- REINVESTIGATION OF THE SYNTHETIC REACTION OF DIMETHYLAMINO-1,3-INDANDIONE.
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One step preparation of dimethylamino-1,3-indandione (1) from salicyladehyde with glycine betaine was reinvestigated. Reaction conditions to give the best yield of 1, characterization of a minor product (2-acetoxybenzylidene diacetate), and reaction pathw
- Ito,Abe,Sasaki,Misono
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- The studies on chemoselective promiscuous activity of hydrolases on acylals transformations
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Chemoselective, mild and convenient protocol for the hydrolysis of the synthetically relevant acylals via promiscuous enzyme-catalyzed hydrolysis has been developed. It has been shown that promiscuous activity of the used hydrolases dominates their native activity related with carboxylic esters hydrolysis. The main advantage of the present methodology is that it can be conducted under neutral conditions at room temperature. Moreover, complete deprotection of acylals takes place within 10–20 min. Developed protocol can be used with compounds having a variety of hydrolytic labile groups since the cleavage is proceeded under neutral conditions and occurs exclusively on acylal moiety. Further this protocol was extended by the tandem Passerini multicomponent reaction leading to the α-acetoxy amides using acylals as the surrogates of the carbonyl components to P-MCR.
- Koszelewski, Dominik,Ostaszewski, Ryszard
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- SiO2@FeSO4 nano composite as nanocatalyst for the green synthesis 1,1-diacetates from aldehydes under solvent-free conditions
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Aldehydes compounds selective converted to 1,1-diacetates as protective reagent with SiO2@FeSO4 nano composite as effective nano catalyst at room temperature under solvent-free condition and acetic anhydride (Ac2O) as acet
- KarimKoshteh, Mostafa,Bagheri, Marziyeh,Zeynizadeh, Behzad
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p. 2780 - 2783
(2016/07/12)
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- Green procedures for the chemoselective synthesis of acylals and their cleavage promoted by recoverable sulfonic acid based nanoporous carbon (CMK-5-SO3H)
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A selective synthesis of gem-diacetates from the reaction of aldehydes and acetic anhydride in the presence of recyclable nanoporous solid sulfonic acid (CMK-5-SO3H) under solvent-free reaction conditions is reported. The catalyst was also found to be highly active for deprotection of resulting acylals in water. [Figure not available: see fulltext.]
- Zareyee, Daryoush,Mirzajanzadeh, Ehsan,Khalilzadeh, Mohammad Ali
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p. 1229 - 1234
(2015/10/06)
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- Poly(4-vinylpyridinium) perchlorate as an efficient solid acid catalyst for the chemoselective preparation of 1,1-diacetates from aldehydes under solvent-free conditions
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Poly(4-vinylpyridinium) perchlorate has been used as a supported, recyclable, environmentally-benign catalyst for the formation of acylals from aliphatic and aromatic aldehydes in good to excellent yields under solvent-free conditions. Notably, the reaction conditions were tolerant of ketones. This methodology offers several distinct advantages, including its operational simplicity and high product yield, as well as being green in terms of avoiding the use of toxic catalysts and solvents. Furthermore, the catalyst can be recovered and reused several times without any loss in its activity.
- Khaligh, Nader Ghaffari
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p. 329 - 334
(2014/04/03)
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- Ultrasound assisted the chemoselective 1,1-diacetate protection and deprotection of aldehydes catalyzed by poly(4-vinylpyridinium)hydrogen sulfate salt as a eco-benign, efficient and reusable solid acid catalyst
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Poly(4-vinylpyridinium) hydrogen sulfate solid acid was found to be efficient catalyst for preparation of 1,1-diacetate using ultrasound irradiation at ambient temperature and neat condition. Deprotection of the resulting 1,1-diacetates were achieved using the same catalyst in methanol solvent under ultrasound irradiation at room temperature. This new method consistently has the advantage of excellent yields and short reaction times. Utilization of solvent free, simple reaction conditions, isolation, and purification makes this manipulation very interesting from an economic and environmental perspective. Further, the catalyst can be reused and recovered for several times.
- Khaligh, Nader Ghaffari,Shirini, Farhad
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- Solvent-free catalytic preparation of 1,1-diacetates using a silica-supported functional ionic liquid as catalyst
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An efficient and convenient preparation of acylals from aldehydes and acetic anhydride, under solvent-free conditions, in the presence of a silica-supported functional ionic liquid, Si-[SbSipim][PF6], is reported. Si-[SbSipim][PF6] acts as a catalyst and can be recovered and reused four times without apparent loss of its catalytic activity.
- Kang, Li Q.,Cai, Yue Q.,Cheng, Lin
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p. 247 - 249
(2013/07/27)
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- A rapid, convenient and chemoselective synthesis of acylals from aldehydes catalyzed by reusable nano-ordered MCM-41-SO3H
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Acylals were prepared by direct condensation of aldehydes with acetic anhydride using nano-ordered MCM-41-SO3H as a heterogeneous catalyst under solvent-free conditions at room temperature in a very short reaction time and excellent yields. The catalyst is recyclable, non-toxic, neither air nor moisture sensitive, and easy to handle. High chemoselectivity toward aldehydes in the presence of ketones is another advantage of the present method which provides selective protection of aldehydes in their mixtures with ketones.
- Tourani, Hesam,Naimi-Jamal, Mohammad Reza,Dekamin, Mohammad Ghorban,Amirnejad, Meysam
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p. 1072 - 1076
(2013/02/22)
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- Introduction of N-sulfonic acid poly(4-vinylpyridinum) chloride as an efficient and reusable catalyst for the chemoselective 1,1-diacetate protection and deprotection of aldehydes
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N-sulfonic acid poly(4-vinylpyridinium) chloride is easily prepared by the reaction of poly(4-vinylpyridine) with neat chlorosulfonic acid. This reagent can be used as an efficient catalyst for the preparation of 1,1-diacetates at room temperature and neat condition. Deprotection of the resulting 1,1-diacetates can also be achieved using the same catalyst in methanol. This new method consistently has the advantages of excellent yields and short reaction times. Further, the catalyst can be reused and recovered for several times.
- Shirini, Farhad,Jolodar, Omid Goli
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experimental part
p. 61 - 69
(2012/04/17)
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- Ultrasound-assisted synthesis of acylals catalyzed by stannum (IV) phosphomolybdate under solvent-free condition
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An efficient method for the synthesis of acylals from different aldehydes and acetic anhydride in the presence of Keggin-type stannum (IV) phosphomolybdate under ultrasound irradiation at room temperature was achieved. This method provides a new and efficient protocol in terms of cost effective of catalyst, a wide scope of substrates, and simple work-up procedure.
- Ai, Hong Mei,Liu, Qing
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experimental part
p. 299 - 301
(2012/07/17)
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- Polystyrene-supported, Al(OTf)3-catalyzed chemoselective synthesis of acylals from aldehydes
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Cross-linked polystyrene-supported aluminium triflate [Ps-Al(OTf)3] has been shown to be a mild, efficient, and chemoselective heterogeneous Lewis acid catalyst for acetylation of aldehydes with acetic anhydride. The catalyst can be recovered simply and reused efficiently at least five times without any noticeable loss of catalytic activity. Copyright Taylor & Francis Group, LLC.
- Boroujeni, Kaveh Parvanak
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experimental part
p. 277 - 284
(2011/03/20)
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- Conjugate polymer-supported acid catalysts: An efficient and reusable catalyst for the synthesis of geminal diacetates (acylals) under solvent-free conditions
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A comparative study on the catalytic activity of conducting polyaniline (PANI), polypyrrole (PPY), and poly-(3,4-ethylenedioxythiophene) (PEDOT) salts as solid acid catalysts for the synthesis of 1,1-diacetates (acylals) under solvent-free conditions has been presented. Use of the polypyrrole and poly-(3,4-ethylenedioxythiophene) salts as solid acid catalysts is reported for the first time. Preparation, recovery, and reusability of the catalysts were found to be good. Copyright Taylor & Francis Group, LLC.
- Nabid, Mohammad Reza,Rezaei, Seyed Jamal Tabatabaei,Abedi, Mahvash
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experimental part
p. 191 - 199
(2011/03/18)
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- A simple and fast method for protection of aldehydes as 1,1-diacetates using cerium(IV) sulfate as an efficient and reusable inorganic catalyst
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A simple, green, and very fast method for protection of aryl aldehydes as 1,1-diacetates promoted by cerium(IV) sulfate tetrahydrate, Ce(SO 4)2·4H2O, as a novel inorganic solid acid catalyst at room temperature and under solvent-free conditions is described. The present methodology offers several advantages, such as a simple procedure with an easy workup, very short reaction times, high yields, and the absence of any volatile and hazardous organic solvents. Copyright Taylor & Francis Group, LLC.
- Saburi, Elahe,Davoodnia, Abolghasem,Tavakoli-Hoseini, Niloofar
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experimental part
p. 1063 - 1066
(2012/02/16)
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- P2O5/Al2O3 AS an efficient heterogeneous catalyst for the acetylation of alcohols, phenols, thiols, and amines under solvent-free conditions
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A convenient, rapid, and efficient method for the acetylation of alcohols, phenols, thiols, and amines has been developed by using acetic anhydride in the presence of a catalytic amount of P2O5/Al 2O3 under solvent-free conditions at room temperature. This reaction was studied under different conditions, and several solvents were examined for this conversion. However, in terms of reaction time and yield, it was found that the best result was obtained when the reaction was carried out under solvent-free conditions. Racemization of optically active alcohols and epimerization of sugars were not observed. The use of nontoxic and inexpensive materials, simple and clean workup, short reaction times, and good yields of the products are the advantages of this method.
- Zarei, Amin,Hajipour, Abdol R.,Khazdooz, Leila
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experimental part
p. 1772 - 1785
(2011/06/20)
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- A new and efficient procedure for the production of 1,1-diacetate from corresponding aldehydes promoted by silica chromate (SiO2-O-CrO 2-O-SiO2)
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Chemical Equation Presented A wide range of aromatic aldehydes has been selectively converted to 1,1-diacetates using silica chromate (SiO 2-O-CrO2-O-SiO2) under solvent-free conditions at room temperature in moderate to good yields. This protocol is mild and efficient compared to other reported methods. Copyright Taylor & Francis Group, LLC.
- Bamoniri, Abdolhamid,Ghorbani-Choghamarani, Arash,Mirjalili, Bi Bi Fatemeh
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experimental part
p. 381 - 388
(2011/04/22)
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- Study of reaction of isomeric acetoxytoluenes with ozone in liquid phase in the presence of manganese bromide catalyst
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The kinetics of the ozone reaction with isomeric acetoxytoluenes in acetic anhydride in the presence of sulfuric acid and mixed manganese bromide catalyst was studied. Under these conditions it is possible to stop the oxidation process at the stage of formation of hydroxybenzaldehydes in the form of the respective acetoxybenzylidendiacetates (63-70%). The reaction products contain also acetoxybenzyl acetate (16-18%) and a small amount of acetoxybenzyl bromide (2%). The mechanism of oxidation-reduction catalysis with manganese bromide complex explaining the experimental data was considered. Pleiades Publishing, Ltd., 2010.
- Galstyan,Sedykh
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scheme or table
p. 948 - 952
(2011/01/07)
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- An efficient and chemoselective procedure for acylal synthesis
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A novel heterogeneous efficient procedure has been developed for the chemoselective synthesis of acylals (1,1-diacetates) under solvent-free conditions. A novel catalyst prepared by the sulfuric acid catalyzed copolymerization of p-toluenesulfonic acid and paraformaldehyde displays extremely high activities for the title reactions, affording average yields over 90% within several minutes. A comparative study showed that the novel catalyst has much higher activity than other catalysts used for this purpose. Besides, the novel catalyst displays chemoselectivity for the protection of aldehydes in the presence of ketones. In addition the high acidity (4.0 mmol/g), thermal stability (200 °C) and easy reusability make the novel catalyst one of the best choices for the process.
- Fan, Da-He,Wang, Hui,Mao, Xing-Xing,Shen, Yong-Miao
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experimental part
p. 6493 - 6501
(2010/11/04)
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- Chemoselective synthesis of 1,1-diacetates from aldehydes using anhydrous cobalt(II) bromide under solvent-free conditions
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A mild and efficient method has been developed for the chemoselective preparation of 1,1-diacetates (acylals) from aldehydes catalyzed in the presence of a catalytic amount (0.1mmol) of anhydrous cobalt(II) bromide under solvent-free conditions. The remarkable selectivity under mild and neutral conditions, excellent yields, short reaction time, and easily available and inexpensive catalyst are important features of this method.
- Meshram, Gangadhar A.,Patil, Vishvanath D.
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experimental part
p. 442 - 449
(2010/04/02)
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- Sulphated zirconia as an eco-friendly catalyst in acylal preparation under solvent-free conditions, acylal deprotection assisted by microwaves, and the synthesis of anhydro-dimers of o-hydroxybenzaldehydes
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A solvent-free approach is described for the regioselective synthesis of acylals (1,1-diacetates) in shorter reaction times and higher yields, compared to conventional methodology using solvents. In the protection reaction of the o-hydroxybenzaldehyde the formation of acetyl compounds and anhydro-dimers was observed. The deprotection reaction involves microwave (MW) exposure of diluted reactants in the presence of solid sulphated zirconia (SZ) catalyst that can be easily recovered and reused. The sulphated zirconia was recycled several times without any loss of activity.
- Palacios-Grijalva, Laura Nadxieli,Cruz-Gonzalez, Deysi Y.,Lomas-Romero, Leticia,Gonzalez-Zamora, Eduardo,Ulibarri, Gerardo,Negron-Silva, Guillermo E.
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experimental part
p. 4065 - 4078
(2010/03/01)
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- Oxidation of 2-acetoxytoluene with ozone in acetic anhydride
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Kinetics and mechanism of the reaction of ozone with 2-acetoxytoluene in acetic anhydride in the presence of sulfuric acid were studied. It was shown that the prevailing reaction route under these conditions is ozonolysis (89%), and the selectivity of the oxidation of the substrate by the methyl group is no higher 9%. However, in the presence of manganese(II) sulfate as a catalyst, the selectivity increases to 76%. The major reaction products were 2-acetoxybenzyl acetate (59%) and 2-acetoxybenzylidene diacetate (17%). In the presence of a manganese bromide catalyst, the oxidation depth increases, and the major reaction product is already 2-acetoxybenzylidene (66%), while the yield of 2-acetoxybenzyl acetate is 15%. The mechanism of the redox catalysis is considered, that explains the experimental results.
- Galstyan
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experimental part
p. 1690 - 1694
(2009/02/06)
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- An efficient method for the synthesis of acylals from aldehydes under solvent-free conditions catalyzed by antimony trichloride
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A mild and efficient method has been developed for the preparation of acylals from aldehydes catalyzed by antimony trichloride under solvent-free conditions in very good to excellent yields. The easy availability, low cost, and ease of handling of the catalyst make this procedure especially attractive for large-scale synthesis. Copyright Taylor & Francis Group, LLC.
- Bhattacharya, Asish K.,Mujahid, Mohammad,Natu, Arvind A.
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p. 128 - 134
(2008/03/14)
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- Synthesis of 1,1-diacetates using a new combined catalytic system: Copper p-toluenesulfonate/HOAc
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Copper p-toluenesulfonate acetic acid has been established as an efficient combined catalytic system for chemoselective conversion of aldehydes to diacetates in high yields at ambient temperature in short reaction times. For the catalytic system, the amount of copper p-toluenesulfonate reduced to 0.3 mol%. After the reaction, copper p-toluenesulfonate can be easily recovered and reused for at least 10 runs. Copyright Taylor & Francis Group, LLC.
- Wang, Min,Song, Zhiguo,Gong, Hong,Jiang, Heng
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p. 961 - 966
(2008/09/17)
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- PEG-supported sulfonic acid as an efficient and recyclable catalyst for the synthesis of 1,1-diacetates under solvent-free conditions
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An operationally simple, efficient, and environmentally benign synthesis of 1,1-diacetates in good yields by reaction of different aldehydes with acetic anhydride in the presence of PEG-supported sulfonic acid under solvent-free conditions is described. C
- Wang, Qiu-Ying,Sheng, Shou-Ri,Wei, Mei-Hong,Xie, Zhong-Li,Liu, Xiao-Ling
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p. 1019 - 1026
(2007/10/03)
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- Physicochemical behaviour of copper(II) complexes of chelated diamine ligands: Catalytic role of diaquabis(ethylenediamine)copper(II) perchlorate in acylal formation
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Preparation and properties of a few chelated diamine complexes of copper(II) are reported. The compounds, [Cu(en)2(H2O) 2](ClO4)2 (1), [Cu(tmen)2(H 2O)2](C1O4)2 (2), [Cu 2(en)2Cl4]n (3) and [Cu 2(en)2(SO4)2(H2O) 4].2H2O (4) have been prepared in moderate to excellent yields and characterized by various physicochemical techniques. The structure of [Cu2(en)2Cl4]n (3) has been determined by single crystal X-ray diffraction. Complex 3 crystallizes in monoclinic space group P21/m, with unit cell parameters a = 6.7850 (14) A, b = 5.7600(12)A, c = 8.2240(16)A, β= 93.75(3)°, V = 320.7(1)A3. The structure has been solved by direct method and refined by full-matrix least squares to final R1 = 0.0460, wR2 = 0.1249 and GooF = 1.135 for all 818 reflections. Each copper atom in complex 3 is present in a distorted octahedral environment created by a chelating ethylenediamine ligand and four chlorine atoms. Two adjacent parallel -Cu-Cl-Cu- chains joined by short Cu-Cl bonds give rise to a zigzag ribbon-like polymer. Complex 1 has been studied as a catalyst for the conversion of aromatic aldehydes to acylals under solvent-free conditions at room temperature.
- Sarmah, Purabi,Singha, Sunita,Chakrabarty, Rajesh,Bora, Sanchay J.,Das, Birinchi K.
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p. 1929 - 1937
(2008/03/15)
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- An efficient procedure for the synthesis of 1,1-diacetates from aldehydes with acetic anhydride catalyzed by silica sulfate
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The reaction of aldehyde with acetic anhydride catalyzed by silica sulfate results in 1,1-diacetates in high yields at room temperature.
- Jin, Tong-Shou,Zhao, Ying,Gu, Shu-Qing,Liu, Li-Bin,Li, Tong-Shuang
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p. 1054 - 1056
(2007/10/03)
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- An efficient and practical procedure for preparation of gem-diacetates from aldehydes catalysed by magnesium perchlorate
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A mild and efficient method for the preparation of grem-diacetates from aldehydes with acetic anhydride is described using a catalytic amount of magnesium perchlorate giving excellent yields under solvent-free conditions.
- Yang, Shu-Tao
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p. 199 - 202
(2007/10/03)
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- Acetic acid-assisted copper methanesulfonate catalyst for chemoselective conversion of aldehydes to acylals
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A new catalytic system has been discovered by combining copper methanesulfonate with acetic acid for chemoselective conversion of aldehydes to acylals in high yields at ambient temperature under solvent-free conditions. The efficiency of this system might result from the "double activation" of Bronsted-Lewis acid catalysis on aldehydes. Copyright Taylor & Francis Group, LLC.
- Wang, Min,Gong, Hong,Jiang, Heng,Wang, Zhichang
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p. 1953 - 1960
(2007/10/03)
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- Reinvestigation of the mechanism of gem-diacylation: Chemoselective conversion of aldehydes to various gem-diacylates and their cleavage under acidic and basic conditions
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The mechanism of gem-diacylate formation has been studied extensively using tetrabutylammonium tribromide (TBATB) as the catalyst. The reaction proceeds by a nucleophilic attack of an anhydride on an aldehydic carbonyl group, nucleophilic attack of the hemiacylate intermediate on a second molecule of the anhydride, followed by an intermolecular attack of a second acetate group to regenerate the anhydride. gem-Diacylates of various aliphatic and aromatic aldehydes were obtained directly from the reaction of a variety of aliphatic and aromatic acid anhydrides in the presence of a catalytic quantity of tetrabutylammonium tribromide (TBATB) under solvent-free conditions. A significant electronic effect was observed during its formation as well as deprotection to the corresponding aldehyde. Chemoselective gem-diacylation of the aromatic aldehyde containing an electron-donating group has been achieved in the presence of an aldehyde containing an electron-withdrawing group. Deprotection of the gem-diacylate to the parent carbonyl compound can be accomplished in methanol in presence of the same catalyst. Here again, chemoselective deprotection of the gem-diacylate of a substrate containing an electron-donating group has been achieved in the presence of a substrate containing an electron-withdrawing group. Both the acid and base stability order of the various gem-diacylates examined follow a similar order. The stability order determined from the present study is: gem-dibenzoate > gem-dipivalate > gem-diisobutyrate > gem-diacetate > gem-dipropionate. All the gem-diacylals are more stable under basic conditions than acidic condition. No correlation was found between the stability order and the pKa's of the corresponding acids; rather, the stability order is directly related to the steric crowding around the carbonyl carbon. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005.
- Kavala, Veerababurao,Patel, Bhisma K.
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p. 441 - 451
(2007/10/03)
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- Synthesis of 1,1-diacetates from aromatic aldehydes using cerium(IV) sulfate tetrahydrate as catalyst under solvent-free conditions
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Aromatic aldehydes can be converted into the corresponding 1,1-diacetates rapidly in the presence of catalytic amounts of Ce(SO4) 2·4H2O at room temperature in excellent yield under solvent-free conditions. The catalyst can easily be recovered and reused at least 4 times.
- Zhang, Min,Li, Yi-Qun
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p. 171 - 172
(2007/10/03)
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- Silica sulfuric acid as an efficient heterogeneous catalyst for the synthesis of 1,1-diacetates under solvent-free conditions
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An efficient method for the preparation of acylals from different aldehydes in the presence of silica sulfuric acid and acetic anhydride under solvent-free conditions is reported. Georg Thieme Verlag Stuttgart.
- Hajipour, Abdol R.,Zarei, Amin,Khazdooz, Leila,Mirjalili, Bi Bi F.,Sheikhan, Nafise,Zahmatkesh, Saeed,Ruoho, Arnold E.
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p. 3644 - 3648
(2007/10/03)
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- An efficient and practical procedure for synthesis of 1,1-diacetates from aldehydes catalyzed by zirconium sulfate tetrahydrate-silica gel
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A facile and efficient procedure for synthesis of 1,1-diacetates from aldehydes with acetic anhydride was described using zirconium sulfate tetrahydrate-silica gel as catalyst in excellent yields under mild reaction conditions.
- Jin, Tongshou,Feng, Guoliang,Yang, Mina,Li, Tongshuang
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p. 1645 - 1651
(2007/10/03)
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- An efficient conversion of aldehydes to their corresponding acylals with P2O5/SiO2 under mild condition
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A combination of P2O5 and SiO2 was used for an efficient conversion of aldehydes to their corresponding acylals with excellent yields at room temperature under mild conditions.
- Mirjalili, Bibi Fatemeh,Zolfigol, Mohammad Ali,Bamoniri, Abdolhamid
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- Solvent-free catalytic preparation of 1,1-diacetates from aldehydes using a Wells-Dawson acid (H6P2W18O62·24H 2O)
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Aromatic and aliphatic aldehydes are transformed in 1,1-diacetates (acylals) in mild conditions, by a treatment with acetic anhydride and a Wells-Dawson acid (H6P2W18O62·24H 2O). gem-Diacetylation proceeds in Ac2O with a little as 1% mol Wells-Dawson acid at room temperature and under solventless conditions, obtaining very good to excellent yields (88-98%) of 1,1-diacetates (19 examples). Neither 4-dimethylaminobenzaldehyde nor ketones react under the same conditions.
- Romanelli, Gustavo P.,Thomas, Horacio J.,Baronetti, Graciela T.,Autino, Juan C.
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p. 1301 - 1303
(2007/10/03)
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- An efficient and convenient procedure for the synthesis of 1,1-diacetates of aldehydes catalysed by anhydrous ferrous sulfate
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1,1-Diacetates of aldehydes have been selectively prepared in the presence of ketones in excellent yields under the catalysis of anhydrous ferrous sulfate at room temperature.
- Jin, Tong-Shou,Du, Gui-Ying,Li, Tong-Shuang
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p. 939 - 940
(2007/10/03)
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- A rapid preparation of acylals of aldehydes catalysed by Fe3+- montmorillonite
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Aldehydes can be converted to acylals by treatment with acetic anhydride in the presence of Fe3+-montmorillonite in excellent yield at room temperature.
- Li, Tong-Shuang,Zhang, Zhan-Hui,Gao, Yong-Jian
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p. 4665 - 4671
(2007/10/03)
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- An efficient and convenient procedure for preparation of 1,1-diacetates from aldehydes catalysed by expansive graphite
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An easy preparation of 1,1-diacetates from aldehydes has been carried out in excellent yield under catalysis of expansive graphite at room temperature.
- Jin, Tong-Shou,Du, Gui-Ying,Zhang, Zhan-Hui,Li, Tong-Shuang
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p. 2261 - 2266
(2007/10/03)
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- Montmorillonite Clay Catalysis. Part 4.11 An Efficient and Convenient Procedure for Preparation of 1,1-Diacetates from Aldehydes
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An easy preparation of 1,1-diacetates from aldehydes with montmorillonite clays as catalysts has been carried out in excellent yield.
- Zhang, Zhan-Hui,Li, Tong-Shuang,Fu, Cheng-Guang
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p. 174 - 175
(2007/10/03)
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- Cobalt(II)-Catalyzed Reaction of Aldehydes with Acetic Anhydride under an Oxygen Atmosphere: Scope and Mechanism
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The reaction of aldehydes with acetic anhydride in the presence of catalytic cobalt(II) chloride under an oxygen atmosphere at ambient temperature is dependent upon the reaction medium.Aliphatic aldehydes react in acetonitrile to give 1,2-diones whereas the aromatic aldehydes are acylated to yield the corresponding acylals.On the other hand, carboxylic acids are obtained from aliphatic and aromatic aldehydes by conducting the reaction in dichloroethane or benzene.Cobalt(II) chloride in acetonitrile catalyzes the conversion of aliphatic aldehydes to the correspondinganhydrides in the absence of acetic anhydride whereas aromatic aldehydes remain largely unaffected under these conditions.A preliminary mechanistic study in three different solvents (i.e. acetonitrile, dichloroethane, and DMF) has revealed that in acetonitrile and in the presence of acetic anhydride, aliphatic aldehydes behave differently than aromatic aldehydes.Some trapping experiments using methyl acrylate and stilbene have been conducted to demonstrate the occurence of an acyl cobalt and peroxyacyl cobalt intermediate during these reactions.
- Bhatia, Beena,Punniyamurthy, T.,Iqbal, Javed
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p. 5518 - 5523
(2007/10/02)
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