turn increases the surface area thereby enhancing the surface acidity. Impregnation of W6+ ions exhibits a strong influence on phase modification of zirconia from thermodynamically solid monoclinic to metastable tetragonal phase. Amalgamation of promoter W6+ will stabilize tetragonal phase which is active in catalyzing reactions. In esterification reaction WO3/ZrO2 catalyst was found to be stable, efficient and environmental friendly, effortlessly recovered by filtration, excellent yield of product and can be reusable efficiently.
- Guguloth, Vijaya Charan,Battu, Satyanarayana
-
p. 2153 - 2157
(2020/09/16)
-
- Catalytic C-H Bond Oxidation Using Dioxygen by Analogues of Heme Superoxide
-
Heme active sites are capable of oxidizing organic substrates by four electrons using molecular oxygen (heme dioxygenases), where a dioxygen (O2) adduct of heme (FeIII-O2-) acts as the primary oxidant, in contrast to monooxygenases, where high-valent species are involved. This chemistry, although lucrative, is difficult to access using homogeneous synthetic systems. Over the past few years using a combination of self-assembly and in situ resonance Raman spectroscopy, the distribution of different reactive intermediates formed during the electrochemical reduction of oxygen has been elucidated. An FeIII-O2- species, which is the reactive species of dioxygenase, is an intermediate in heterogeneous electrochemical O2 reduction by iron porphyrins and its population, under electrochemical conditions, may be controlled by controlling the applied potential. Iron porphyrins having different axial ligands are constructed on a self-assembled monolayer of thiols on an electrode, and these constructs can activate O2 and efficiently catalyze the dioxygenation of 3-methylindole and oxidation of a series of organic compounds having C-H bond energies between 80 and 90 kcal mol-1 at potentials where FeIII-O2- species are formed on the electrode. Isotope effects suggest that hydrogen-atom transfer from the substrate is likely to be the rate-determining step. Axial thiolate ligands are found to be more efficient than axial imidazoles or phenolates with turnover numbers above 60000 and turnover frequencies over 60 s-1. These results highlight a new reaction engineering approach to harness O2 as a green oxidant for efficient chemical oxidation.
- Dey, Abhishek,Mukherjee, Manjistha
-
p. 7415 - 7425
(2020/06/17)
-
- Metal complex catalysts and method for catalytically reducing carboxylic acids
-
The invention relates to a metal complex catalyst, which contains at least one of metal complexes with a chemical formula comprising a structural unit represented by a formula I. According to the invention, the center metal of the metal complex catalyst is iridium, and the metal complex catalyst is composed of pentamethylcyclopentadienyl, a bitetrahydropyrimidine ligand and proper coordination anions; the metal complex catalyst has activity on a carboxylic acid reduction reaction, and a carboxylic acid compound is reduced into an alcohol compound in the presence of hydrogen; and the method ismild in reaction condition, can be carried out at room temperature, and is good in catalytic performance and high in reduction product yield.
- -
-
Paragraph 0169; 0170
(2020/06/20)
-
- 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
-
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
-
p. 1655 - 1664
(2020/01/31)
-
- A robust NNP-type ruthenium (II) complex for alcohols dehydrogenation to esters and pyrroles
-
A Ru (II) complex bearing pyridyl-based benzimidazole-phosphine tridentate NNP ligand was synthesized and structurally characterized by NMR, IR. The complex can efficiently and selectively catalyze the acceptorless dehydrogenation of primary alcohols to esters under relatively mild conditions and the synthesis of pyrroles by means of the reactions of secondary alcohols and β-amino alcohols through acceptorless deoxygenation condensation.
- Chai, Huining,Zhang, Guangyao,Tan, Weiqiang,Ma, Jiping
-
-
- Thermally regulated molybdate-based ionic liquids toward molecular oxygen activation for one-pot oxidative cascade catalysis
-
One-pot oxidative cascade catalysis plays a central role in the synthesis of key pharmaceutical and industrial molecules. Although ionic liquids are one of the most promising solvents and reaction media, the breakthrough of their catalysis in aerobic oxidation is very challenging due to the difficulty in the direct activation of molecular oxygen. Herein, a family of novel thermally regulated molybdate-based ionic liquids (Mo-ILs) has been designed and developed for the first time toward molecular oxygen activation for highly efficient tandem oxidative catalysis. Three diverse one-pot oxidative cascade processes for the syntheses of various flavones, imines, and benzyl benzoates were achieved with good to excellent yields using the Mo-IL [Bmim]2[MoO4] as a catalyst under air conditions. The results of spectroscopic investigations and quantum-chemical calculations further demonstrated that a thermally regulated proton migration between the cation [Bmim] and anion [MoO4] was the key to forming N-heterocyclic carbene and thereby to effortlessly promoting the generation of O2- active species from molecular oxygen, which results in excellent catalytic performance in these three aerobic tandem oxidations. Our work extends the application area of ILs as the sole catalyst to one-pot aerobic oxidative cascade catalysis, which could have pronounced implications in future work.
- Song, Zhibin,Huang, Wei,Zhou, Yan,Tian, Zi-Qi,Li, Zhang-Min,Tao, Duan-Jian
-
supporting information
p. 103 - 109
(2020/01/21)
-
- Non-metallic Aerobic Oxidation of Alcohols over Anthraquinone Based Compounds
-
The catalytic performances of substituted anthraquinones were investigated in catalytic oxidation of alcohols like cyclohexanol, benzyl alcohol and 5-hydroxymethylfurfural (HMF) to carbonyl compounds (cyclohexanone, benzyl aldehyde and diformylfuran). The reduction potential of anthraquinone plays the key role in the oxidation reactions. TOF numbers and selectivities to carbonyl compounds pass through the maximum with increase of the reduction potential. The maximum activity and selectivity (>80 %) is observed for sulfonated and carboxylated anthraquinones having intermediate reduction potentials (≈ 0.1-0.2 V vs SHE). Grafted 2-carboxyanthraquinone catalyst has demonstrated comparable catalytic performance to the parent molecule and might be used as heterogeneous catalyst. The oxidation reaction was found to have radical character with transfer of hydrogen from alcohol to anthraquinone and subsequent oxidation of hydrogenated anthraquinone by oxygen.
- Zhao, Jingpeng,Wu, Dan,Hernández, Willinton Yesid,Zhou, Wen-Juan,Capron, Mickael,Ordomsky, Vitaly V.
-
-
- Accessing Basic Sites on Modified CoFe2O4 Nanoparticles: Addressing the Selective Oxidation of Benzyl Alcohol and Unraveling the Au:Pd Ratio Effects by XPS
-
AuPd nanoparticles have gained substantial attention due to their application in selective oxidation of alcohols. However, due to the radical nature of the oxidation of benzyl alcohol, under specific conditions, even without a catalyst, the reaction occur
- Duarte, Alfredo,Garcia, Marco A. S.,Pereira, Laíse N. S.,Rozendo, Jennifer,Vidinha, Pedro,de Moura, Carla V. R.,de Moura, Edmilson M.
-
p. 1859 - 1872
(2020/10/09)
-
- Holey Lamellar High-Entropy Oxide as an Ultra-High-Activity Heterogeneous Catalyst for Solvent-free Aerobic Oxidation of Benzyl Alcohol
-
The development of noble-metal-free heterogeneous catalysts is promising for selective oxidation of aromatic alcohols; however, the relatively low conversion of non-noble metal catalysts under solvent-free atmospheric conditions hinders their industrial application. Now, a holey lamellar high entropy oxide (HEO) Co0.2Ni0.2Cu0.2Mg0.2Zn0.2O material with mesoporous structure is prepared by an anchoring and merging process. The HEO has ultra-high catalytic activity for the solvent-free aerobic oxidation of benzyl alcohol. Up to 98 % conversion can be achieved in only 2 h, to our knowledge, the highest conversion of benzyl alcohol by oxidation to date. By regulating the catalytic reaction parameters, benzoic acid or benzaldehyde can be selectively optimized as the main product. Analytical characterizations and calculations provide a deeper insight into the catalysis mechanism, revealing abundant oxygen vacancies and holey lamellar framework contribute to the ultra-high catalytic activity.
- Dai, Sheng,Dong, Yangbo,Feng, Danyang,Ge, Xin,Qiao, Zhen-An,Zhang, Liangliang,Zhang, Wei
-
supporting information
p. 19503 - 19509
(2020/07/04)
-