- Palladium nanoparticles, stabilized by lignin, as catalyst for cross-coupling reactions in water
-
Palladium nanoparticles of a definite shape (spherical) and dimension (8-14 and 16-20 nm) were prepared employing two water soluble lignin samples as both reducing and stabilizing agent in definitely green experimental conditions, namely aqueous solution, aerobic conditions, moderate temperature, short times. The above nanoparticles were employed as catalyst for a series of carbon-carbon coupling reactions carried out in water at mild conditions. Heck and Suzuki reactions were performed for several substrates, by changing the nature of halogen, the substituents at the aromatic ring, the bases employed and the temperature. Product yields were satisfactory and selectivities very good. Other two cross-coupling reactions, namely Sonogashira and Stille, were also tested: iodine derivatives showed always the best reactivity, while chlorine derivatives did not react.
- Coccia, Francesca,Tonucci, Lucia,D'Alessandro, Nicola,D'Ambrosio, Primiano,Bressan, Mario
-
-
Read Online
- Isopropenyl acetate: A cheap and general acylating agent of alcohols under metal-free conditions
-
Functionalized primary, secondary and tertiary alcohols are efficiently acetylated by isopropenyl acetate and catalytic p-TsOH.
- Temperini, Andrea,Minuti, Lucio,Morini, Tommaso,Rosati, Ornelio,Piazzolla, Francesca
-
-
Read Online
- Benzoquinone Cocatalyst Contributions to DAF/Pd(OAc)2-Catalyzed Aerobic Allylic Acetoxylation in the Absence and Presence of a Co(salophen) Cocatalyst
-
Palladium(II)-catalyzed allylic acetoxylation has been the focus of extensive development and investigation. Methods that use molecular oxygen (O2) as the terminal oxidant typically benefit from the use of benzoquinone (BQ) and a transition-metal (TM) cocatalyst, such as Co(salophen), to support oxidation of Pd0 during catalytic turnover. We previously showed that Pd(OAc)2 and 4,5-diazafluoren-9-one (DAF) as an ancillary ligand catalyze allylic oxidation with O2 in the absence of cocatalysts. Herein, we show that BQ enhances DAF/Pd(OAc)2 catalytic activity, nearly matching the performance of reactions that include both BQ and Co(salophen). These observations are complemented by mechanistic studies of DAF/Pd(OAc)2 catalyst systems under three different oxidation conditions: (1) O2 alone, (2) O2 with cocatalytic BQ, and (3) O2 with cocatalytic BQ and Co(salophen). The beneficial effect of BQ in the absence of Co(salophen) is traced to the synergistic roles of O2 and BQ, both of which are capable of oxidizing Pd0 to PdII. The reaction of O2 generates H2O2 as a byproduct, which can oxidize hydroquinone to quinone in the presence of PdII. NMR spectroscopic studies, however, show that hydroquinone is the predominant redox state of the quinone cocatalyst in the absence of Co(salophen), while inclusion of Co(salophen) maintains oxidized quinone throughout the reaction, resulting in better reaction performance.
- Kozack, Caitlin V.,Tereniak, Stephen J.,Jaworski, Jonathan N.,Li, Bao,Bruns, David L.,Knapp, Spring M. M.,Landis, Clark R.,Stahl, Shannon S.
-
-
Read Online
- Ag-Cu nanoparticles as efficient catalysts for transesterification of β-keto esters under acid/base-free conditions
-
Transesterification of β-keto esters and alcohols are traditionally catalyzed by acid or basic catalysts. However, these traditional catalysts do not always meet the requirements of modern synthetic chemistry which need to be highly efficient, selective, and environmentally friendly. In this work, Ag-Cu metal sites were first introduced as transesterification catalysts. The effect of the support, Ag:Cu molar ratio, and reaction conditions were investigated. The Ag-Cu metal sites were proved to be active in the β-ketoester transesterification with various alcohols, having yields comparable to the conventional acid- or base-catalysts.
- Yue, Hongmei,Yu, Hao,Liu, Sheng,Xu, Chunli
-
-
Read Online
- Development of a mild and efficient protocol for the protection and O-alkylation of allyl alcohols
-
An efficient, pyridine-free protocol has been developed for the protection of the 3°-allyl alcohol of oxindole using a mild base, such as potassium carbonate, under microwave irradiation conditions. The methodology has been tested with a variety of substrates and protecting group reagents, which provides a clean and good yield of the desired products within a short reaction time. the Partner Organisations 2014.
- Selvakumar, Kodirajan,Prasath Lingam, Kandapalam Arun,Luxmi Varma, Rama Varma
-
-
Read Online
- Silica chloride as a mild and efficient reagent for acetylation of alcohols
-
A variety of alcohols underwent acetylation with acetic anhydride in the presence of silica chloride. All reactions were performed at room temperature and under completely heterogeneous conditions in good to high yields.
- Shirini, Farhad,Zolfigol, Mohammad Ali,Khaleghi, Mahroo
-
-
Read Online
- Novel access to carbonyl and acetylated compounds: The role of the tetra-: N -butylammonium bromide/sodium nitrite catalyst
-
A novel aerobic oxidation of alcohols without the use of any oxidants was developed. An equimolar catalytic mixture of tetra-n-butylammonium bromide and sodium nitrite catalyzes the aerobic selective oxidation of benzylic alcohols under oxidant-free, base-free and metal-free conditions. The mild reaction conditions allow oxidation of a wide range of benzylic alcohols, chemo-selectively to their carbonyl compounds (68-93% isolated yields). More importantly, high selectivity among different kinds of alcohols (aromatic vs. aliphatic alcohols, primary vs. secondary alcohols as well as alcohols having neutral rings vs. electron-deficient rings) is available by this approach. The method surprisingly switched over to be an efficient acetylation approach in the case of aliphatic alcohols without the use of any transition metal, phosphorous or other toxic reagents or any need for using toxic acyl halides, sulfonyl halides, anhydrides, etc. by the use of only acetic acid as a reagent.
- Sheykhan, Mehdi,Moafi, Hadi Fallah,Abbasnia, Masoumeh
-
-
Read Online
- Bismuth (III) nitrate supported onto silica gel, a new catalyst for acetylation of alcohols and phenols under microwave irradiation
-
Bismuth (III) nitrate supported onto silica gel is found to be efficient catalyst for acetylation of alcohols, phenols and naphthals in the presence of acetic anhydride under microwave irradiation in solventless system.
- Asadolah, Karim,Heravi, Majid M.
-
-
Read Online
- PALLADIUM-CATALYZED ALLYLIC OXIDATION OF OLEFINS BY t-BUTYL HYDROPEROXIDE AND TELLURIUM(IV) OXIDE
-
Treatment of several cyclic olefins, β-pinene, allylbenzene and estragole with palladium(II) salt in acetic acid in the presence of t-butyl hydroperoxide and tellurium(IV) oxide afforded mainly the corresponding allylic acetates.The reaction proceeded catalytically with palladium(II) salt, t-BuOOH working as a reoxidazing agent.
- Uemura, Sakae,Fukuzawa, Shin-ichi,Toshimitsu, Akio,Okano, Masaya
-
-
Read Online
- [BF4]: Silver-free and acid-free catalysts for water-inclusive gold-mediated organic transformations
-
The synthesis of a series of digold hydroxide complexes is reported. These diaurated species, of the formula [{Au(NHC)}2(μ-OH)][BF 4] (where NHC = IPrCl, IPr, IPent), were easily prepared via the cationic species [Au(NHC)(NCCH3)][BF4] in aqueous media. The catalytic activity of these novel complexes was tested and compared to that of the previously reported IPr and SIPr derivatives. These digold hydroxide species are highly active in water-inclusive organic transformations, such as the alkyne and nitrile hydration reactions, and the Meyer-Schuster rearrangement. One salient feature of these systems is the lack of any additive to induce catalytic activity.
- Gomez-Suarez, Adrian,Oonishi, Yoshihiro,Meiries, Sebastien,Nolan, Steven P.
-
-
Read Online
- SECONDARY TRITIUM ISOTOPE EFFECTS, A USEFUL MECHANISTIC PROBE FOR THE STUDY OF ACETOXYL PARTICIPATION AND TRANSFER
-
Tritium labelling on the acetoxyl methyl group has been used to probe the mode of incorporation of acetate into cinnamyl acetate in the solvolyses of cinnamyl chloride and cinnamylmercuric acetate, and in the allylic oxidation of allylbenzene with mercuric acetate.
- Wolfe, Saul,Campbell, Peter G. C.
-
-
Read Online
- Manganese-mediated acetylation of alcohols, phenols, thiols, and amines utilizing acetic anhydride
-
Manganese(II) chloride-catalyzed acetylation of alcohols, phenols thiols and amines with acetic anhydride is reported. This method is environment-friendly and economically viable as it involves inexpensive, relatively benign catalyst, mild reaction condition, and simple workup. Acetylation is performed under the solvent-free condition at ambient temperature and acetylated products obtained in good to excellent yields. Primary, secondary heterocyclic amines, and phenols with various functional groups are smoothly acetylated in good yields. This method exhibits exquisite chemoselectivity, the amino group is preferentially acetylated in the presence of a hydroxyl/thiol group.
- Jain, Isha,Sharma, Ramandeep,Malik, Payal
-
-
Read Online
- Lipase catalyzed synthesis of cinnamyl acetate via transesterification in non-aqueous medium
-
Cinnamyl acetate is used as flavor and fragrance ingredient in food and cosmetic industries. This work focuses on the synthesis of cinnamyl acetate via lipase catalyzed transesterification of cinnamyl alcohol with vinyl acetate in non-aqueous medium. Among the different immobilized lipases employed, Novozym 435 was found to be the best catalyst in toluene as solvent. The effects of various parameters were studied systematically. With a mole ratio of 1:2 of cinnamyl alcohol to vinyl acetate and 10 mg catalyst, 96% conversion was obtained in 1 h at 40 °C. The ternary complex mechanism with inhibition by cinnamyl alcohol was found to fit the data well. The kinetics of the reaction was studied by using non-linear regression analysis. Enzymatic synthesis of cinnamyl acetate is an efficient process vis-a?-vis chemical catalysis.
- Yadav, Ganapati D.,Devendran, Saravanan
-
-
Read Online
- Diastereoselective carbonyl allylation with simple olefins enabled by palladium complex-catalyzed C-H oxidative borylation
-
A highly diastereoselective Pd-catalyzed carbonyl allylation of aldehydes and isatins directly using simple acyclic olefins as allylating reagents is described. This transformation is actually a sequential process consisting of a Pd-catalyzed oxidative allylic C-H borylation and an allylboration of carbonyls accelerated by phosphoric acid, wherein a wide scope of olefins could be tolerated. The oxidant is revealed to play a key role in the successful realization of the allylic C-H activation-based allylation.
- Tao, Zhong-Lin,Li, Xing-Han,Han, Zhi-Yong,Gong, Liu-Zhu
-
-
Read Online
- Pd-Catalyzed Cascade Reactions of Aziridines: One-Step Access to Complex Tetracyclic Amines
-
The combination of palladium catalysis and thermal cycloaddition is shown to transform tricyclic aziridines into complex, stereodefined tetracyclic products in a single step. This highly unusual cascade process involves a diverted Tsuji-Trost sequence leading to a surprisingly facile intramolecular Diels-Alder reaction. The starting materials are accessible on multigram scales from the photochemical rearrangement of simple pyrroles. The tetracyclic amine products can be further elaborated through routine transformations, highlighting their potential as scaffolds for medicinal chemistry.
- Booker-Milburn, Kevin I.,Knowles, Jonathan P.,Latter, Francesca,Schwarz, Maria,Steeds, Hannah G.
-
-
Read Online
- A Sulfoxide-Promoted, Catalytic Method for the Regioselective Synthesis of Allylic Acetates from Monosubstituted Olefins via C-H Oxidation
-
Sulfoxide ligation to Pd(II) salts is shown to selectively promote C-H oxidation versus Wacker oxidation chemistry and to control the regioselectivity in the C-H oxidation products. A catalytic method for the direct C-H oxidation of monosubstituted olefins to linear (E)-allylic acetates in high regio- and stereoselectivities and preparatively useful yields is described. The method using benzoquinone as the stoichiometric oxidant and 10 mol % of Pd(OAc)2 or Pd(O2CCF3)2 as the catalyst in a DMSO/AcOH (1:1) solution was found to be compatible with a wide range of functionality (e.g., amides, carbamates, esters, and ethers, see Table 2). Addition of DMSO was found to be critical for promoting the C-H oxidation pathway, with AcOH alone or in combination with a diverse range of dielectric media, leading to mixtures favoring Wacker-type oxidation products (Tables 1, S3). To explore the role of DMSO as a ligand, the bis-sulfoxide Pd(OAc)2 complex 1 was formed and found to be an effective C-H oxidation catalyst in the absence of DMSO (eqs 2, 3). Moreover, catalyst 1 effects a reversal of regioselectivity, favoring the formation of branched allylic acetates. Copyright
- Chen, Mark S.,White, M. Christina
-
-
Read Online
- Regioselective Acetoxylation of Terminal Olefins Using a Palladium(II)–Thiadiazole Catalyst
-
First-time use of a palladium(II)–thiadiazole catalyst in the allylic oxidation of terminal olefins to linear allylic acetates. Employing this strategy, a range of allylic esters (20 examples) were synthesized in 43 % to 80 % yield with excellent regio- and stereoselectivities.
- Li, Xiaohan,Sun, Bin,Zhou, Jiadi,Jin, Can,Yu, Chuangming
-
-
Read Online
- Magnetically separable γ-Fe2O3 nanoparticles: An efficient catalyst for acylation of alcohols, phenols, and amines using sonication energy under solvent free condition
-
This paper reports a facile synthesis of magnetically separable iron oxide (γ-Fe2O3) nanoparticles using thermolysis method. The structural and morphological study of the synthesized γ-Fe2O3 nanoparticles was carried out using X-ray diffraction (XRD), field emission gun-scanning electron microscopy (FEG-SEM), energy dispersive X-ray spectrum (EDS), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), and X-ray photoelectron spectroscopy (XPS) techniques. The electron microscopy reveals that the γ-Fe2O3 nanoparticles have spherical morphology with a particle size in the range of 40-100 nm. The XPS study confirmed the Fe is in +3 oxidation state. The synthesized γ-Fe2O3 nanoparticles have been used as an efficient heterogeneous catalyst for the organic transformation between phenols, alcohols, and amines with acetic anhydride under sonication using mild reaction conditions. Various electrons withdrawing and electrons donating substrates show an excellent yield of desired products with the advantage of magnetic separation and reusability of γ-Fe2O3 nanocatalyst.
- Bhosale, Manohar A.,Ummineni, Divya,Sasaki, Takehiko,Nishio-Hamane, Daisuke,Bhanage, Bhalchandra M.
-
-
Read Online
- Pd(0)-catalyzed 1,1-diarylation of ethylene and allylic carbonates
-
An efficient protocol for the one-step synthesis of biologically relevant 1,1-diarylalkanes has been described. This reaction introduces two different aryl groups across the terminal end of simple feedstock alkenes such as ethylene and allylic carbonates.
- Saini, Vaneet,Liao, Longyan,Wang, Qiaofeng,Jana, Ranjan,Sigman, Matthew S.
-
-
Read Online
- Lipase immobilized on novel ceramic supporter with Ni activation for efficient cinnamyl acetate synthesis
-
The metal ceramic powder (MCP) was used for lipase immobilization. The MCP containing Ni2+(Ni-MCP)exhibited the best affinity to lipase. The effects of heating rate, lipase concentration and immobilizationtime on immobilized lipase (Ni-MCP-lipase) activity were measured. Under the optimal preparationconditions (heating rate: 1°C/min, lipase concentration: 9 mg/mL, immobilization time: 8 h), Ni-MCP-lipase could obtain 1.4 U/g and 216% of activity yield. The Ni-MCP-lipase, with improved thermal stabilityand storage stability, had optimal pH value of 6.0 and optimal temperature of 40°C. The characterizationsclarified the effect of heating rate on Ni-MCP-lipase activity, and confirmed that lipase had been efficientlyimmobilized on Ni-MCP surface. Finally, cinnamyl acetate synthesis demonstrated that Ni-MCP-lipasehad improved efficiency compared with free lipase. Under the optimal reaction conditions (Ni-MCP-lipaseloading: 3 g; reaction temperature: 35°C; acetic acid/cinnamyl alcohol: 2:1 in 15.0 mL reaction system),the cinnamyl acetate yield would reach 62.56%.
- Wu, Zhongjie,Qi, Wei,Wang, Mengfan,Su, Rongxin,He, Zhimin
-
-
Read Online
- Facile One-Pot Immobilization of a Novel Esterase and Its Application in Cinnamyl Acetate Synthesis
-
Abstract: Cinnamyl acetate has a wide application in food industries. This work focuses on cinnamyl acetate synthesis with a novel esterase. estGUZ753, an esterase gene from Geobacillus uzenensis DSMZ 13551, was first cloned and expressed in Pichia pastoris KM71. The optimal activity of EstGUZ753 towards p-NP caprylate was at pH 8.0 and 70?°C, and the half-life at 70?°C was 28?h. Furthermore, EstGUZ753 showed marked tolerance in methanol. The activity of EstGUZ753 increased up to 1.16-fold in 90% methanol after 72?h, and the half-life in it was 336?h. The crude fermentation broth of EstGUZ753 was immobilized directly onto the epoxy resin (Lx-105s), and the immobilized EstGUZ753 exhibited a 99% conversion for cinnamyl acetate synthesis at a high cinnamyl alcohol concentration in 6?h (cinnamyl alcohol: 1.0?M, enzyme dosage: 3%). These characteristics of EstGUZ753 indicated its great potential for organic synthesis. Graphic Abstract: A novel esterase gene from Geobacillus uzenensis DSMZ 13551 was first cloned and expressed in Pichia pastoris KM71. Esterase EstGUZ753 showed marked thermostability at high temperature and tolerance in methanol. Furthermore, the crude fermentation broth of EstGUZ753 was immobilized directly onto the epoxy resin, and immobilized EstGUZ753 exhibited a 99% conversion for cinnamyl acetate synthesis.[Figure not available: see fulltext.]
- Dong, Fengying,Lin, Lin,Wei, Wei,Wei, Dongzhi
-
-
Read Online
- Synthesis of dinuclear (μ-η3-Allyl)palladium(I) and -platinum(I) complexes supported by chelate-bridging ligands
-
Dinuclear (μ-η3-allyl)palladium(I) complexes supported by chelate-bridging ligands, (μ-η3-allyl)Pd2(μ-L) (L = N,N′-bis[2-(diphenylphosphino)phenyl]formamidinate, N-(2-diphenylphosphino)phenyl-N′-8-quinolylformamidinate, N,N′-di-8-quinolylformamidinate, N,N′-di-8-quinolylacetamidinate), were synthesized, and some of them were characterized by X-ray crystallography. A dinuclear (μ-η3-allyl)platinum(I) complex, (μ-η3-allyl)Pt2(μ-L), was also synthesized and crystallographically characterized.
- Yamaguchi, Yu,Yamanishi, Katsunori,Kondo, Mitsuru,Tsukada, Naofumi
-
-
Read Online
- HY Zeolite as an extremely active and reusable catalyst in acylation of alcohols with acid anhydride in a solventless system
-
HY Zeolite is a practical and useful catalyst for acylation of various alcohols and phenols.
- Heravi,Bolourtchian,Nakhshab,Zadmard
-
-
Read Online
- Terephthalic acid derived ligand-stabilized palladium nanocomposite catalyst for Heck coupling reaction: without surface-modified heterogeneous catalyst
-
A new protocol is reported for the synthesis of a heterogeneous palladium nanocomposite stabilized with a terephthalic acid-derived ligand (N,N-bis(4-hydroxy-3-methoxybenzylidene)terephthalohydrazide). This is a highly insoluble ligand in common organic solvents, except dimethylformamide and dimethylsulfoxide. The resulting palladium nanocomposite acts as an efficient catalyst precursor for Mizoroki–Heck coupling reactions conducted under various reaction conditions. The spectral data suggest that the rate, yield and recycling of the catalyst are more effective for C–C coupling reactions. Copyright
- Jithendra kumara,Krishnamurthy,Kumara swamy,Shashi kumar,Naik, Satish,Krishna,Naik, Nagaraj
-
-
Read Online
- Magnetically recyclable silica-coated ferrite magnetite-K10montmorillonite nanocatalyst and its applications in O, N, and S-acylation reaction under solvent-free conditions
-
Novel silica-coated ferrite nanoparticles supported with montmorillonite (K10) have been prepared successfully by using a simple impregnation method. Further, these nanoparticles were characterized by using different analytical methods like FT-IR, PXRD, EDS, and FE-SEM techniques. In addition, these nanoparticles have been explored for their catalytic activity for the O, N, and S-acylation reactions under solvent-free conditions which gave moderate to excellent yields in a much shorter reaction time. Moreover, these nanoparticles could easily be separated out from the reaction medium after the reaction completion by using an external magnetic field and have been re-used for 10 cycles without any significant loss of the catalytic activity.
- Kumar, Pushpendra,Patil, Shripad M.,Tandon, Nitin,Tandon, Runjhun
-
-
Read Online
- KF-Al2O3 is an efficient solid support reagent for the acetylation of amines, alcohols, and phenols. Impeding effect of solvent on the reaction rate
-
KF-Al2O3 brings about rapid acetylation of a range of amines, alcohols, and phenols with Ac2O/AcCl. Aliphatic alcohols are acetylated chemoselectively in the presence of phenols. 1° alcohols react several times faster than 2° alcohols. 3° alcohols do not react.
- Yadav, Veejendra K,Ganesh Babu,Mittal, Manish
-
-
Read Online
- Chemoselective acetylation of alcohols, amines, and thiols without catalyst and solvent
-
Microwave induced rapid and selective acetylation of alcohols, amines and thiols with acetic anhydride was carried out under non-catalytic and solvent free conditions.
- Bandgar,Kasture,Kamble
-
-
Read Online
- Detection of Palladium(I) in Aerobic Oxidation Catalysis
-
Palladium(II)-catalyzed oxidation reactions exhibit broad utility in organic synthesis; however, they often feature high catalyst loading and low turnover numbers relative to non-oxidative cross-coupling reactions. Insights into the fate of the Pd catalyst during turnover could help to address this limitation. Herein, we report the identification and characterization of a dimeric PdI species in two prototypical Pd-catalyzed aerobic oxidation reactions: allylic C?H acetoxylation of terminal alkenes and intramolecular aza-Wacker cyclization. Both reactions employ 4,5-diazafluoren-9-one (DAF) as an ancillary ligand. The dimeric PdI complex, [PdI(μ-DAF)(OAc)]2, which features two bridging DAF ligands and two terminal acetate ligands, has been characterized by several spectroscopic methods, as well as single-crystal X-ray crystallography. The origin of this PdI complex and its implications for catalytic reactivity are discussed.
- Jaworski, Jonathan N.,McCann, Scott D.,Guzei, Ilia A.,Stahl, Shannon S.
-
-
Read Online
- A sustainable one-pot synthesis of cinnamyl acetate in triacetin
-
A sustainable one-pot synthesis of cinnamyl acetate from cinnamaldehyde is demonstrated for the first time using immobilized Baker's yeast and free or immobilized acid as catalysts and triacetin as solvent. Employing the immobilized yeast and Amberlyst-36 allowed full conversion and 91% selectivity for cinnamyl acetate after 96 h at room temperature, and both the catalysts and triacetin were successfully recycled.
- Wolfson, Adi,Dlugy, Christina,Karanet, Anna,Tavor, Dorith
-
-
Read Online
- Flow chemistry as a discovery tool to access sp2-sp3 cross-coupling reactions via diazo compounds
-
The work takes advantage of an important feature of flow chemistry, whereby the generation of a transient species (or reactive intermediate) can be followed by a transfer step into another chemical environment, before the intermediate is reacted with a coupling partner. This concept is successfully applied to achieve a room temperature sp2-sp3 cross coupling of boronic acids with diazo compounds, these latter species being generated from hydrazones under flow conditions using MnO2 as the oxidant.
- Tran, Duc N.,Battilocchio, Claudio,Lou, Shing-Bong,Hawkins, Joel M.,Ley, Steven V.
-
-
Read Online
- Biogenic CuFe2O4 magnetic nanoparticles as a green, reusable and excellent nanocatalyst for acetylation reactions under solvent-free conditions
-
A convenient green method has been developed for the synthesis of biogenic CuFe2O4 magnetic nanoparticles using tea extracts within a very short reaction time. The prepared nanoparticles with an average size of 8.78 nm have been used as an effective catalyst for the acetylation of various alcohols, phenols and amines in good to excellent yields under solvent-free conditions. The catalyst was characterized by XRD, XPS, VSM, SEM and TEM study. A magnetic study of the fresh and recycled catalyst after the fourth cycle was performed by VSM measurement. The main advantages of this protocol are simple biogenic synthesis of the catalyst, a reusable and heterogeneous catalytic system, and short reaction times with excellent yields.
- Chutia, Rituparna,Chetia, Bolin
-
-
Read Online
- A pronounce approach on the catalytic performance of mesoporous natural silica toward esterification of acetic acid with iso-amyl, benzyl, and cinnamyl alcohols
-
Catalytic esterification of acetic acid with iso-amyl, benzyl, and cinnamyl alcohols in the liquid phase over unmodified natural silica catalyst has been studied. The virgin and calcined catalysts were characterized by thermal analyses (Thermogravimetry (TG) and diffrential thermal analysis (DTA)), X-ray diffraction (XRD), X-ray fluorescence (XRF), Fourier transform infrared (FTIR), scanning electron microscope (SEM), and N2 sorption analyses. The acidity of natural silica catalysts was investigated using isopropyl alcohol dehydration and chemisorption of pyridine and dimethyl pyridine. The results indicated that most of the acidic sites are of Br?nsted type and of intermediate strength. The effect of different parameters such as reaction time, molar ratio, catalyst dosage, and calcination temperature was studied. Natural silica catalyst exhibited excellent catalytic performance with a selectivity of 100% to acetate esters formation. The maximum yields of isoamyl, benzyl, and cinnamyl acetate esters obtained in the batch conditions were 80, 81, and 83%, respectively. Whereas on adopting a simple distillation technique, these yields were successfully improved to higher values of 97, 98, and 90%, respectively. Experimental results manifested that the reaction followed Langmuir–Hinshelwood mechanism. Finally, the catalyst could be completely recycled without loss of its activity after four cycles of the esterification reactions.
- Abd El-Wahab, Mohamed M. M.,El-Gamal, Nadia O.,Goda, Mohamed N.,Said, Abd El-Aziz A.
-
-
- Ring-Closing Metathesis of Aliphatic Ethers and Esterification of Terpene Alcohols Catalyzed by Functionalized Biochar
-
Functionalized biochars, renewable carbon materials prepared from waste biomass, can catalyze transformations of a range of oxygen-containing substrates via hydrogen-bonding interactions. Good conversions (up to 75.2 %) to different O-heterocycles are obtained from ring-closing C?O/C?O metathesis reactions of different aliphatic ethers under optimized conditions using this heterogeneous, metal-free, and easy separable catalyst. The diversity in the sorts of O-containing feedstocks is further demonstrated by the utilization of functionalized biochar to promote the esterification of terpene alcohols, an important reaction in food and flavor industries. Under the optimized conditions, full conversions to various terpene esters are obtained. Moreover, both of the reactions studied herein are performed under neat conditions, thus increasing the overall sustainability of the process described.
- Kerton, Francesca M.,MacQuarrie, Stephanie L.,Vidal, Juliana L.,Wyper, Olivia M.
-
supporting information
p. 6052 - 6056
(2021/12/10)
-
- Evaluation of gem-Diacetates as Alternative Reagents for Enzymatic Regio-and Stereoselective Acylation of Alcohols
-
Geminal diacetates have been used as sustainable acyl donors for enzymatic acylation of chiral and nonchiral alcohols. Especially, it was revealed that geminal diacetates showed higher reactivity than vinyl acetate for hydrolases that are sensitive to acetaldehyde. Under optimized conditions for enzymatic acylation, several synthetically relevant saturated and unsaturated acetates of various primary alcohols were obtained in very high yields up to 98% without E/Z isomerization of the double bond. Subsequently, the acyl donor was recreated from the resulting aldehyde and reused constantly in acylation. Therefore, the developed process is characterized by high atomic efficiency. Moreover, it was shown that acylation using geminal diacetates resulted in remarkable regioselectivity by discriminating among the primary and secondary hydroxyl groups in 1-phenyl-1,3-propanediol providing exclusively 3-acetoxy-1-phenyl-propan-1-ol in good yield. Further, enzymatic kinetic resolution (EKR) and chemoenzymatic dynamic kinetic resolution (DKR) protocols were developed using geminal diacetate as an acylating agent, resulting in chiral acetates in high yields up to 94% with enantiomeric excesses exceeding 99%.
- Koszelewski, Dominik,Brodzka, Anna,Madej, Arleta,Trzepizur, Damian,Ostaszewski, Ryszard
-
p. 6331 - 6342
(2021/05/06)
-
- 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 0012; 0013; 0028
(2021/01/29)
-
- KMnO4-catalyzed chemoselective deprotection of acetate and controllable deacetylation-oxidation in one pot
-
A novel and efficient protocol for chemoselective deacetylation under ambient conditions was developed using catalytic KMnO4. The stoichiometric use of KMnO4 highlighted the dual role of a heterogeneous oxidant enabling direct access to aromatic aldehydes in one-pot sequential deacetylation-oxidation. The reaction employed an alternative solvent system and allowed the clean transformation of benzyl acetate to sensitive aldehyde in a single step while preventing over-oxidation to acids. Use of inexpensive and readily accessible KMnO4 as an environmentally benign reagent and the ease of the reaction operation were particularly attractive, and enabled the controlled oxidation and facile cleavage of acetate in a preceding step. This journal is
- Gurawa, Aakanksha,Kumar, Manoj,Rao, Dodla S.,Kashyap, Sudhir
-
supporting information
p. 16702 - 16707
(2020/10/27)
-
- Regioselective Wacker-Type Oxidation of Internal Olefins in tBuOH Using Oxygen as the Sole Oxidant and tBuONO as the Organic Redox Cocatalyst
-
A regioselective Wacker-Tsuji oxidation of internal olefins in tBuOH has been developed using oxygen as the terminal oxidant and tert-butyl nitrite as the simple organic redox cocatalyst without the involvement of hazardous cocatalysts or harsh reaction conditions. A series of internal olefins bearing various functional groups can be oxidized to the corresponding substituted ketones in generally good yields with high regioselectivities.
- Huang, Qing,Li, Ya-Wei,Ning, Xiao-Shan,Jiang, Guo-Qing,Zhang, Xiao-Wei,Qu, Jian-Ping,Kang, Yan-Biao
-
supporting information
p. 965 - 969
(2020/02/15)
-
- Scalable green approach toward fragrant acetates
-
The advantageous properties of ethylene glycol diacetate (EGDA) qualify it as a useful substitute for glycerol triacetate (GTA) for various green applications. We scrutinised the lipase-mediated acetylation of structurally diverse alcohols in neat EGDA furnishing the range of naturally occurring fragrant acetates. We found that such enzymatic system exhibits high reactivity and selectivity towards activated (homo) allylic and non-activated primary/secondary alcohols. This feature was utilised in the scalable multigram synthesis of fragrant (Z)-hex-3-en-1-yl acetate in 70percent yield. In addition, the Lipozyme 435/EGDA system was also found to be applicable for the chemo-selective acetylation of (hydroxyalkyl) phenols as well as for the kinetic resolution of chiral secondary alcohols. Lastly, its discrimination power was demonstrated in competitive experiments of equimolar mixtures of two isomeric alcohols. This enabled the practical synthesis of 1-pentyl acetate isolated as a single product in 68percent yield from the equimolar mixture of 1-pentanol and 3-pentanol.
- Puchl'Ová, Eva,Szolcsányi, Peter
-
-
- Styrene Production from Benzene and Ethylene Catalyzed by Palladium(II): Enhancement of Selectivity toward Styrene via Temperature-dependent Vinyl Ester Consumption
-
Oxidative ethylene hydrophenylation catalyzed by palladium(II) acetate with Cu(II) oxidants to produce styrene generally suffers from low selectivity and/or low yield. Commonly observed side products include vinyl carboxylates and stilbene. In this Article, the selectivity for styrene formation by Pd(OAc)2 is studied as a function of reaction temperature, ethylene pressure, Br?nsted acid additive, Cu(II) oxidant amount, and oxygen pressure. Under optimized conditions, at high temperatures (180 °C) and low olefin pressure (20 psig), nearly quantitative yield (>95%) of styrene is produced based on the limiting reagent copper(II) pivalate. We propose the selectivity for styrene versus vinyl pivalate at 180 °C is due to a palladium-catalyzed conversion of benzene and in situ formed vinyl pivalate to styrene.
- Jia, Xiaofan,Foley, Aisling M.,Liu, Chang,Vaughan, Benjamin A.,McKeown, Bradley A.,Zhang, Sen,Gunnoe, T. Brent
-
supporting information
p. 3532 - 3541
(2019/09/12)
-
- 'Clean' hydrolase reactions using commercial washing powder
-
We report the use of commercial laundry powder as a biocatalyst for a range of lipase-catalysed reactions including (trans)esterification, ester hydrolysis and chemoenzymatic epoxidation reactions. The enzymatic laundry powder exhibited excellent stability and recyclability, making it a readily available and cheap biocatalyst for chemical transformations.
- Zhang, Jie,Tonin, Fabio,Zhang, Wuyuan,Hagedoorn, Peter-Leon,Mallée, Lloyd,Hollmann, Frank
-
p. 24039 - 24042
(2019/08/15)
-
- Amide/Iminium Zwitterionic Catalysts for (Trans)esterification: Application in Biodiesel Synthesis
-
A class of zwitterionic organocatalysts based on an amide anion/iminium cation charge pair has been developed. The zwitterions are easily prepared by reacting aziridines with aminopyridines. They are catalytically applicable to transesterifications and dehydrative esterifications. Mechanistic studies reveal that the amide anion and iminium cation work synergistically in activating the reaction partners, with the iminium cationic moiety interacting with the carbonyl substrates through nonclassical hydrogen bonding. The reaction can be applied to large-scale synthesis of biodiesel under mild conditions.
- Lam, Ying-Pong,Ng, Wing-Hin,Tan, Fei,Tse, Ying-Lung Steve,Wang, Xinyan,Yeung, Ying-Yeung
-
p. 8083 - 8092
(2019/08/26)
-
- Efficient Enzymatic Preparation of Flavor Esters in Water
-
A straightforward biocatalytic method for the enzymatic preparation of different flavor esters starting from primary alcohols (e.g., isoamyl, n-hexyl, geranyl, cinnamyl, 2-phenethyl, and benzyl alcohols) and naturally available ethyl esters (e.g., formate, acetate, propionate, and butyrate) was developed. The biotransformations are catalyzed by an acyltransferase from Mycobacterium smegmatis (MsAcT) and proceeded with excellent yields (80-97%) and short reaction times (30-120 min), even when high substrate concentrations (up to 0.5 M) were used. This enzymatic strategy represents an efficient alternative to the application of lipases in organic solvents and a significant improvement compared with already known methods in terms of reduced use of organic solvents, paving the way to sustainable and efficient preparation of natural flavoring agents.
- Perdomo, Igor Chiarelli,Gianolio, Stefania,Pinto, Andrea,Romano, Diego,Contente, Martina Letizia,Paradisi, Francesca,Molinari, Francesco
-
p. 6517 - 6522
(2019/06/20)
-
- Fe3O4@PEG core/shell nanoparticles as magnetic nanocatalyst for acetylation of amines and alcohols using ultrasound irradiations under solvent-free conditions
-
Abstract: Ultrasound irradiation was used to prepare one-pot Fe3O4@PEG core/shell nanostructure for the first time. The morphology, structure, and physicochemical properties were specified by different analytical techniques including field emission scanning electron microscopy, Fourier transform infrared spectroscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy, X-ray powder diffraction, and vibrating sample magnetometer. For acetylation of phenols, alcohols, and amines, the synthesized Fe3O4@PEG core/shell nanoparticles were used as an efficient heterogeneous and green catalyst with acetic anhydride under sonication applying mild reaction conditions. Different electron-withdrawing and electron-donating substrates indicate a prominent yield of desired products with the merit of reusability of Fe3O4@PEG nanocatalyst and magnetic separation. Graphical Abstract: [Figure not available: see fulltext.].
- Veisi, Hojat,Nikseresht, Ahmad,Rostami, Afsaneh,Hemmati, Saba
-
p. 507 - 520
(2018/10/24)
-
- Coating of polydopamine on polyurethane open cell foams to design soft structured supports for molecular catalysts
-
Polydopamine-coated polyurethane open cell foams are used as structured supports for molecular catalysts through the covalent anchoring of alkoxysilyl arms by the catechol groups of the mussel-inspired layer. This strong bonding prevents their leaching. No alteration of the mechanical properties of the flexible support is observed after repeated uses of the catalytic materials.
- Ait Khouya, Ahmed,Mendez Martinez, Miguel L.,Bertani, Philippe,Romero, Thierry,Favier, Damien,Roland, Thierry,Guidal, Valentin,Bellière-Baca, Virginie,Edouard, David,Jierry, Lo?c,Ritleng, Vincent
-
supporting information
p. 11960 - 11963
(2019/10/11)
-
- Operando Spectroscopic and Kinetic Characterization of Aerobic Allylic C-H Acetoxylation Catalyzed by Pd(OAc)2/4,5-Diazafluoren-9-one
-
Allylic C-H acetoxylations are among the most widely studied palladium(II)-catalyzed C-H oxidation reactions. While the principal reaction steps are well established, key features of the catalytic mechanisms are poorly characterized, including the identity of the turnover-limiting step and the catalyst resting state. Here, we report a mechanistic study of aerobic allylic acetoxylation of allylbenzene with a catalyst system composed of Pd(OAc)2 and 4,5-diazafluoren-9-one (DAF). The DAF ligand is unique in its ability to support aerobic catalytic turnover, even in the absence of benzoquinone or other co-catalysts. Herein, we describe operando spectroscopic analysis of the catalytic reaction using X-ray absorption and NMR spectroscopic methods that allow direct observation of the formation and decay of a palladium(I) species during the reaction. Kinetic studies reveal the presence of two distinct kinetic phases: (1) a burst phase, involving rapid formation of the allylic acetoxylation product and formation of the dimeric PdI complex [PdI(DAF)(OAc)]2, followed by (2) a post-burst phase that coincides with evolution of the catalyst resting state from the PdI dimer into a π-allyl-PdII species. The data provide unprecedented insights into the role of ancillary ligands in supporting catalytic turnover with O2 as the stoichiometric oxidant and establish an important foundation for the development of improved catalysts for allylic oxidation reactions.
- Jaworski, Jonathan N.,Kozack, Caitlin V.,Tereniak, Stephen J.,Knapp, Spring Melody M.,Landis, Clark R.,Miller, Jeffrey T.,Stahl, Shannon S.
-
supporting information
p. 10462 - 10474
(2019/07/09)
-
- Palladium-catalyzed allylic C-H oxidation under simple operation and mild conditions
-
We discovered an effective and simple system (Pd/BQ/air/r.t.) for making allylic alcohols through Pd-catalyzed allylic C-H bond functionalization. This approach exhibits advantages due to its simple operation, mild conditions, and environmentally benign features. By modifying reaction conditions, it can be suitable for preparing unsaturated aldehydes, allylic esters, ethers, and amines.
- Guo, Yunlong,Shen, Zengming
-
supporting information
p. 3103 - 3107
(2019/03/26)
-
- Protection of COOH and OH groups in acid, base and salt free reactions
-
We report an iron-catalyzed general functional group protection method with inexpensive reagents. This environmentally benign process does not use acids or bases, and does not produce waste products. Further purification beyond filtration and evaporation is, in most cases, unnecessary. Free COOH and OH groups can be protected in a one-pot reaction.
- Zhu, Xiaotao,Qian, Bo,Wei, Rongbiao,Huang, Jian-Dong,Bao, Hongli
-
supporting information
p. 1444 - 1447
(2018/04/12)
-
- Preparation of Polydopamine Sulfamic Acid-Functionalized Silica Gel as Heterogeneous and Recyclable Nanocatalyst for Acetylation of Alcohols and Amines Under Solvent-Free Conditions
-
To fabricate SiO2/PDA–SO3H nanocatalyst, a suitable method is designed for the loading of sulfonic acid groups on the surface of polydopamine (PDA)-encapsulated SiO2 nanoparticles. To bridge the gap between heterogeneous and homogeneous catalysis, surface functionalization of silica gel is an elegant procedure. The morphology, structure, and physicochemical features were specified using different analytical techniques including field emission scanning electron microscopy (FESEM), Fourier transformed infrared spectroscopy (FT-IR), high resolution-transmission electron microscopy (HR-TEM), energy dispersive X-ray spectroscopy (EDS), wavelength-dispersive X-ray spectroscopy (WDX), X-ray photoelectron spectroscopy (XPS), and back titration. The SiO2/PDA–SO3H nanoparticles are efficient nanocatalysts for the acetylation of many alcohols, phenols, and amines with acetic anhydride under solvent-free conditions in good to excellent yields. Moreover, the reuse and recovery of the catalyst was shown seven times without detectible loss in activity. Graphical Abstract: [Figure not available: see fulltext.]
- Veisi, Hojat,Vafajoo, Saba,Bahrami, Kiumars,Mozafari, Bita
-
p. 2734 - 2745
(2018/07/30)
-
- Dehydroxylation of alcohols for nucleophilic substitution
-
The Ph3P/ICH2CH2I system-promoted dehydroxylative substitution of alcohols was achieved to construct C-O, C-N, C-S and C-X (X = Cl, Br, and I) bonds. Compared with the previous approaches such as the Appel reaction and Mitsunobu reaction, this protocol offers some practical advantages such as safe operation and a convenient amination process.
- Chen, Jia,Lin, Jin-Hong,Xiao, Ji-Chang
-
p. 7034 - 7037
(2018/07/05)
-
- Electrochemical properties and reactions of organoboronic acid esters containing unsaturated bonds at their α-position
-
Electrochemical analyses of 2-(cynnamyl)boronic acid pinacol ester and (3-phenyl-2-propynyl)boronic acid pinacol ester, and their trimethylsilyl analogues as well as their parent compounds were comparatively studied by cyclic voltammetry measurements. We
- Ohtsuka, Kazuhiro,Inagi, Shinsuke,Fuchigami, Toshio
-
p. G23 - G28
(2017/12/26)
-
- Additive-free pd-catalyzed α-allylation of imine-containing heterocycles
-
An additive-free Pd-catalyzed α-allylation of different imino-group-ontaining heterocycles is reported. The activation of α-CH pronucleophiles (pKa (DMSO) > 25) occurs without the addition of strong bases or Lewis acids using only the Pd/Xantphos catalyst system. The reaction scope has been studied for various 5- and 6-membered nitrogen-containing heterocycles (yields up to 96%). Mechanistic investigations suggest an initial allylation of the imine-N followed by a Pd-catalyzed formal aza-Claisen rearrangement.
- Kljajic, Marko,Puschnig, Johannes G.,Weber, Hansj?rg,Breinbauer, Rolf
-
supporting information
p. 126 - 129
(2017/11/27)
-
- Reusable and efficient polyvinylpolypyrrolidone-supported triflic acid catalyst for acylation of alcohols, phenols, amines, and thiols under solvent-free conditions
-
Abstract: A triflic acid-functionalized polyvinylpolypyrrolidone was prepared and fully characterized by FT-IR, TGA, and SEM. This super acidic solid catalyst shows high catalytic activity for selective acylation of alcohols, phenols, amines, and thiols with anhydrides under solvent-free conditions at room temperature. In addition, this method features an easy to handle solid super acid catalyst and an operationally simple procedure, affording the desired acylated products in excellent yields. Graphical abstract: [Figure not available: see fulltext.].
- Tajbakhsh, Mahgol,Tajbakhsh, Mahmoud,Khaksar, Samad,Gazvini, Helia Janatian,Heidary, Marzieh
-
p. 1117 - 1122
(2017/05/10)
-
- Oxygenation of Simple Olefins through Selective Allylic C?C Bond Cleavage: A Direct Approach to Cinnamyl Aldehydes
-
A novel metal-free allylic C?C σ-bond cleavage of simple olefins to give valuable cinnamyl aldehydes is reported. 1,2-Aryl or alkyl migration through allylic C?C bond cleavage occurs in this transformation, which is assisted by an alkyl azide reagent. This method enables O-atom incorporation into simple unfunctionalized olefins to construct cinnamyl aldehydes. The reaction features simple hydrocarbon substrates, metal-free conditions, and high regio- and stereoselectivity.
- Liu, Jianzhong,Wen, Xiaojin,Qin, Chong,Li, Xinyao,Luo, Xiao,Sun, Ao,Zhu, Bencong,Song, Song,Jiao, Ning
-
supporting information
p. 11940 - 11944
(2017/09/20)
-
- Transesterification Reactions Catalyzed by a Recyclable Heterogeneous Zinc/Imidazole Catalyst
-
We report the development of a universal and recyclable heterogeneous zinc/imidazole catalyst. The catalyst is recoverable through simple filtration and can be reused at least five times, retaining its catalytic activity. Leached zinc species were not responsible for the observed catalysis based on the hot filtration test and ICP-MS analysis. The heterogeneous zinc catalyst also promotes chemoselective transesterification over amidation. (Figure presented.).
- Nakatake, Daiki,Yazaki, Ryo,Matsushima, Yoshimasa,Ohshima, Takashi
-
supporting information
p. 2569 - 2574
(2016/08/16)
-
- Selective acetylation of primary alcohols by ethyl acetate
-
A KOtBu and ethyl acetate mediated efficient methodology has been developed for the acetylation of primary and secondary alcohols where ethyl acetate is the source of acetyl group. The reaction is fast, mild, efficient, and highly selective towards the primary alcohols.
- Singha, Raju,Ray, Jayanta K.
-
supporting information
p. 5395 - 5398
(2016/11/11)
-
- TiCl4/Et3N-Mediated Condensation of Acetate and Formate Esters: Direct Access to β-Alkoxy- and β-Aryloxyacrylates
-
A methodology to build (E)-β-alkoxy- and (E)-β-aryloxyacrylate moieties from acetate and formate esters promoted by the TiCl4/Et3N system is presented. The reaction is compatible with a broad range of structural skeletons and elapses through an unusual condensation pathway. Taking into account the obtained results, we propose a plausible mechanism involving a bimetallic titanium intermediate for this type of transformation.
- álvarez-Calero, José María,Jorge, Zacarías D.,Massanet, Guillermo M.
-
supporting information
p. 6344 - 6347
(2016/12/23)
-
- Proton-gradient-transfer acid complexes and their catalytic performance for the synthesis of geranyl acetate
-
Special proton-gradient-transfer acid complexes (PGTACs) in which the bonded protons are not equivalent and have gradients in transfer ability, acidity, and reactivity were reported. The acidity gradient of the protons gave the PGTACs excellent catalytic activity and selectivity in the esterification of terpenols. These PGTACs are “reaction-induced self-separation catalysts” and can be easily reused. The kinetics with PGTACs as catalyst in the esterification of geraniol were also studied for use in engineering design.
- Chen, Yongle,Ding, Shiya,Zheng, Wentao,Zhang, Yiyang,Wu, Youting,Hu, Xingbang
-
p. 2114 - 2121
(2017/01/16)
-
- Graphite oxide-catalyzed acetylation of alcohols and phenols
-
Graphite oxide (GO) was used as a catalyst for the reactions of alcohols and phenols with acetic anhydride. The acetates of primary and secondary alcohols were prepared in good to excellent yields in short reaction time under mild conditions. Electron deficient phenols could be converted to the corresponding acetates steadily. As an efficient catalyst, GO is easily available, cheap, moderately toxic and weakly acidic.
- Liu, Yuan-Yuan,Qi, Jun-Mei,Bai, Li-Sha,Xu, Yue-Long,Ma, Ning,Sun, Fei-Fei
-
supporting information
p. 726 - 730
(2016/05/19)
-
- Efficient O-Acylation of Alcohols and Phenol Using Cp2TiCl as a Reaction Promoter
-
A method has been developed for the conversion of primary, secondary, and tertiary alcohols, and phenol, into the corresponding esters at room temperature. The method uses a titanium(III) species generated from a substoichiometric amount of titanocene dichloride together with manganese(0) as a reductant, as well as methylene diiodide. It involves a transesterification from an ethyl ester, or a reaction with an acyl chloride. A radical mechanism is proposed for these transformations.
- Durán-Pe?a, María Jesús,Botubol-Ares, José Manuel,Hanson, James R.,Hernández-Galán, Rosario,Collado, Isidro G.
-
supporting information
p. 3584 - 3591
(2016/07/28)
-
- A process for the preparation of acetate
-
The invention relates to an acetate preparation method. The method comprises the following steps: carrying out a contact reaction of sec-butyl acetate and alcohol in the presence of an ester exchange catalyst under an ester exchange reaction condition, adding products obtained after the contact reaction into a separation tower, controlling the tower top temperature to separate unreacted sec-butyl acetate and sec-butyl alcohol generated after the reaction from the tower top, and carrying out normal-pressure or reduced-pressure flash evaporation to separate acetate generated after the reaction from a tower bottom fraction, wherein the alcohol is alcohol having a general formula of R(OH)n and/or polyol alkylether having at least one hydroxy group, R is a C5-C20 n-valence alkyl group, a C5-C20 n-valence alkenyl group, a C5-C12 n-valence cycloalkyl group or a C7-C20 n-valence aryl group, and n is an integer in a range of 1-5. The method has the advantages of high conversion rate of the alcohol as a reaction raw material, and high acetate selectivity.
- -
-
Paragraph 0043; 0044; 0045; 0046
(2017/01/26)
-
- Palladium-catalyzed Mizoroki-Heck-type reactions of [Ph2SRfn][OTf] with alkenes at room temperature
-
The first Pd-catalyzed Mizoroki-Heck-type reaction of [Ph2SRfn][OTf] with alkenes is described. The reaction of [Ph2SRfn][OTf] (Rfn = CF3, CH2CF3) with alkenes in the presence of 10 mol% Pd[P(t-Bu)3]2 and TsOH at room temperature provided the corresponding phenylation products in good to high yields. The bases that benefit the traditional Mizoroki-Heck reactions severely inhibited the transformation with [Ph2SRfn][OTf], whereas acids significantly improved the reaction. This protocol supplies a new class of cross-coupling partners for Mizoroki-Heck-type reactions and gains important insights into the reactivity of phenylsulfonium salts either with or without fluorine-containing alkyl groups as the promising phenylation reagents in organic synthesis.
- Wang, Shi-Meng,Song, Hai-Xia,Wang, Xiao-Yan,Liu, Nan,Qin, Hua-Li,Zhang, Cheng-Pan
-
supporting information
p. 11893 - 11896
(2016/10/09)
-
- Sol–Gel Immobilized N-Heterocyclic Carbene Gold Complex as a Recyclable Catalyst for the Rearrangement of Allylic Esters and the Cycloisomerization of γ-Alkynoic Acids
-
The synthesis of a bis-silylated (NHC)AuCl (NHC=N-heterocyclic carbene) complex and the formation of a hybrid silica material by the sol–gel process by cogelification with tetraethylorthosilicate under fluoride catalysis are described. This material was characterized by using 29Si solid-state NMR spectroscopy, N2 sorption measurements, electron microscopy, and elemental analysis. It was tested as a reusable catalyst in the rearrangement of allylic esters in conjunction with a silver salt under microwave conditions and it displayed a much better performance than a homogeneous analogue. This catalyst is active and recyclable in the cycloisomerization of γ-alkynoic acids to five-membered enol-lactones at room temperature in two reaction media, a toluene/water biphasic system and a deep eutectic solvent.
- Ferré, Meritxell,Catto?n, Xavier,Wong Chi Man, Michel,Pleixats, Roser
-
p. 2824 - 2831
(2016/09/13)
-
- Titanocene(III) chloride mediated radical-induced opening of monosubstituted epoxy acetates for the synthesis of primary allylic alcohols
-
A simple and efficient method for the synthesis of primary allylic alcohols from monosubstituted epoxy acetates has been developed using titanocene(III) chloride mediated epoxide ring opening via acetate elimination.
- Chakraborty,Mandal,Roy
-
p. 893 - 901
(2015/08/18)
-
- Chemo-, regio-, and stereoselective Heck-Matsuda arylation of allylic alcohols under mild conditions
-
Heck arylation with allylic alcohol is extremely challenging due to chemo-, regio-, and stereoselective scrambling. Here we report a mild protocol for the alcohol selective β- and α-arylation of allylic and cinnamyl alcohols respectively with aryldiazonium salts. The steric and electronic parameters of the alkene play a prominent role in the regioselectivity.
- Chaudhari, Tohasib Yusub,Hossian, Asik,Manna, Manash Kumar,Jana, Ranjan
-
supporting information
p. 4841 - 4845
(2015/05/05)
-
- Synthesis of lipase nano-bio-conjugates as an efficient biocatalyst: Characterization and activity-stability studies with potential biocatalytic applications
-
In the present study, we have synthesized lipase-nano-bio-conjugates via immobilization of various lipases on multiwall carbon nano-tubes (MCNT), in order to construct an efficient and recyclable biocatalytic system. In a screening study lipase Pseudomonas fluorescens (PFL) acted as an efficient biocatalyst (lipase-nano-bio-conjugates) which showed higher retention of lipase activity and protein loading. Consequently the immobilization support : lipase (MCNT : PFL) composition was screened in which MCNT : PFL (2 : 1) was calculated as a robust biocatalyst composition which showed higher activity retention and protein loading. This nano-bio-conjugate was then characterized in detail with physical and biochemical techniques using SEM, TEM, FTIR, Km, Vmax, catalytic efficiency and (%) water content analysis. This developed biocatalyst was further used for practical biocatalytic applications such as O-acylation reactions. Various reaction parameters were optimized in detail like reactant molar ratio (2 : 3.5), solvent, MCNT : PFL biocatalyst amount (36 mg), temperature (50°C) etc. The developed biocatalytic protocol was then extended to synthesize several (twenty-two) industrially important acylated moieties with an excellent yield, these products are well characterized by 1HNMR, 13CNMR and GCMS analysis. Moreover in the present study, we have reviewed the potential industrial applications of various synthesized compounds. Also, we have studied the thermodynamic aspect which demonstrated more feasibility of use of immobilized MCNT : PFL lipase over free lipase. Interestingly, immobilized MCNT : PFL lipase showed 2.3 fold higher catalytic activity than free PFL. Besides this, the biocatalyst was efficiently recycled for up to five cycles. Thus the present protocol demonstrated, (i) synthesis of nano-bio-conjugates as a bio-catalyst, (ii) detailed physical-biochemical characterization of nano-bio-conjugates, (iii) optimization of the biocatalytic protocol (iv) practical biocatalytic applications along with a mechanistic study (v) a thermodynamic feasibility study and (vi) recyclability study. 2015
- Badgujar, Kirtikumar Chandulal,Sasaki, Takehiko,Bhanage, Bhalchandra Mahadeo
-
p. 55238 - 55251
(2015/07/07)
-
- Selenium-catalyzed C(sp3)-H acyloxylation: Application in the expedient synthesis of isobenzofuranones
-
Oxidative Se-catalyzed C(sp3)-H bond acyloxylation has been used to construct a diverse array of isobenzofuranones from simple ortho-allyl benzoic acid derivatives. The synthetic procedure employs mild reaction conditions and gives high chemoselectivity enabled by an inexpensive organodiselane catalyst. The presented approach offers a new synthetic pathway toward the core structures of phthalide natural products.
- Kr?tzschmar, Felix,Kassel, Martin,Delony, Daniel,Breder, Alexander
-
supporting information
p. 7030 - 7034
(2015/05/05)
-