- Cis and trans radicals generated in helical poly(propargyl acetate)s prepared using a [Rh(norbornadiene)Cl]2 catalyst
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The poly(propargyl acetate) (A) having a helical cis-transoid structure was stereospecifically prepared using the Rh complex catalyst, [Rh(norbornadiene) Cl]2, in MeOH or NEt3 solvent at 0 and 40 °C in moderate yield. Electron spin resonance (ESR) analysis of the polymer revealed the formation of the cis (B) and trans (C) radicals which were produced through the thermal rotational scission of the helical cis CC bonds in the main-chain during the polymerization. The spatial and geometrical structure was successfully deduced using the two analogues' polymers in which either methyl or methylene group is deuterated, by the aide of computer simulation of the observed ESR spectra together with the calculation of spin density of the two radicals.
- Yoshida, Yoshiaki,Mawatari, Yasuteru,Seki, Chigusa,Hiraoki, Toshifumi,Matsuyama, Haruo,Tabata, Masayoshi
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Read Online
- Simple One-Pot Preparation of 1,2-Diacetoxy-2-propene. A Convenient Precursor of 1-Acetoxy-3-chloro-2-propanone
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From a neat mixture of acetic acid and propargyl alcohol, 1,2-diacetoxy-2-propene was prepared by successive treatment with an acid catalyst and a Ru catalyst in one-pot procedure.The product was a convenient precursor of 1-acetoxy-3-chloro-2-propanone.
- Sakai, Kunikazu,Kondo, Kiyosi
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Read Online
- Enantioselective Addition of Alkynyl Esters and Ethers to Aldehydes Catalyzed by a Cyclopropyl Amino Alcohol Based Zinc Catalyst
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A novel and highly enantioselective synthesis of hydroxyalkynyl esters and ethers through the asymmetric addition of alkynyl esters or ethers to aldehydes promoted by a cyclopropyl amino alcohol based zinc catalyst has been developed. The method afforded a library of new enantioenriched hydroxyalkynol esters and ethers (up to 93percent yield; 95percent ee), and it was compatible with a broad range of functional groups. Moreover, it could be used in the synthesis of carbon-chain-elongated enantioenriched hydroxyalkynol esters and (2 R,5 R)-musclide-A1, a cardiotonic potentiating principle from musk.
- Bian, Qinghua,Li, Fengqi,Li, Shuoning,Ma, Sijie,Walsh, Patrick J.,Wang, Lifeng,Wang, Min,Zhong, Jiangchun,Zhou, Yun
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supporting information
p. 60 - 64
(2019/12/30)
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- Synthesis of Cyclopenta[b]indoles via a Formal [3+2] Cyclization of N-Sulfonyl-1,2,3-triazoles and Indoles
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Annulation of benzoxy-tethered N-sulfonyl-1,2,3-triazoles and indoles has been developed in this paper, providing an efficient and convenient access to valuable cyclopenta[b]indoles in moderate to good yields. α,β-Unsaturated imine, which generated in situ from denitrogenation and 1,2-OBz migration of triazole, provided three carbons for the formal [3+2] cyclization reaction for the first time. (Figure presented.).
- Duan, Shengguo,Zhang, Wan,Hu, Yuntong,Xu, Ze-Feng,Li, Chuan-Ying
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supporting information
p. 3570 - 3575
(2020/08/05)
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- Neighboring Carbonyl Group Assisted Oxyacetoxylation of Propargylic Carboxylates with Retention of Chirality under Metal Free Condition
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A metal-free oxyacetoxylation method of primary, secondary and tertiary propargylic carboxylates with retention of chirality was presented. The reaction proceeds through the intramolecular nucleophilic attack of the neighboring carbonyl group on an alkynyliodonium intermediate. The process is general with broad substrate scope and is amenable for application to a variety of propargyl carboxylates including those obtained from natural products. Insight into the mechanistic pathway by isotopic labelling (using H2O18 and D2O) and controlled experiments confirmed. (Figure presented.).
- Pradhan, Tapas R.,Mohapatra, Debendra K.
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supporting information
p. 3605 - 3611
(2019/07/04)
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- Rhodium-catalysed synthesis of fused pyrimidine derivatives employing N-sulfonyl-1,2,3-triazoles as a 1-aza-[4C] synthon
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A new synthetic application of N-sulfonyl-1,2,3-triazoles acting as a 1-aza-[4C] synthon via the 1,2-shift reaction of an α-imine rhodium carbene was developed for the synthesis of fused pyrimidine derivatives. The high reactivity of the strained three-me
- Xu, Ze-Feng,An, Yuehui,Chen, Yidian,Duan, Shengguo
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supporting information
p. 1849 - 1853
(2019/06/20)
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- Deep eutectic solvent choline chloride·2CrCl3·6H2O: An efficient catalyst for esterification of formic and acetic acid at room temperature
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A highly efficient and selective method for esterification of formic and acetic acid with alcohols has been achieved at room temperature, with the choline chloride (ChCl)/chromium(iii) chloride hexahydrate (CrCl3·6H2O) deep eutectic solvent as a catalyst. High yields and good selectivities of organic esters are obtained using DES [ChCl][CrCl3·6H2O]2 with the molar ratio 5:1 (carboxylic acids:alcohols) at room temperature in 24 h. The ease of recovery and reusability of DES with high catalytic activity makes this method efficient and practical.
- Cao, Jin,Qi, Bin,Liu, Jun,Shang, Yuhan,Liu, Huiwen,Wang, Wenjing,Lv, Jia,Chen, Zhiyan,Zhang, Haibo,Zhou, Xiaohai
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p. 21612 - 21616
(2016/03/08)
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- PROCESS FOR THE PREPARATION OF HYPERPOLARIZED CARBOXYLATE COMPOUNDS
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The present invention relates to a process for the preparation of aqueous solutions of [1-13C]-hyperpolarized carboxylate containing molecules of diagnostic interest that comprises parahydrogenating with molecular parahydrogen unsaturated alkenyl or alkynyl esters of the concerned 13C- carboxylate molecules.
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Page/Page column 34-35
(2015/05/19)
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- Synthesis of polyfunctional triethoxysilanes by 'click silylation'
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The copper-catalyzed 'click silylation' has been exploited for the chemical modification of γ-azidopropyltriethoxysilane (AzPTES) with a wide range of terminal alkynes (1a-1v) in a one-pot operation. The novel 1,2,3-triazole-triethoxysilane derivatives (2a-2v) were synthesized by this procedure and comprehensively characterized by IR spectra, 1H and 13C NMR, and HRMS studies.
- Singh, Gurjaspreet,Mangat, Satinderpal Singh,Singh, Jandeep,Arora, Aanchal,Sharma, Ramesh K.
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supporting information
p. 903 - 909
(2015/03/03)
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- Vitamin B1 supported on silica-encapsulated γ-Fe 2O3 nanoparticles: Design, characterization and application as a greener biocatalyst for highly efficient acylation
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A new magnetic catalyst was synthesized by the immobilization of vitamin B1 (thiamine hydrochloride) on the surface of silica-encapsulated γ-Fe2O3 nanoparticles. Its capability was evaluated in the acylation of alcohols and phenols with acetic anhydride under solvent-free conditions and afforded the desired products in high yield. This novel magnetic organocatalyst could be separated from the reaction vessel by use of an external magnet and recovered 5 times without a significant loss of its activity. The amount of loaded vitamin B1 on the silica-encapsulated γ-Fe2O3 was assigned by TGA and confirmed by back titration. Availability, cheapness and low toxicity are reasons associated with the utilization of vitamin B1 as a catalyst. The catalyst has been characterized by FT-IR, XRD, SEM, VSM and TG/DTA. The Royal Society of Chemistry.
- Azizi, Kobra,Heydari, Akbar
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p. 8812 - 8816
(2014/03/21)
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- Synthesis of polyfunctional triethoxysilanes by 'click silylation'
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The copper-catalyzed 'click silylation' has been exploited for the chemical modification of γ-azidopropyltriethoxysilane (AzPTES) with a wide range of terminal alkynes (1a-1v) in a one-pot operation. The novel 1,2,3-triazole-triethoxysilane derivatives (2a-2v) were synthesized by this procedure and comprehensively characterized by IR spectra, 1H and 13C NMR, and HRMS studies.
- Singh, Gurjaspreet,Mangat, Satinderpal Singh,Singh, Jandeep,Arora, Aanchal,Sharma, Ramesh K.
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supporting information
p. 903 - 909
(2014/02/14)
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- Efficient acetylation of alcohols and phenols catalyzed by recyclable lithium bis(perfluoroalkylsulfonyl)imide
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An efficient acetylation of alcohols and phenols catalyzed by lithium bis(perfluoroalkylsulfonyl)-imide was developed. This acetylation features good yields, mild reaction condtions, and simple workup procedures. Furthermore, the catalyst bearing a long perfluoroalkyl chain is recoverable and readily reusable without losing any activity. Copyright
- Li, Guilong,Zhao, Gang
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p. 34 - 43,10
(2020/08/24)
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- Ring-opening metathesis polymerization with the second generation hoveyda-grubbs catalyst: An efficient approach toward high-purity functionalized macrocyclic oligo(cyclooctene)s
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Herein, we present a facile and general strategy to prepare functionalized macrocyclic oligo(cyclooctene)s (cOCOEs) in high purity and high yield by exploiting the ring-opening metathesis polymerization (ROMP) intramolecular backbiting process with the commercially available second generation Hoveyda-Grubbs (HG2) catalyst. In the first instance, ROMP of 5-acetyloxycyclooct-1-ene (ACOE) followed by efficient quenching and removal of the catalyst using an isocyanide derivative afforded macrocyclic oligo(5-acetyloxycyclooct-1-ene) (cOACOE) in high yield (95%), with a weight-average molecular weight (Mw) of 1.6 kDa and polydispersity index (PDI) of 1.6, as determined by gel permeation chromatography (GPC). The structure and purity of the macrocycles were confirmed by NMR spectroscopy and elemental analysis, which indicated the complete absence of end-groups. This was further supported by GPC-matrix assisted laser desorption ionization time-of-flight mass spectroscopy (GPC-MALDI ToF MS), which revealed the exclusive formation of macrocyclic derivatives composed of up to 45 repeat units. Complete removal of residual ruthenium from the macrocycles was confirmed by inductively coupled plasma atomic emission spectroscopy (ICP-AES). The same methodology was subsequently extended to the ROMP of 5-bromocyclooct-1-ene and 1,5-cyclooctadiene to prepare their macrocyclic derivatives, which were further derivatized to produce a library of functionalized macrocyclic oligo(cyclooctene)s. A comparative study using the second and third generation Grubbs catalysts in place of the HG2 catalyst for the polymerization of ACOE provided macrocycles contaminated with linear species, thus indicating that the bidendate benzylidene ligand of the Hoveyda-Grubbs catalyst plays an important role in the observed product distributions.
- Blencowe, Anton,Qiao, Greg G.
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supporting information
p. 5717 - 5725
(2013/05/21)
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- Tunable self-assembly of triazole-linked porphyrin-polymer conjugates
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The convergence of supramolecular chemistry and polymer science offers many powerful approaches for building functional nanostructures with well-defined dynamic behaviour. Herein we report the efficient "click" synthesis and self-assembly of AB2- and AB4-type multitopic porphyrin-polymer conjugates (PPCs). PPCs were prepared using the copper(I)-catalysed azide-alkyne cycloaddition (CuAAC) reaction, and consisted of linear polystyrene, poly(butyl acrylate), or poly(tert-butyl acrylate) arms attached to a zinc(II) porphyrin core via triazole linkages. We exploit the presence of the triazole groups obtained from CuAAC coupling to direct the self-assembly of the PPCs into short oligomers (2-6 units in length) via intermolecular porphyrinatozinc-triazole coordination. By altering the length and grafting density of the polymer arms, we demonstrate that the association constant of the porphyrinatozinc-triazole complex can be systematically tuned over two orders of magnitude. Self-assembly of the PPCs also resulted in a 6a K increase in the glass transition temperature of the bulk material compared to a non-assembling PPC. The modular synthesis and tunable self-assembly of the triazole-linked PPCs thus represents a powerful supramolecular platform for building functional nanostructured materials. Tunable building blocks: Triazole-linked porphyrin-polymer conjugates (PPCs) were prepared in high yield using the copper(I)-catalysed azide-alkyne cycloaddition (CuAAC) "click" reaction. The triazole groups were introduced from CuAAC coupling to guide the self-assembly of the PPCs into short oligomers (2-6 units in length) via intermolecular porphyrinatozinc-triazole coordination. Association constants of the PPCs could be tuned by altering the polymer microenvironment around the porphyrin core, thus presenting a modular platform for designing self-assembled porphyrin-polymer materials. Copyright
- Roberts, Derrick A.,Schmidt, Timothy W.,Crossley, Maxwell J.,Perrier, Sebastien
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supporting information
p. 12759 - 12770
(2013/10/01)
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- Iron (III) phosphate as a green and reusable catalyst promoted chemo selective acetylation of alcohols and phenols with acetic anhydride under solvent free conditions at room temperature
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Iron (III) phosphate was employed as an efficient catalyst for the chemo selective acetylation of alcohols and phenols under solvent free condition at room temperature and with high yields. Iron (III) phosphate is also a potential green catalyst due to solid intrinsically, reusable and with high catalytic activity.
- Behbahani,Farahani,Oskooie
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experimental part
p. 633 - 637
(2011/10/08)
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- Air-stable titanocene bis(perfluorooctanesulfonate) as a new catalyst for acylation of alcohols, phenols, thiols, and amines under solvent-free condition
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Air-stable titanocene bis(perfluorooctanesulfonate) [Cp2Ti(OSO2C8F17)2] that shows high Lewis acidity was prepared from Cp2TiCl2 and AgOSO2C8F17. The compound was characterized by different techniques, and examined as a catalyst for acylation reactions. It was found that using equimolar acetic anhydride as acetylating agent and under solvent-free condition, Cp2Ti(OSO2C8F17)2 exhibits high activity and selectivity in the acetylation of various alcohols, phenols, thiols, and amines. Also, good catalytic efficiency is observed in the acylation of 2-phenylethanol across various acylating reagents. The catalyst can be reused without loss of activity in a test of ten cycles. The Cp2Ti(OSO2C8F17)2 catalyst affords a simple, efficient and general method for the acylation of alcohols, phenols, thiols, and amines.
- Qiu, Renhua,Zhang, Guoping,Ren, Xiaofang,Xu, Xinhua,Yang, Ronghua,Luo, Shenglian,Yin, Shuangfeng
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experimental part
p. 1182 - 1188
(2010/06/13)
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- Mechanistic insights into Cu(I)-catalyzed azide-alkyne "click" cycloaddition monitored by real time infrared spectroscopy
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A designed ligand-accelerated Cu(I)-catalyzed cycloaddition (CuAAC) reaction was monitored for the first time by real time infrared analysis technique based on ATR-FTIR principles. Principal components analysis (PCA) and two-dimensional correlation spectr
- Sun, Shengtong,Wu, Peiyi
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experimental part
p. 8331 - 8336
(2011/02/17)
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- A heterogeneous cobalt(II) Salen complex as an efficient and reusable catalyst for acetylation of alcohols and phenols
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Acetylation of various alcohols and phenols was performed successfully using an immobilized cobalt(II) catalyst in high yield. The catalyst shows high thermal stability and was also recovered and reused at least 10 times without any considerable loss of activity.
- Rajabi, Fatemeh
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scheme or table
p. 395 - 397
(2009/05/07)
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- Selective acetylation of alcohols and amines with ethyl acetate in the presence of H6[PMo9V3O40] as the catalyst
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Acetylation of various alcohols and benzyl amine was tested in the presence of H6[PMo9V3O40], a mixed addenda heteropolyacid, in ethyl acetate under reflux condition. Phenols and anilines are not affected under the reaction conditions. Selective transestrification of alcohols can be achieved in the presence of phenol and aniline derivatives using this method. Springer-Verlag 2007.
- Heravi, Majid M.,Bakhtiari, Khadijeh,Javadi, Negar M.,Oskooie, Hossein A.,Bamoharram, Fatemeh F.
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p. 445 - 447
(2008/02/02)
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- Erbium(III) chloride: A very active acylation catalyst
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Erbium(iii) chloride is a powerful catalyst for the acylation of alcohols and phenols. The reaction works well for a large variety of simple and functionalized substrates by using different kinds of acidic anhydrides (Ac 2O, (EtCO)2O, (PriCO)2O, (Bu tCO)2O, and (CF3CO)2), without isomerization of chiral centres. Moreover, the catalyst can be easily recycled and reused without significant loss of activity. CSIRO 2007.
- Dalpozzo, Renato,De Nino, Antonio,Maiuolo, Loredana,Oliverio, Manuela,Procopio, Antonio,Russo, Beatrice,Tocci, Amedeo
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- Ruthenium(III) acetylacetonate [Ru(acac)3] -An efficient recyclable catalyst for the acetylation of phenols, alcohols, and amines under neat conditions
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A catalytic amount of ruthenium(III) acetylacetonate (2 mol%) [Ru(acac)3] enables solvent-free acetylation of phenols, alcohols, and amines at ambient temperature in good to excellent yields. Furthermore, the catalyst could be recovered and reused at least three times without a significant loss in yields.
- Varala, Ravi,Nasreen, Aayesha,Adapa, Srinivas R.
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p. 148 - 152
(2008/02/11)
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- Synthesis of N-propargylanabasine derivatives by the mannich reaction
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N-Propargylanabasine derivatives bearing various substituents at the carbon atom of the alkyne fragment were obtained by the reaction of anabasine hydrochloride with terminal alkynes and paraformaldehyde. The reaction proceeded with retention of the C(2) chiral center in anabasine fragment. The by-products of the reaction, including 1,3-diacetylene (the products of dimerization of alkynes) and conjugated vinylacetylenes (the rearrangement products of the Mannich adducts) were isolated and characterized.
- Mavrov,Zlotin
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p. 1637 - 1647
(2008/09/18)
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- CuSO4 as a mild, green, and efficient catalyst for the one-pot conversion of THP ethers to acetates
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An efficient direct conversion of THP ethers into the corresponding acetates was achieved with acetic anhydride in the presence of CuSO4 ? 5H2O as an available and green catalyst in high yields.
- Asadolah, Karim,Heravi, Majid M.
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p. 867 - 869
(2008/02/11)
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- A novel 3-nitrobenzeneboronic acid as an extremely mild and environmentally benign catalyst for the acetylation of alcohols under solvent-free conditions
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A novel 3-nitrobenzeneboronic acid is found to catalyse efficiently the acetylation of a wide range of alcohols as well as phenols with acetic anhydride in good to excellent yields at room temperature under solvent-free conditions. The reactions are clean and the catalyst is mild such that highly sensitive functional groups including oximes are stable to the reaction conditions.
- Tale,Adude
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p. 7263 - 7265
(2007/10/03)
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- A cheap, simple, and versatile method for acetylation of alcohols and phenols and selective deprotection of aromatic acetates under solvent-free condition
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Acyclic and cyclic acetates of various alcohols and phenols were obtained in excellent yields under mild reaction conditions in the presence of a catalytic amount of sodium hydroxide under solvent-free conditions and microwave irradiation. Selective deprotection of acetate group from the corresponding phenolic compounds was carried out in the presence of LiClO4· 2H2O. Copyright Taylor & Francis, Inc.
- Rajabi, Fatemeh,Saidi, Mohammad R.
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p. 483 - 491
(2007/10/03)
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- WATER SOLUBLE ESTERS OF [N-(4-AMINO-2-BUTYNYL)] WITH ANTICANCER ACTIVITY
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The present invention relates to water soluble esters of [N-(4-amino-2-butynyl)] or 4-(N-substituted amino)-2-butynyl-1-esters and methods for production of said esters and the use of the esters for treatment of cancer.
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Page/Page column 41; 42
(2008/06/13)
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- Facile catalyzed acylation of alcohols, phenols, amines and thiols based on ZrOCl2·8H2O and acetyl chloride in solution and in solvent-free conditions
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Acylation of heteroatoms (O, N and S) with acetyl chloride based on the use of a catalytic amount of the moisture stable, inexpensive ZrOCl 2?8H2O, proceeds efficiently producing the corresponding acylated products in excellent yields.
- Ghosh, Rina,Maiti, Swarupananda,Chakraborty, Arijit
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p. 147 - 151
(2007/10/03)
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- Zinc oxide (ZnO) as a new, highly efficient, and reusable catalyst for acylation of alcohols, phenols and amines under solvent free conditions
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Zinc oxide (ZnO) is a highly efficient catalyst for the acylation of a variety of alcohols, phenols and amines with acid chlorides or acid anhydrides under solvent free conditions. Primary, secondary, tertiary, allylic and benzylic alcohols, diols and phenols with electron donating or withdrawing substituents can be easily acylated in good to excellent yield.
- Hosseini Sarvari, Mona,Sharghi, Hashem
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p. 10903 - 10907
(2007/10/03)
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- Zirconiuni(IV) chloride as a new, highly efficient, and reusable catalyst for acetylation of phenols, thiols, amines, and alcohols under solvent-free conditions
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Zirconium(IV) chloride has been found to be a new, highly efficient, and reusable catalyst for acetylation of structurally diverse phenols, thiols, amines, and alcohols under solvent-free condtions. Acetylation of sterically hindered and electron deficient phenols is achieved in excellent yields with stoichiometric amounts of Ac2O at room temperature. Acid-sensitive alcohols undergo acetylation with excellent chemoselectivity without competitive side reactions such as dehydration or rearrangement. The mild Lewis acid property of the catalyst enables the acetylation to be carried out with optically active substrates without any detrimental effect on the optical purity.
- Chakraborti, Asit K.,Gulhane, Rajesh
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p. 627 - 630
(2007/10/03)
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- Copper(II) Tetrafluoroborate-Catalyzed Acetylation of Phenols, Thiols, Alcohols, and Amines
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Copper(II) tetrafluoroborate efficiently catalyzes acetylation of structurally diverse phenols, alcohols, thiols, and amines with stoichiometric amounts of Ac2O under solvent-free conditions at room temperature. Acid-sensitive alcohols are smoothly acetylated without competitive side reactions. The reaction is influenced by the steric and electronic factors associated with the substrate as well as the anhydride. Acetylation of a sterically hindered substrate requires excess of anhydride and longer time. Acylation with less electrophilic anhydrides affords poor to moderate yields.
- Chakraborti, Asit K.,Gulhane, Rajesh,Shivani
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p. 111 - 115
(2007/10/03)
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- Erbium(III) triflate as an extremely active acylation catalyst
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Erbium(III) triflate is a powerful catalyst for the acylation of alcohols and phenols. The reaction works well for a large variety of simple and functionalized substrates by using different kinds of acidic anhydrides {Ac 2O, (EtCO)2O, [(CH3)3CO] 2O, Bz2O, and (CF3CO)2O} without isomerisation of chiral centres. Moreover, the catalyst can be easily recycled and reused without significant loss of activity.
- Procopio, Antonio,Dalpozzo, Renato,De Nino, Antonio,Maiuolo, Loredana,Russo, Beatrice,Sindona, Giovanni
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p. 1465 - 1470
(2007/10/03)
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- Reactions on a Solid Surface. A Simple, Economical, and Efficient Acylation of Alcohols, Amines over Al2O3
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Al2O3 brings about a rapid acylation of a range of alcohols and amines with acid chlorides and acid anhydrides, respectively. Amines are easily Boc- and Cbz-protected on reaction with Boc-anhydride and Cbz-Cl, respectively. The acylation of phenols is slow enough to allow chemoselective acylation of alcohols and amines in the presence of phenols.
- Yadav, Veejendra K.,Babu, K. Ganesh
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p. 577 - 580
(2007/10/03)
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- Facile catalyzed acylation of heteroatoms using BiCl3 generated in situ from the procatalyst BiOCl and acetyl chloride
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Acylation of a variety of alcohols, phenols, aliphatic and aromatic amines, a thiol and a thiophenol proceeds efficiently using BiCl3 generated in situ from the procatalyst BiOCl and acetyl chloride in a solvent or under solventless conditions, furnishing the corresponding acylated derivatives in very good to excellent yields.
- Ghosh, Rina,Maiti, Swarupananda,Chakraborty, Arijit
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p. 6775 - 6778
(2007/10/03)
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- Fluoroboric acid adsorbed on silica gel as a new and efficient catalyst for acylation of phenols, thiols, alcohols, and amines
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Fluoroboric acid supported on silica gel efficiently catalyzes acylation of structurally diverse phenols, alcohols, thiols, and amines under solvent free conditions. Acid-sensitive alcohols are smoothly acylated without competitive side reactions.
- Chakraborti, Asit K.,Gulhane, Rajesh
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p. 3521 - 3525
(2007/10/03)
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- Indium(III) chloride as a new, highly efficient, and versatile catalyst for acylation of phenols, thiols, alcohols, and amines
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Indium(III) chloride efficiently catalyses the acylation of structurally diverse phenols, alcohols, thiols, and amines under solvent free conditions. Acid sensitive alcohols are smoothly acylated without competitive side reactions. Acylation of 2-hydroxynaphthalene is carried out with carboxylic acids adopting the mixed anhydride protocol using trifluoroacetic anhydride.
- Chakraborti, Asit K.,Gulhane, Rajesh
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p. 6749 - 6753
(2007/10/03)
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- Electrostatic catalysis by ionic aggregates: Scope and limitations of Mg(ClO4)2 as acylation catalyst
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Alkali and alkaline earth metal perchlorates exhibit electrostatic catalysis in the activation of anhydrides for the acylation reaction. Perchlorates with higher values of the charge-size function of the metal ion exhibit better catalytic activity following the order Mg(ClO4) 2>Ba(ClO4)2>LiClO4. Acylation of structurally diverse phenols, thiols, alcohols, and amines have been carried out with stoichiometric amounts of anhydride at room temperature under solvent free conditions in the presence of catalytic amount of Mg(ClO4) 2. Sterically hindered and electron deficient phenols are efficiently acylated. Acylation with sterically hindered anhydrides such as iso-butyric, pivalic, and benzoic anhydrides are carried out with phenols and alcohols in excellent yields. Acid-sensitive alcohols are acylated in excellent yields without any competitive side reactions.
- Chakraborti, Asit K.,Sharma, Lalima,Gulhane, Rajesh,Shivani
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p. 7661 - 7668
(2007/10/03)
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- Perchloric acid adsorbed on silica gel as a new, highly efficient, and versatile catalyst for acetylation of phenols, thiols, alcohols, and amines
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Perchloric acid adsorbed on silica gel efficiently catalyses acetylation of structurally diverse phenols, alcohols, thiols, and amines under solvent free conditions.
- Chakraborti, Asit K.,Gulhane, Rajesh
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p. 1896 - 1897
(2007/10/03)
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- Highly efficient and versatile acetylation of alcohols catalyzed by cerium(III) triflate
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Cerium(III) triflate is a powerful catalyst for the acetylation of alcohols. The reaction works well for a large variety of simple and functionalized alcohols, without isomerisation of chiral centres. Changes of hydroxyl protective groups are possible in a one-pot procedure. The catalyst can be easily recycled.
- Dalpozzo, Renato,De Nino, Antonio,Maiuolo, Loredana,Procopio, Antonio,Nardi, Monica,Bartoli, Giuseppe,Romeo, Roberto
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p. 5621 - 5624
(2007/10/03)
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- Bismuth Oxide Perchlorate as a Highly Efficient Catalyst for Heteroatom Acylation under Solvent-Free Conditions
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Bismuth oxide perchlorate efficiently catalyzes the acetylation of structurally diverse phenols, alcohols, thiols, and amines under solvent free conditions. Sterically hindered and electron deficient phenols are acetylated in excellent yields with stoichiometric amounts of Ac2O at room temperature. Acylation of acid-sensitive alcohols is carried out efficiently without competitive side reactions. Optically active substrates are acetylated without any detrimental effect on the optical purity.
- Chakraborti, Asit K.,Gulhane, Rajesh,Shivani
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p. 1805 - 1808
(2007/10/03)
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- Lithium perchlorate catalyzed acetylation of alcohols under mild reaction conditions
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Lithium perchlorate is found to efficiently catalyze the acetylation of alcohols and phenols with acetic anhydride in good to excellent yields.
- Nakae,Kusaki,Sato
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p. 1584 - 1586
(2007/10/03)
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- Highly selective one-pot conversion of THP and MOM ethers to acetates by indium triiodide-catalysed deprotection and subsequent transesterification by ethyl acetate
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The chemoselective one-pot conversion of tetrahydropyranyl (THP) and methoxymethyl (MOM) ethers of primary alcohols to the corresponding acetates was presented. It was done using indium triiodide-catalysed deprotection and subsequent acetylation by ethyl acetate through a transesterification process. The advantages offered by the method included operational simplicity, 'green' methodology involving no toxic or hazardous chemicals and high yield.
- Ranu, Brindaban C.,Hajra, Alakananda
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p. 2262 - 2265
(2007/10/03)
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- Indium triiodide catalysed one-step conversion of tetrahydropyranyl ethers to acetates with high selectivity
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Chemoselective one-step conversion of tetrahydropyranyl ethers of primary alcohols to corresponding acetates was carried out. The reaction occurred through an indium triiodide catalyzed transesterification process in ethyl acetate. The method provided advantages such as operational simplicity, acceptable reaction conditions to acid-sensitive functional groups and good yield.
- Ranu, Brindaban C.,Hajra, Alakananda
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p. 355 - 357
(2007/10/03)
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- Highly selective acylation of alcohols and amines by an indium triiodide-catalysed transesterification process
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A very simple method has been developed for the acylation of alcohols and amines by ethyl acetate through an indium triiodide-catalysed transesterification process. Using this method acylation of a primary OH group in the presence of secondary and phenolic OH groups, and of a primary NH2 in the presence of secondary NH and primary OH have been achieved with high selectivity. The Royal Society of Chemistry 2000.
- Ranu, Brindaban C.,Dutta, Pinak,Sarkar, Arunkanti
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p. 2223 - 2225
(2007/10/03)
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- HZSM-5-zeolite as remarkable and reusable catalyst for the direct acetylation of alcohols and phenols under solvent-free conditions
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HZSM-5 zeolite catalyze the acetylation of alcohols and phenols with acetic anhydride under solventless system. The catalyst can be recycled with no activity loss.
- Heravi, Majid M.,Tajbakhsh, Mahmood,Mohajerani, Bagher,Ghassemzadeh, Mitra
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p. 859 - 860
(2007/10/03)
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- Zeolite HSZ-360 as a new reusable catalyst for the direct acetylation of alcohols and phenols under solventless conditions
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Alcohols and phenols were efficiently acylated with acetic anhydride without solvent over zeolite HSZ-360. The catalyst can be reused with no activity loss.
- Ballini, Roberto,Bosica, Giovanna,Carloni, Silvia,Ciaralli, Lara,Maggi, Raimondo,Sartori, Giovanni
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p. 6049 - 6052
(2007/10/03)
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- Selective dimerization by a radical chain reaction in γ-irradiated crystals of 1,3-bis(3-acetoxyprop-1-ynyl)-4-methoxy-6-methylbenzene
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A single dimer is formed by a radical chain reaction upon γ-irradiation of 1,3-bis(3-acetoxyprop-1-ynyl)-4-methoxy-6-methylbenzene (1) crystals, sealed in a glass ampoule under vacuum at room temperature. The dimerization is initiated by the addition of t
- Yamamoto, Yukio,Ueda, Takashi,Kanehisa, Nobuko,Miyawaki, Keiichi,Takai, Yoshio,Tagawa, Seiichi,Sawada, Masami,Kai, Yasushi
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p. 743 - 747
(2007/10/03)
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- An Efficient and Selective Pallladium-catalysed Oxidative Dicarbonylation of Akynes to Alkyl- or Aryl-maleic Esters
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Terminal alkyne dicarbonylation can be readily effected under mild conditions by treating alkynes with carbon monoxide and alcohols or water at 25-80 deg C in the presence of PdI2, KI and air, with unprecedented catalytic efficiency.Dicarbonylation products are mainly maleic esters or acids and their ring-chain tautomers.The latter are formed to a large extent at room temperature.Reaction pathways are discussed.
- Gabriele, Bartolo,Costa, Mirco,Salerno, Giuseppe,Chiusoli, Gian Paolo
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- Cyclization Reactions of Molybdenum and Chromium Carbene Complexes with 1,6- and 1,7-Enynes: Effect of Tether Length and Composition
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It has been observed that the reaction of 1,6- and 1,7-enynes with pentacarbonyl(butylmethoxycarbene)molybdenum(0) (18) produces vinylcyclopropanes in good to excellent yield.A systematic investigation into the factors which govern the success of these cyclizations has been performed.Chromium carbene complexes also lead to the formation of vinylcyclopropanes but in significantly lower yields.When the pathway to vinylcyclopropanes is not followed, a number of other distinct types of products are obtained.The pathways leading to these various products are discussed and compared.
- Harvey, Daniel F.,Lund, Kevin P.,Neil, David A.
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p. 8424 - 8434
(2007/10/02)
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