- The studies on chemoselective promiscuous activity of hydrolases on acylals transformations
-
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
-
-
- SiO2@FeSO4 nano composite as nanocatalyst for the green synthesis 1,1-diacetates from aldehydes under solvent-free conditions
-
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
-
p. 2780 - 2783
(2016/07/12)
-
- Tungstosulfonic acid as an efficient solid acid catalyst for acylal synthesis for the protection of the aldehydic carbonyl group
-
Tungstosulfonic acid (TSA) has been found to be an efficient solid acid catalyst for the protection of aldehydic carbonyl groups by geminal diacetate (acylal) formation following the nucleophilic addition of acetic anhydride under neat conditions as well as in a solvent. The TSA catalyst is fully characterized by infrared spectroscopy, wide-angle X-ray scattering analysis, and scanning electron microscopy with energy dispersive X-ray spectroscopy. The deprotection of acylals to corresponding aldehydes has also been investigated under the similar conditions. The catalyst can be reused seven times without a significant loss of activity. In addition, no chromatographic separations are needed to obtain the desired products. This method is a green approach for the chemoselective protection of aldehydes in the presence of ketones.
- Kalla, Reddi Mohan Naidu,Kim, Mi Ri,Kim, Yu Na,Kim, Il
-
supporting information
p. 687 - 693
(2016/01/12)
-
- Formation of benzylidenes-diacetates catalyzed by activated zeolite "LZY-562" and clay (K10/ZnCl2): An unexpected functional selectivity
-
Activated zeolites LZY-562 and clay montmorillonite K10 at room temperature without solvent catalyzes the synthesis of benzylidenesdiacetates from carbonyl compounds. A chemoselectivity was observed between aldehydes and ketones, between the different aldehydes and ketones as well.
- Dokari,Hammadi,Benferrah,Rachedi
-
p. 1973 - 1976
(2015/12/01)
-
- Poly(4-vinylpyridinium) perchlorate as an efficient solid acid catalyst for the chemoselective preparation of 1,1-diacetates from aldehydes under solvent-free conditions
-
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
-
p. 329 - 334
(2014/04/03)
-
- An efficient method for synthesis of acylals from aldehydes using multi-walled carbon nanotubes functionalized with phosphonic acid (MWCNTs-C-PO3H2)
-
MWCNTs-C-PO3H2 has been used as an efficient, heterogeneous and reusable nanocatalyst for synthesis of acylals from aldehydes under solvent-free conditions at room temperature. A wide range of aldehydes was studied and corresponding products were obtained in good to excellent yields in short reaction times. Nanocatalyst can be easily recovered by centrifuge and reused for subsequent reactions for at least five times without deterioration in catalytic activity. The major advantages of the present method are high yields, short reaction time, recyclable catalyst and solvent-free reaction conditions at room temperature.
- Dehghani, Farzaneh,Sardarian, Ali Reza,Doroodmand, Mohammad Mehdi
-
p. 1630 - 1634
(2015/01/09)
-
- Catalysis of reaction between ozone and 4-hydroxytoluene in acetic anhydride
-
Kinetics and products of 4-hydroxytoluene oxidation with ozone-air mixture in the presence of transition metal acetates as catalysts have been studied. Main steps of the catalytic series have been considered, and a mechanism of redox catalysis has been proposed which conforms to the experimental data and enables control over the direction, depth, and selectivity of the oxidation. Only manganese(II) acetate has been found to exhibit high catalytic activity in the presence of catalytic amounts of mineral acids. Manganese(II) acetate largely suppresses electrophilic reaction of ozone with the aromatic ring, so that the main reaction direction is oxidation of the methyl group with formation of 4-acetoxybenzyl acetate as the major product (62.6%) and 4-acetoxybenzylidene diacetate as a minor one (10.2%).
- Galstyan, A. G.,Sedykh, A. A.,Galstyan, G. A.
-
p. 1510 - 1514
(2014/12/10)
-
- P4VP-H2SO4-catalyzed chemoselective protection of aldehydes to acylal along with deprotection reactions
-
Poly(4-vinylpyridine)-supported sulfuric acid is an excellent reusable heterogeneous catalyst for the chemoselective synthesis of 1,1- diacetates(acylal) from aldehydes in dichloromethane at room temperature within a few minutes. The protection of salicyaldehyde generated an anhydro-dimer as single product under similar reaction conditions. The catalyst is equally applicable for the deprotection of acylal in acetonitrile. The catalyst was prepared by the wet impregnation technique.
- Dutta, Papia,Sarma, Parishmita,Borah, Ruli
-
p. 1378 - 1386
(2013/05/09)
-
- 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
-
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
-
-
- PEG-SO3H as an efficient and reusable catalyst for chemoselective synthesis of 1,1-diacetates
-
An efficient and convenient procedure of the synthesis of 1,1-diacetates from aromatic aldehydes and acetic anhydride under mild and solvent-free conditions at room temperature, in the presence of PEG-SO3H is reported. PEG-SO3H acts as a catalyst and can be recovered and reused eight times without apparent loss of its catalytic activity.
- Zong, Ying-Xiao,Wang, Jun-Ke,Niu, Yu-Ying,Li, Zheng-Liang,Song, Zheng-En,Quan, Zheng-Jun,Wang, Xi-Cun,Yue, Guo-Ren,Pan, Yi
-
p. 140 - 142
(2013/06/26)
-
- Solvent-free catalytic preparation of 1,1-diacetates using a silica-supported functional ionic liquid as catalyst
-
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
-
p. 247 - 249
(2013/07/27)
-
- Polystyrene-supported TiCl4 as a novel, efficient and reusable polymeric Lewis acid catalyst for the chemoselective synthesis and deprotection of 1,1-diacetates under eco-friendly conditions
-
Copolymer beads of styrene and divinylbenzene (5-7%) were synthesized and combined with titanium tetrachloride in CS2 to form a stable complex. The PS/TiCl4 complex was used as a mild and efficient polymer-supported Lewis acid catalyst for the preparation of 1,1-diacetates from various types of aldehydes under heterogeneous conditions at room temperature. Deprotection of the resulting 1,1-diacetates has also been achieved using the same catalyst in methanol. This new protocol has the advantages of easy availability, stability, reusability of the eco-friendly catalyst, high to excellent yields, chemoselectivity, simple experimental and work-up procedure. Moreover, this polymeric catalyst could be recovered easily and reused several times without significant loss in activity.
- Rahmatpour, Ali,Mohammadian, Sara
-
p. 912 - 919
(2013/10/22)
-
- A rapid, convenient and chemoselective synthesis of acylals from aldehydes catalyzed by reusable nano-ordered MCM-41-SO3H
-
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
-
p. 1072 - 1076
(2013/02/22)
-
- Ultrasound-assisted synthesis of acylals catalyzed by stannum (IV) phosphomolybdate under solvent-free condition
-
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
-
experimental part
p. 299 - 301
(2012/07/17)
-
- 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
-
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
-
experimental part
p. 61 - 69
(2012/04/17)
-
- A simple and fast method for protection of aldehydes as 1,1-diacetates using cerium(IV) sulfate as an efficient and reusable inorganic catalyst
-
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
-
experimental part
p. 1063 - 1066
(2012/02/16)
-
- P2O5/Al2O3 AS an efficient heterogeneous catalyst for the acetylation of alcohols, phenols, thiols, and amines under solvent-free conditions
-
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
-
experimental part
p. 1772 - 1785
(2011/06/20)
-
- Preparation of silica-bonded propyl-diethylene-triamine-N-sulfamic acid as a recyclable catalyst for chemoselective synthesis of 1,1-diacetates
-
A simple and efficient procedure for the preparation of silica-bonded propyl-diethylene-triamine-N-sulfamic acid (SPDTSA) by reaction of 3-diethylenetriamine-propylsilica (DTPS) and chlorosulfonic acid in chloroform is described. Silica-bonded propyl-diethylene-triamine-N-sulfamic acid is employed as a recyclable catalyst for the synthesis of 1,1-diacetates from aromatic aldehydes and acetic anhydride under mild and solvent-free conditions at room temperature. Catalyst could be recycled for several times without any additional treatment.
- Nouri Sefat, Maryam,Deris, Abdolah,Niknam, Khodabakhsh
-
experimental part
p. 2361 - 2367
(2012/02/03)
-
- An efficient and chemoselective procedure for acylal synthesis
-
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
-
experimental part
p. 6493 - 6501
(2010/11/04)
-
- Chemoselective synthesis of 1,1-diacetates from aldehydes using anhydrous cobalt(II) bromide under solvent-free conditions
-
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.
-
experimental part
p. 442 - 449
(2010/04/02)
-
- Silica phosphoric acid: An efficient and recyclable catalyst for the solvent-free synthesis of acylals and their deprotection in MeOH
-
Silica phosphoric acid was used as an efficient, mild, and recyclable solid catalyst for the synthesis of acylals from various structurally diverse aldehydes and acetic anhydride under solvent-free conditions. The acylation of aldehydes was highly chemoselective, and no ketone was acylated, which provided a method for the synthesis of acylals from aldehydes in the presence of ketones. Silica phosphoric acid-catalyzed deprotection of acylals to the corresponding aldehydes in MeOH has also been developed with excellent yield. The deprotection of the acylals of aromatic aldehydes took priority over those of aliphatic aldehydes. Copyright Taylor & Francis Group, LLC.
- Zhang, Fuyi,Liu, Hong,Zhang, Qing-Ju,Zhao, Yu-Fen,Yang, Feng-Ling
-
experimental part
p. 3240 - 3250
(2010/12/24)
-
- Study of reaction of isomeric acetoxytoluenes with ozone in liquid phase in the presence of manganese bromide catalyst
-
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
-
scheme or table
p. 948 - 952
(2011/01/07)
-
- Liquid-phase reactions of isomeric methylphenols with ozone
-
Ozonation of isomeric methylphenols in acetic anhydride was studied. Here, acetic anhydride acts simultaneously as solvent and acylating agent. In the presence of a mineral acid methylphenols were converted into methylphenyl acetates during preparation of solutions for ozonation. The major products in the oxidation of isomeric methylphenyl acetates with ozone were aliphatic peroxides (80-90%); oxidation of the methyl group gave rise to the corresponding acetoxybenzyl acetates (7-14%) and acetoxybenzylidene diacetates (3-6%). A probable scheme for the liquid-phase oxidation of methylphenyl acetates with ozone in acetic anhydride was proposed.
- Galstyan
-
scheme or table
p. 15 - 19
(2010/05/01)
-
- Silica-bonded S-sulfonic acid as a recyclable catalyst for chemoselective synthesis of 1,1-diacetates
-
A simple and efficient procedure for the preparation of silica-bonded S-sulfonic acid (SBSSA) by reaction of 3-mercaptopropylsilica (MPS) and chlorosulfonic acid in chloroform is described. This solid acid is employed as a recyclable catalyst for the synthesis of 1,1-diacetates from aromatic aldehydes and acetic anhydride under mild and solvent-free conditions at room temperature.
- Niknam, Khodabakhsh,Saberi, Dariush,Sefat, Maryam Nouri
-
scheme or table
p. 4058 - 4062
(2009/10/11)
-
- 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
-
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.
-
scheme or table
p. 4065 - 4078
(2010/03/01)
-
- An efficient method for the synthesis of acylals from aldehydes under solvent-free conditions catalyzed by antimony trichloride
-
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.
-
p. 128 - 134
(2008/03/14)
-
- Synthesis of 1,1-diacetates using a new combined catalytic system: Copper p-toluenesulfonate/HOAc
-
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
-
p. 961 - 966
(2008/09/17)
-
- P2O5/Al2O3 as an efficient heterogeneous catalyst for chemoselective synthesis of 1,1-diacetates under solvent-free conditions
-
An efficient and chemoselective method for the preparation of acylals from different aldehydes using P2O5/Al2O3 and acetic anhydride under solvent-free conditions.
- Hajipour, Abdol R.,Zarei, Amin,Ruoho, Arnold E.
-
p. 2881 - 2884
(2007/10/03)
-
- Chemistry of acylals, part IV: BF3-catalyzed formation of substituted α,α′-bis(arylmethylidene)cycloalkanones from acylals and 1-cycloalkenyl trimethylsilyl ethers
-
When mixtures of an aromatic aldehyde acylal and a I-cycloalkenyl trimethylsilyl ether in dichloromethane were treated with boron trifluoride at room temperature, the corresponding α,α′-bis(arylmethylidene) cycloalkanones were formed. The yield was sensitive to both the acetal/ether ratio and the structure of the acylal. The best results, up to 97% yield, were obtained when acylals containing a diacetoxy moiety were reacted with 1-cyclohexenyl trimethylsilyl ether with an acetal-to-ether ratio of 2:1. Georg Thieme Verlag Stuttgart.
- Sydnes, Leiv K.,Pedersen, Gry S.,Holmelid, Bjarte,Sandberg, Marcel
-
p. 3692 - 3696
(2008/09/19)
-
- An efficient procedure for the synthesis of 1,1-diacetates from aldehydes with acetic anhydride catalyzed by silica sulfate
-
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
-
p. 1054 - 1056
(2007/10/03)
-
- Acetic acid-assisted copper methanesulfonate catalyst for chemoselective conversion of aldehydes to acylals
-
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
-
p. 1953 - 1960
(2007/10/03)
-
- Oxidation of p-cresol with ozone in acetic anhydride
-
Preparation of aromatic alcohols and aldehydes by oxidation of p-cresol with ozone in acetic anhydride in the presence of sulfuric acid, manganese acetate, and potassium bromide was studied. The optimal oxidation conditions were determined. Pleiades Publishing, Inc., 2006.
- Sedykh,Galstyan
-
p. 123 - 126
(2008/02/04)
-
- Protection of aldehydes as 1,1-diacetates and deprotection of 1,1-diacetates to aldehydes
-
Protection of aldehydes as 1,1-diacetates using Ac2O/acidic alumina and deprotection of 1,1-diacetates to aldehydes using acidic alumina has been reported by microwave irradiation. Selective protection in the case of 4-hydroxybenzaldehyde, 4-hydroxy-3-methoxybenzaldehyde and deprotection in the case of 4-acetoxybenzaldehyde diacetate are described.
- Nanda, Puja,Paul, Satya,Gupta, Rajive
-
p. 1547 - 1550
(2007/10/03)
-
- Reinvestigation of the mechanism of gem-diacylation: Chemoselective conversion of aldehydes to various gem-diacylates and their cleavage under acidic and basic conditions
-
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.
-
p. 441 - 451
(2007/10/03)
-
- Synthesis of 1,1-diacetates from aromatic aldehydes using cerium(IV) sulfate tetrahydrate as catalyst under solvent-free conditions
-
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
-
p. 171 - 172
(2007/10/03)
-
- Lithium chloride-assisted chemoselective conversion of aldehydes into geminal diacetates under solvent-free conditions
-
A mixture of lithium chloride and acetic anhydride was used for converting aldehydes into geminal diacetates under solvent-free conditions in high yields. Copyright Taylor & Francis, Inc.
- Bosco, J.W. John,Purkayastha,Raju, B. Rama,Saikia, Anil K.
-
p. 1301 - 1305
(2007/10/03)
-
- Indium tribromide as a highly efficient and versatile catalyst for chemoselective synthesis of acylals from aldehydes under solvent-free conditions
-
A mild and efficient method has been developed for the chemoselective preparation of acylals from aldehydes in the presence of catalytic amounts (0.01-1.0 mol%) of InBr3 under solvent-free conditions in very good to excellent yields.
- Yin, Liang,Zhang, Zhan-Hui,Wang, Yong-Mei,Pang, Mei-Li
-
p. 1727 - 1730
(2007/10/03)
-
- Phosphorus pentoxide-montmorillonite K-10 as catalyst for the preparation of 1,1-diacetates under solvent-free conditions
-
A facile and efficient method for the preparation of 1,1-diacetates of aldehydes is improved. P2O5/montmorillonite K10 catalyzed 1,1-diacetates formation from aldehydes in dry media. Both aromatic and aliphatic aldehydes gave high yields (70-95%) of the corresponding 1,1-diacetates. Advantages of this method are the use of an inexpensive and selective catalyst, with high yields in simple operation and short reaction time under solvent-free conditions.
- Eshghi, Hossein,Gordi, Zinat
-
p. 1341 - 1346
(2007/10/03)
-
- An efficient conversion of aldehydes to their corresponding acylals with P2O5/SiO2 under mild condition
-
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
-
-
- Bismuth compounds in organic synthesis. Bismuth nitrate catalyzed chemoselective synthesis of acylals from aromatic aldehydes
-
Aromatic aldehydes are smoothly converted into the corresponding acylals in good yields in the presence of 3-10mol% Bi(NO3) 3·5H2O. Ketones are not affected under the reaction conditions. The relatively non-toxic nature of the catalyst, its ease of handling, easy availability and low cost make this procedure especially attractive for large-scale synthesis.
- Aggen, David H.,Arnold, Joshua N.,Hayes, Patrick D.,Smoter, Nathaniel J.,Mohan, Ram S.
-
p. 3675 - 3679
(2007/10/03)
-
- Fluoroboric acid adsorbed on silica gel as a new and efficient catalyst for acylation of phenols, thiols, alcohols, and amines
-
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
-
p. 3521 - 3525
(2007/10/03)
-
- An efficient method for the chemoselective synthesis of acylals from aromatic aldehydes using bismuth triflate
-
Aromatic aldehydes are smoothly converted into the corresponding acylals in good yields in the presence of 0.10 mol% Bi(OTf)3·xH2O. Ketones are not affected under the reaction conditions. The highly catalytic nature of bismuth triflate and the fact that it is relatively non-toxic, easy to handle and insensitive to small amounts of air and moisture makes this procedure especially attractive for large-scale synthesis.
- Carrigan, Marc D.,Eash, Kyle J.,Oswald, Matthew C.,Mohan, Ram S.
-
p. 8133 - 8135
(2007/10/03)
-
- Conversion of aldehydes into geminal dicarboxylates (acylals) catalyzed by lithium tetrafluoroborate
-
A variety of aldehydes react with acid anhydrides in the presence of a catalytic amount of lithium tetrafluoroborate to afford the corresponding geminal dicarboxylates (acylals) in good to excellent yields.
- Sumida,Nishioka,Sato
-
p. 1921 - 1922
(2015/11/05)
-
- Cobalt(II)-Catalyzed Reaction of Aldehydes with Acetic Anhydride under an Oxygen Atmosphere: Scope and Mechanism
-
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
-
p. 5518 - 5523
(2007/10/02)
-