- Synthesis and cytotoxic properties of some cyclic acetals of diols and their dichlorocyclopropyl derivatives
-
Cyclic acetals of ethylene glycol, cis-but-2-ene-1,4-diol and their dichlorocyclopropyl derivatives were synthesized. Compounds simultaneously containing the gem-dichlorocyclopropane and 1,3-dioxacycloalkane cycles are shown to exhibit cytotoxic activity against the HEK293, SH-SY5Y, HepG2, MCF-7, A549, and Jurkat cell lines. The obtained results open up prospects for further studies of antitumor activity of 2-(2,2-dichlorocyclopropyl)-2-ethyl-1,3-dioxolane.
- Raskil’dina,Kuzmina, U. Sh.,Dzhumaev, Sh. Sh.,Borisova, Yu. G.,Ishmetova,Vakhitova, Yu. V.,Zlotskii
-
p. 475 - 478
(2021/04/09)
-
- Inhibition by Water during Heterogeneous Br?nsted Acid Catalysis by Three-Dimensional Crystalline Organic Salts
-
A new self-assembled and self-healing class of metal free, recyclable, heterogeneous Br?nsted acid catalysts has been developed by the protonation of aniline derivatives (tetrakis(4-aminophenyl)methane, leuco-crystal violet, benzidine, and p-phenylenediamine) with aromatic sulfonic acids (tetrakis(phenyl-4-sulfonic acid)methane, and 2,6-naphthalenedisulfonic acid). As a result, five three-dimensional crystalline organic salts (F-1a, F-1b, F-1c, F-2, and F-3) were obtained, linked by hydrogen bonds and additionally stabilized by the opposite charges of the components. Frameworks F-2 and F-3 were prepared for the first time and characterized by elemental analysis, X-ray structural analysis (for F-2), thermogravimetry, SEM, and FTIR spectroscopy. The catalytic activities of crystalline organic salts F-1-3 have been explored in industrially important epoxide ring-opening and acetal formation reactions. The presence of encapsulated water inside frameworks F-1a and F-2 had an inhibitory effect on the performance of the catalysts. X-ray diffraction analysis of hydrated and dehydrated samples of F-1a and F-2 indicated that water of crystallization served as a cross-linking agent, diminishing the substrate induced "breathing"affinities of the frameworks.
- Belokon, Yuri N.,Gak, Alexander,Khakina, Ekaterina,Khrustalev, Victor N.,Korlyukov, Alexander A.,Kuznetsova, Svetlana,Li, Han,Lobanov, Nikolai,Nelyubina, Yulia,North, Michael,Peregudov, Alexander S.,Riazanov, Vladimir,Zhereb, Vladimir
-
p. 6364 - 6372
(2021/10/20)
-
- Photoredox Oxo-C(sp3)-H Bond Functionalization via in Situ Cu(I)-Acetylide Catalysis
-
A unified strategy for the synthesis of 2-vinyl heterocycles is reported. With visible light irradiation, simple and cheap CuCl is able to functionalize a terminal alkyne, giving Cu(I)-acetylide in situ. Unlike the case of noble metals or organic dye photocatalysts, this critical Cu(I)-acetylide not only activates the C-H bond of terminal alkynes but also serves as a photocatalyst to achieve varieties of 2-vinyl heterocycles in good to excellent yields, even for large scale and late-stage functionalization of natural product.
- Song, Zi-Qi,Liu, Zan,Gan, Qi-Chao,Lei, Tao,Tung, Chen-Ho,Wu, Li-Zhu
-
supporting information
p. 832 - 836
(2020/01/31)
-
- Acid properties of organosiliceous hybrid materials based on pendant (fluoro)aryl-sulfonic groups through a spectroscopic study with probe molecules
-
Two different heterogeneous catalysts carrying aryl-sulfonic moieties, in which the aromatic ring was either fluorinated or not, were successfully synthesized. The multi-step synthetic approaches implemented involved the synthesis of the silyl-derivative, template-free one-pot co-condensation (at low temperature and neutral pH) and tethering reaction. A multi-technique approach was implemented to characterize the hybrid organic-inorganic catalysts involving TGA, N2 physisorption analysis, FTIR spectroscopy, and ss MAS NMR (1H, 13C, 29Si) spectroscopy. Specifically, the acidity of the organosiliceous hybrid materials was studied through the adsorption of probe molecules (i.e. CO at 77 K and NH3 and TMPO at room temperature) and a combination of FTIR and ss MAS NMR spectroscopy. The catalytic activity of the two hybrids was tested in the acetal formation reaction between benzaldehyde and ethylene glycol. Preliminary results indicated superior performances for the fluoro-aryl-sulfonic acid, compared to the non-fluorinated sample. The findings hereby reported open new avenues for the design of heterogeneous sulfonic acids with superior reactivity in acid-catalyzed reactions. Moreover, through the implementation of spectroscopic studies, using probe molecules, it was possible to investigate in detail the acidic properties of hybrid organosiliceous materials.
- Erigoni, Andrea,Paul, Geo,Meazza, Marta,Hernández-Soto, María Consuelo,Miletto, Ivana,Rios, Ramon,Segarra, Candela,Marchese, Leonardo,Raja, Robert,Rey, Fernando,Gianotti, Enrica,Díaz, Urbano
-
p. 6308 - 6317
(2019/11/20)
-
- NiCl2-catalyzed radical cross decarboxylative coupling between arylpropiolic acids and cyclic ethers
-
A direct alkenylation of cyclic ethers via radical cross decarboxylative coupling process catalyzed by NiCl2 and using DTBP as radical initiator and oxidant was developed. A variety of arylpropiolic acids and cyclic ethers were transformed into the corresponding 2-arylvinyl cyclic ethers in moderate to excellent yields. Mechanistic experiments were conducted to determine the nature of the reaction intermediates, and a plausible reaction mechanism involving NiCl2-promoted radical process was proposed.
- Wan, Zi-juan,Wang, Jin-yuan,Luo, Jun
-
supporting information
p. 613 - 616
(2019/01/29)
-
- Hierarchical porous organic polymer as an efficient metal-free catalyst for acetalization of carbonyl compounds with alcohols
-
An efficient melamine-porous organic polymer (M-POP) as N-functionalized organic polymer catalyst was synthesized with melamine and terephthalaldehyde by a facile microwave-assisted method. The synthesized M-POP exhibited a high specific surface area with hierarchical pore structure of both mesoporosity and microporosity. The rich N-moieties namely, C[dbnd]N and N–H from the melamine precursor were found to show hydrogen-bonding ability with various organic molecules such as carbonyl compounds. This was illustrated in the acetalization of aldehydes and ketones with methanol or ethylene glycol under mild conditions as a metal-free H-bonding catalyst with high product selectivity. The superior catalytic performance of M-POP was attributed to the availability of a large number of H-bonding sites both as H-donor and H-acceptor between the reactants and the catalyst.
- Kim, Joong-Jo,Lim, Cheang-Rae,Reddy, Benjaram M.,Park, Sang-Eon
-
-
- Synthesis of dioxolanes and oxazolidines by silica gel catalysis
-
Abstract: Ethylene glycol condensed with carbonyl compounds in the presence of silica gel or alumina, without solvent and under pressure, affords 1,3-dioxolanes. 2-Amino-2-methylpropanol also condensed with carbonyl compounds in the presence of silica gel or an acid-activated clay, without solvent and under pressure, produces oxazolidines. To explain these results, we propose that the glycol and the aminopropanol react with Br?nsted (H+) and Lewis acid sites (Si and Al) located on the surface of the catalysts, leading to the products via various ionic intermediates.
- Rohand, Taoufik,Savary, Jér?me,Markó, István E.
-
p. 1429 - 1436
(2018/06/25)
-
- Peroxide-Free Co(OAc)2-Catalyzed Radical Addition of sp3 C-H Bonds to Alkynes
-
Cobalt-catalyzed radical addition of C-H bonds adjacent to an oxygen atom towards alkynes is described. The reaction proceeded at 60 °C without using additional radical initiators, and leads to 2-vinyl ether derivatives in good yields.
- Zhang, Min,Zhao, Yun,Chen, Wanzhi
-
p. 1342 - 1348
(2017/03/11)
-
- Dimethylzinc-Initiated Radical Coupling of β-Bromostyrenes with Ethers and Amines
-
A new coupling reaction has been developed in which β-bromostyrenes react with ethers and tertiary amines to introduce the styryl group in the α-position. The transformation is mediated by Me2Zn/O2 with 10 % MnCl2 and is believed to proceed by a radical addition-elimination mechanism. The ether and the amine are employed as solvent and the coupling takes place through the most stable α radical for unsymmetrical substrates. The products are obtained in moderate to good yields as the pure E isomers. The coupling can be achieved with a range of smaller cyclic and acyclic ethers/amines as well as various substituted β-bromostyrenes.
- Solvhoj, Amanda,Ahlburg, Andreas,Madsen, Robert
-
p. 16272 - 16279
(2015/11/03)
-
- Highly efficient acetalization of carbonyl compounds catalyzed by anilin-aldehyde resin salts
-
A mild procedures for the syntheses of ethylene acetals and dimethyl acetals from the corresponding aldehydes and ketones catalyzed by 1mol% of anilinealdehyde resin salts are described. This method is also useful for the synthesis of dimethyl acetals of diaryl ketones.
- Tanemura, Kiyoshi,Suzuki, Tsuneo
-
supporting information
p. 797 - 799
(2015/06/22)
-
- Homologative trifluoromethylation of acetals
-
Trifluoroethyl α-insertion of acetals has been developed. Aromatic, heteroaromatic, and alkenyl acetals react with in situ generated (trifluoromethyl)diazomethane in the presence of antimony(V) chloride to furnish α-trifluoromethyl acetals. A stereoselective version of this transformation exploiting the acetal as a chiral auxiliary is also presented. Georg Thieme Verlag Stuttgart · New York.
- Hamilton, James Y.,Morandi, Bill,Carreira, Erick M.
-
p. 1857 - 1862
(2013/07/26)
-
- C-H activation in S-alkenyl sulfoximines: An endo 1,5-hydrogen migration
-
Intramolecular redox reaction: Heating N-alkyl, N-allyl-, and N-benzyl-substituted S-alkenyl sulfoximines under appropriate conditions results in the formation of NH-S-alkyl sulfoximines. The intramolecular redox reaction involves a hydride transfer that occurs by a 6-endo-trig process. The intermediates in the reaction can also give access to four- and six-membered heterocyclic rings and a new class of chiral dienes. Copyright
- Gao, Xuefeng,Gaddam, Vikram,Altenhofer, Erich,Tata, Rama Rao,Cai, Zhengxin,Yongpruksa, Nattawut,Garimallaprabhakaran, Aswin K.,Harmata, Michael
-
p. 7016 - 7019
(2012/10/07)
-
- Bis(perfluorooctanesulfonyl)imide supported on fluorous silica gel: Application to protection of carbonyls
-
The immobilization of bis(perfluorooctanesulfonyl)imide (HNPf2) on fluorous silica gel (FSG) and its utilization in protection of carbonyls have been investigated. This system is reasonably general and can be applied to converting several carbonyls to the corresponding acetals and ketals in good to excellent yields. There is no need for the use of anhydrous solvents or inert atmosphere. Recycling studies have shown that the FSG-supported HNPf2 catalyst can be readily recovered and reused several times without significant loss of activity.
- Hong, Mei,Xiao, Guomin
-
experimental part
p. 121 - 126
(2012/08/28)
-
- Simple and efficient water soluble thioligands for rhodium and iridium catalyzed biphasic hydrogenation
-
The activity of catalytic systems derived from the interaction between Rh(CO)2acac and [Ir(COD)Cl]2, respectively, with the water soluble thioligands (L)-Cysteine (1) and (S)-Captopril (2), was tested in the aqueous biphasic hydrogenation of some representative α,β-unsaturated compounds as 2-cyclohexen-1-one (I), trans-cinnamaldehyde (V) and [3-(1,3-benzodioxol-5-yl)-2-methylpropenal] (X), precursor of the fragrance Helional (XI). The precatalyst Rh/Cap was able to hydrogenate cyclohexenone even at low pressure at 60 °C in a neutral medium while Rh/Cy required either higher pressure and temperature or an alkaline medium. The iridium based catalysts, Ir/Cy and Ir/Cap, showed an analogous trend though their activities were lower than those of the related rhodium catalysts. All the catalysts were easily recycled without significant loss of activity. The rhodium catalysts were also used in the hydrogenation of the above aldehydes V and X and their activity was strongly enhanced when ethylene glycol was used as organic solvent or co-solvent.
- Di Dio, Sabrina,Marchetti, Mauro,Paganelli, Stefano,Piccolo, Oreste
-
scheme or table
p. 205 - 210
(2012/02/02)
-
- Acetalization of carbonyl compounds catalyzed by bismuth triflate under solvent-free conditions
-
Carbonyl compounds were converted to the corresponding 1,3-dioxolanes and 1,3-dioxanes with ethylene glycol and 1,3-propandiol in the presence of bismuth triflate under solvent-free conditions. In addition, high chemoselective protection of aldehydes in the presence of ketones has been achieved.
- Aliyan, Hamid,Fazaeli, Razieh,Massah, Ahmad Reza,Momeni, Ahmad Reza,Naghash, Hamid Javaherian,Moeinifard, Behzad
-
experimental part
p. 873 - 876
(2012/04/05)
-
- Highly efficient and chemoselective acetalization of carbonyl compounds catalyzed by new and reusab e zirconyl triflate, zr0(0tf)2
-
Various types of aromatic aldehydes were efficiently converted to their corresponding 1,3-dioxanes and 1,3-dioxolane with 1,3-propanediol and ethylene glycol, respectively, in the presence of catalytic amount of ZrO(OTf) 2 in acetonitrile at room temperature. The catalyst can be reused several times without loss of its catalytic activity. Very short reaction times, selective acetalization of aromatic aldehydes in the presence of aliphatic aldehydes and ketones, very mild reaction conditions, reusability of the catalyst, and easy workup are noteworthy advantages of this method.
- Moghadam, Majid,Mohammadpoor-Baltork, Iraj,Tangestaninejad, Shahram,Mirkhani, Valiollah,Yazdani, Parvin,Ghorjipoor, Saeedeh
-
experimental part
p. 131 - 135
(2009/09/30)
-
- Copper-catalyzed hydroalkylation of alkynes: Addition of sp3 C-H bonds across carbon-carbon triple bonds
-
The regioselective copper-catalyzed addition of sp3 C-H bonds adjacent to an oxygen atom to various alkynes has been accomplished under mild reactions conditions in the presence of tertbutyl hydroperoxide to give the corresponding alkenylated p
- Huang, Lehao,Cheng, Kai,Yao, Bangben,Zhao, Jinlong,Zhang, Yuhong
-
scheme or table
p. 3504 - 3510
(2010/02/28)
-
- Protection and deprotection of acetals by using MoO3/SiO 2
-
Acetalization of aldehydes using a new silica-supported molybdenum(VI) oxide (20%) catalyst has been explored. Additionally, facile deprotection strategy for the acetals is reported including the results from the replacement of solvent studies. The protocol achieved the protection O,O-acetals in excellent yield within a few hours under neutral conditions and also deprotection of aromatic O,O-acetals in excellent yields was achieved within a few minutes in aqueous acetone. Copyright Taylor & Francis Group, LLC.
- Bhosale, Rajesh S.,Bhosale, Sidhanath V.,Bhosale, Sheshanath V.,Solanke, Kuldeep S.,Pawar, Rajendra P.,Chougule, Harish S.,Dongare, Mohan K.
-
p. 659 - 663
(2007/10/03)
-
- The rapid photomediated alkenylation of 2-alkyl-1,3-dioxolanes with alkynes: A stereoelectronically assisted chain reaction
-
The photomediated reaction of alkynes such as DMAD with 1,3-dioxolanes leads to remarkably rapid alkenylation; evidence is presented that these reactions occur via a chain mechanism. The Royal Society of Chemistry 2006.
- Geraghty, Niall W. A.,Lally, Andrea
-
p. 4300 - 4302
(2007/10/03)
-
- Acidic properties of sulfonic acid-functionalized FSM-16 mesoporous silica and its catalytic efficiency for acetalization of carbonyl compounds
-
Propyl-sulfonic acid-functionalized FSM-16 mesoporous silica (SO 3H-FSM) is prepared by a conventional post-modification method. For the acetalization of carbonyl compounds with ethylene glycol, SO 3H-FSM shows a higher rate and 1,3-dioxolane yield than conventional heterogeneous solid acids such as zeolites, montmorillonite K10 clay, silica-alumina, and the sulfonic resin. SO3H-FSM is stable during the reaction, with no leaching and deactivation of sulfonic acid groups, and is reusable without loss of its activity. The acidity and hydrophilicity of SO 3H-FSM are well characterized by the microcalorimetry of NH 3 adsorption, NH3-TPD, and H2O-TPD, and the result is compared with those for various aluminosilicate zeolites (HZSM5, HBEA, HY) and K10 clay. It is found that NH3-TPD is not suitable for characterizing the acidity of SO3H-FSM, because the decomposition of SO3H groups on SO3H-FSM begins above 200°C. An NH 3 adsorption microcalorimetric experiment at 150°C shows that, compared with HZSM5, SO3H-FSM has a smaller number of acid sites but has a similar number of strong acid sites with ammonia adsorption heat above 140 kJ mol-1. Comparison of the structural properties and catalytic results shows that a large pore diameter and low hydrophilicity are required to obtain high activity. Bronsted acid sites with a relatively strong acid strength are more suitable for this reaction, but the high acid concentration is not indispensable. The high activity of SO3H-FSM should be caused by the presence of the strong Bronsted acid sites in the mesopore with a relatively low hydrophilicity, where both reactants can smoothly access the acid sites.
- Shimizu, Ken-Ichi,Hayashi, Eidai,Hatamachi, Tsuyoshi,Kodama, Tatsuya,Higuchi, Tomoya,Satsuma, Atsushi,Kitayama, Yoshie
-
p. 131 - 138
(2007/10/03)
-
- A remarkable iodine-catalyzed protection of carbonyl compounds
-
We report here a remarkably simple molecular iodine-catalyzed protection method for various carbonyl compounds as ketals in a general reaction. The iodine-catalyzed reaction of mandelic acid and lactic acid with several aldehydes has furnished a highly diastereoselective synthesis of cis and trans dioxolanones.
- Banik, Bimal K.,Chapa, Marin,Marquez, Jocabed,Cardona, Magda
-
p. 2341 - 2343
(2007/10/03)
-
- A simple and practical synthetic protocol for acetalisation, thioacetalisation and transthioacetalisation of carbonyl compounds under solvent-free conditions
-
A wide variety of carbonyl compounds can be converted smoothly to the corresponding acetals on treatment with alcohols or diols and triethyl orthoformate in the presence of a catalytic amount of (bromodimethyl)sulfonium bromide at room temperature. Similarly, various carbonyl compounds can be transformed into the corresponding dithioacetals on reaction with thiol or dithiols at room temperature by employing the same catalyst without any solvent. Moreover, O,O-acetals can also be converted into the corresponding dithioacetals under identical conditions. Some of the major advantages are mild reaction conditions, a high degree of efficiency, compatibilty with other protecting groups and the lack of solvents, particularly for thioacetalisation. In addition, no brominations occur at the double bond or α to the keto position or even in the aromatic ring under these experimental conditions. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.
- Khan, Abu T.,Mondal, Ejabul,Ghosh, Subrata,Islam, Samimul
-
p. 2002 - 2009
(2007/10/03)
-
- Polyaniline-Supported Sulfuric Acid Salt as a Powerful Catalyst for the Protection and Deprotection of Carbonyl Compounds
-
Structurally different carbonyl compounds were converted into their corresponding cyclic acetals using polyaniline-sulfate salt as catalyst in dry toluene in excellent yield. In turn, useful deacetalization in aqueous medium was demonstrated. Chemoselective protection of carbonyl compounds was also demonstrated. The advantages of the polyaniline-sulfate salt are ease of preparation and handling, stability, reusability and activity.
- Palaniappan, Srinivasan,Narender, Puli,Saravanan, Chandrasekaran,Rao, Vaidya Jayathirtha
-
p. 1793 - 1796
(2007/10/03)
-
- Convenient preparation of cyclic acetals, using diols, TMS-source, and a catalytic amount of TMSOTf
-
With use of diol, alkoxysilane, and a catalytic amount of trimethylsilyl trifluoromethanesulfonate (TMSOTf), carbonyl compounds are converted to acetals in good yields under mild conditions. This procedure, which was carried out without synthesizing the silylated diols, is a more convenient adaptation of Noyori's method. This acetalization applies to not only simple but also conjugated carbonyl compounds. Moreover, various TMS compounds, including solid supported compounds, are effective for this method instead of alkoxylsilane.
- Kurihara, Masaaki,Hakamata, Wataru
-
p. 3413 - 3415
(2007/10/03)
-
- A remarkable bismuth nitrate-catalyzed protection of carbonyl compounds
-
Bismuth nitrate has been found to be an outstanding catalyst for the protection of carbonyl compounds as acetal, ketal, mixed ketal and thioketal with an excellent yield.
- Srivastava, Neeta,Dasgupta, Swapan K.,Banik, Bimal K.
-
p. 1191 - 1193
(2007/10/03)
-
- A novel approach of cycloaddition of difluorocarbene to α-β-unsaturated aldehydes and ketones: Synthesis of gem-difluorocyclopropyl ketones and 2-fluorofurans
-
A series of gem-difluorocyclopropyl acetals and ketals are easily obtained in moderate yields from the [1 + 2] cycloaddition of difluorocarbene to 1,3-dioxolanes of α,β-unsaturated aromatic aldehydes and ketones. Hydrolysis of these fluorinated compounds under acidic conditions either gives the corresponding gem-difluorocyclopropyl ketones or 1-aryl-2-fluorofuran derivatives through intramolecular carbonium rearrangement with simultaneous ring cleavage.
- Xu, Wei,Chen, Qing-Yun
-
p. 1151 - 1156
(2007/10/03)
-
- Two carbon homologated α,β-unsaturated aldehydes from alcohols using the in situ oxidation-Wittig reaction
-
The in situ oxidation-Wittig reaction, followed by subsequent hydrolysis, has been applied to the conversion of primary alcohols into α,β -unsaturated aldehydes. This conversion, which proceeds via the intermediacy of the homologated unsaturated dioxolanes, gives good to excellent yields with a range of benzylic alcohols and heterocyclic methanols.
- Reid, Mark,Rowe, David J.,Taylor, Richard J. K.
-
p. 2284 - 2285
(2007/10/03)
-
- Improved one-pot synthesis of styryl tetrahydrofurans and cyclohexanes by radical addition to β-nitrostyrenes in the presence of benzoyl peroxide
-
Stereoselective styryl derivatives have been prepared based on radical substitution (addition-elimination) of heterocycles or cyclohydrocarbons units to (E)-β-nitrostyrenes 1 using a common radical initiator benzoyl peroxide. High reactivity and selectivity with wide substrate scope were attained by using this easy methodology. The reactions using easily obtained and one-pot potential starting materials gave excellent trans-selectivity with medium to high yields in all cases. Synthetic utility of this approach has been demonstrated by the preparation of various trans-styryl derivatives.
- Jang, Yeong-Jiunn,Shih, Yuh-Kuo,Liu, Jing-Yuan,Kuo, Wen-Yu,Yao, Ching-Fa
-
p. 2123 - 2128
(2007/10/03)
-
- Catalytic asymmetric epoxidation
-
A compound and method for producing an enantiomerically enriched epoxide from an olefin using a chiral ketone and an oxidizing agent is disclosed.
- -
-
Page column 28
(2010/01/30)
-
- 2,4,4,6-Tetrabromo-2,5-cyclohexadienone (TABCO) as a versatile, efficient, and chemoselective catalyst for the acetalization and transacetalization of carbonyl compounds, the preparation of acetonides from epoxides and acylals (1,1-diacetates) from aldehydes
-
The efficient and chemoselective preparation of acetals and ketals from carbonyl compounds, transacetalization reactions, the conversion of epoxides to acetonides, and the preparation of acylals from aldehydes in the presence of catalytic amounts of 2,4,4,6-tetrabromo-2,5-cyclohexadienone (TABCO) are described.
- Firouzabadi, Habib,Iranpoor, Nasser,Shaterian, Hamid Reza
-
p. 2195 - 2205
(2007/10/03)
-
- Tetrabutylammonium tribromide (TBATB) as an efficient generator of HBr for an efficient chemoselective reagent for acetalization of carbonyl compounds
-
Acyclic and cyclic acetals of various carbonyl compounds were obtained in excellent yields under a mild reaction condition in the presence of trialkyl orthoformate and a catalytic amount of tetrabutylammonium tribromide (TBATB) in absolute alcohol. Chemoselective acetalization of an aldehyde in the presence of ketone, unsymmetrical acetal formation, shorter reaction times, mild reaction conditions, the stability of acid-sensitive protecting groups, high efficiencies, facile isolation of the desired products, and the catalytic nature of the reagent make the present methodology a practical alternative.
- Gopinath, Rangam,Haque, Sk. Jiaul,Patel, Bhisma K.
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p. 5842 - 5845
(2007/10/03)
-
- Highly efficient heterogeneous acetalization of carbonyl compounds catalyzed by a titanium cation-exchanged montmorillonite
-
The titanium cation-exchanged montmorillonite efficiently catalyzed the selective acetalization of various carbonyl compounds as a recyclable solid acid. This heterogeneous catalyst has an advantage of a strikingly simple workup procedure over conventional homogeneous acids.
- Kawabata, Tomonori,Mizugaki, Tomoo,Ebitani, Kohki,Kaneda, Kiyotomi
-
p. 8329 - 8332
(2007/10/03)
-
- Eco-friendly Pt-Mo/ZrO2 solid acid catalyst for selective protection of carbonyl compounds
-
An easy method for protection of carbonyl compounds has been carried out in excellent yields under catalysis of Pt-Mo/ZrO2 in toluene at 383 K.
- Reddy,Reddy,Giridhar
-
p. 1819 - 1823
(2007/10/03)
-
- Silica gel-supported metallic sulfates catalyzed chemoselective acetalization of aldehydes under microwave irradiation
-
Silica gel - supported metallic sulfates are found to be efficient catalysts for the protection of both aromatic and aliphatic aldehydes as 1,3- dioxolanes under microwaves in solvent-free conditions. Due to the neutral reaction conditions, this method is compatible with acid sensitive substrates.
- Yadav,Reddy, B. V. Subba,Srinivas,Ramalingam
-
p. 701 - 703
(2007/10/03)
-
- Cadmium iodide catalyzed and efficient synthesis of acetals under microwave irradiations
-
A new selective method of acetalization of aldehydes and ketones with 1,2-diols, 1,3-diols or alcohols mediated by cadmium iodide under microwave irradiation is achieved in excellent yields.
- Laskar, Dhrubojyoti Dey,Prajapati, Dipak,Sandhu, Jagir S.
-
p. 1283 - 1284
(2007/10/03)
-
- Studies in Lewis acid and LiClO4 (or Nafion-H) catalysed ionic Diels- Alder reactions of chiral and achiral olefinic acetals respectively
-
Chiral olefinic acetals derived from crotonaldehyde undergo ionic Diels- Alder reaction giving the corresponding cycloadducts in moderate to good diastereoselectivities. A variety of achiral olefinic acetals react with isoprene and cyclopentadiene to form the cycloadducts in good to excellent yields when catalysed by 4M LiClO4 in nitromethane or by Nafion-H in dichloromethane.
- Kumareswaran,Vankar, Padmar S.,Reddy, M. Venkat Ram,Pitre, Sangeeta V.,Raja, Roy,Vankar, Yashwant D.
-
p. 1099 - 1110
(2007/10/03)
-
- Acetalization of α,β-unsaturated carbonyl compounds catalyzed by complexes of Pt(II)
-
A class of cationic diphosphine complexes of Pt(II) are sufficiently Lewis acidic to catalyze the acetalization of aldehydes and ketones. α,β-Unsaturated substrates can be easily acetalized with ethylene glycol under mild conditions in high yield and avoiding side reactions leading to formation of undesired by-products arising from the nucleophilic addition to the carbon-carbon double bond conjugated to the carbonyl group. A comparison of the behavior of a Pt complex with respect to PTSA as catalysts under identical conditions shows the superior selectivity of the former in many cases.
- Nieddu, Enrico,Cataldo, Maurizio,Pinna, Francesco,Strukul, Giorgio
-
p. 6987 - 6990
(2007/10/03)
-
- Palladium-catalysed substitution reactions of geminal allylic diacetates
-
The Pd(0)-catalysed substitution of allylic 1,1-diacetates by both carbon and oxygen nucleophiles is described. The products isolated resulted from either single or double substitution reactions.
- Van Heerden, Fanie R.,Huyser, Johan J.,Williams, D. Bradley G.,Holzapfel, Cedric W.
-
p. 5281 - 5284
(2007/10/03)
-
- Phase transfer Wittig reaction with 1,3-dioxolan-2-yl-methyltriphenyl phosphonium salts: An efficient method for vinylogation of aromatic aldehydes
-
Aldehydes were efficiently transformed into allylic dioxolanes by a Wittig-type reaction, using 1,3-dioxolan-2-yl-methyltriphenylphosphonium bromide under phase transfer conditions. The substituent kinetic effects were studied, and related to Hammett values and electrochemical potentials.
- Daubresse, Nicolas,Francesch, Charlette,Rolando, Christian
-
p. 10761 - 10770
(2007/10/03)
-
- Selective Catalytic Transesterification, Transthiolesterification, and Protection of Carbonyl Compounds over Natural Kaolinitic Clay
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Transesterification and transthiolesterification of β-keto esters with variety of alcohols and thiols and selective protection of carbonyl functions with various protecting groups catalyzed by natural kaolinitic clay are described. The clay has been found to be an efficient catalyst in transesterifying long chain alcohols, unsaturated alcohols, and phenols to give their corresponding β-keto esters in high yields. For the first time, transthiolesterification of β-keto esters with a variety of thiols has been achieved under catalytic conditions. Clay also catalyzes selective transesterification of β-keto esters by primary alcohols in the presence of secondary and tertiary alcohols giving corresponding β-keto esters. A systematic study involving the reactivity of different nucleophiles (alcohols, amines, and thiols) toward β-keto esters is also described. Sterically hindered carbonyl groups as well as α,β-unsaturated carbonyl groups underwent protection without the deconjugation of the double bond. Chemoselective protection of aldehydes in the presence of ketones has also been achieved over natural kaolinitic clay.
- Ponde, Datta E.,Deshpande, Vishnu H.,Bulbule, Vivek J.,Sudalai, Ammugam,Gajare, Anil S.
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p. 1058 - 1063
(2007/10/03)
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- Solvent free protection of carbonyl group under microwave irradiation
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Protection of aldehydes and ketones as acetals or dioxolanes catalysed by PTSA or KSF clay was readily achieved from orthoformates, 1,2-ethanediol or 2,2-dimethyl-1,3-dioxolane without solvent under microwave irradiation.
- Perio, Bertrand,Dozias, Marie-Joelle,Jacquault, Patrick,Hamelin, Jack
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p. 7867 - 7870
(2007/10/03)
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- Natural kaolinitic clay: A remarkable reusable solid catalyst for the selective functional protection of aldehydes and ketones
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Natural kaolinitic clay possessing transition metals such as Fe and Ti in its lattice has been found to catalyze efficiently the chemoselective acetalization and thioacetalization of variety of carbonyl compounds with ethane - 1,2 - diol and ethane - 1,2 - dithiol respectively.
- Ponde, Datta,Borate,Sudalai,Ravindranathan,Deshpande
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p. 4605 - 4608
(2007/10/03)
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- Nickel mdiated Double Bond formation from vic-Dibromides and Ethyl Magnesium Bromide
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vic-dibromides are quantitaively converted into alkenes by using a catalityc amount of NidppeCl2 in the presence of two molar equivalents of EtMgBr in THF.Stereochemical aspects of the reaction are given.
- Malanga, Corrado,Aronica, Laura A.,Lardicci, Luciano
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p. 9189 - 9192
(2007/10/02)
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- Microwave promoted acetalization of aldehydes and ketones
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Aldehydes and ketones are readily acetalized under microwave irradiation with ethylene glycol in the presence of p-toluenesulfonic acid(PTSA), ferric(III) chloride or acidic alumina.
- Moghaddam,Sharifi
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p. 2457 - 2461
(2007/10/02)
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- Synthesis of 1,3-dioxolanes catalysed by AlPO4 and AlPO4-Al2O3: kinetic and mechanistic studies
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A number of aldehydes and ketones were easily and quantitatively converted to the corresponding 1,3-dioxolanes by the reaction with ethylene glycol over four synthetic amorphous AlPO4 and AlPO4-Al2O3 catalysts using acetonitrile as the solvent at different temperatures in the range 30-60 deg C without the formation of any by-product.The influence of the number of acid sites on the catalyst surface as well as the substituent effects of different carbonyl compounds studied can be evaluated through several isokinetic parameters obtained owing to the existence of a linearfree-energy relationship (LFER).The results obtained account for an intermediate in the transition state whose relative stability is determined by the resonance between the carbonyl group and their substituents, but its evolution is via a concerted process in two adsorption-desorption steps.
- Bautista, Felipa M.,Campelo, Juan M.,Garcia, Angel,Leon, Josefa,Luna, Diego,Marinas, Jose M.
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p. 815 - 822
(2007/10/02)
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- Distannoxane-catalyzed acetilization of carbonyls
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1,3-Disubstituted tetrabutyldistannoxanes catalyze acetilization of carbonyl compounds under mild conditions. Thorough investigations of factors influencing this reaction are given. A variety of synthetically useful carbonyl compounds are efficiently converted to acetals. In particular, acetilization of cyclic α,β-unsaturated ketones is readily achieved which have met with only limited success so far.
- Otera, Junzo,Dan-oh, Nobuhisa,Nozaki, Hitosi
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p. 1449 - 1456
(2007/10/02)
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- A Comparison of (Chloromethyl)- and (Iodomethyl)zinc Cyclopropanation Reagents
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A study comparing the rate of cyclopropanation of a range of olefins using (chloromethyl)- and (iodomethyl)zinc reagents is described.The (chloromethyl)zinc reagent derived from diethylzinc and chloroiodomethane is generally more reactive than the (iodomethyl)zinc analogue.The use of 1,2-dichloroethane as the solvent for these reactions was shown to be a crucial factor necessary to achieve clean, rapid, high-yielding cyclopropanations.The well-known directing effect of proximal oxygen substituents on the stereochemical outcome of "Simmons-Smith" cyclopropanations was shown to hold for the (chloromethyl)zinc reagent as well.The diethylzinc/chloroiodomethane reagent system in 1,2-dichloroethane should prove to be a valuable alternative to traditional (iodomethyl)zinc-based cyclopropanation reagents.
- Denmark, Scott E.,Edwards, James P.
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p. 6974 - 6981
(2007/10/02)
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- 70. Cationic Palladium(II), Platinum(II), and Rhodium(I) Complexes as Acetalisation Catalysts
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The use of (CF3SO3)2 as a catalyst for the acetalisation of a variety of aldehydes and ketones and for trans-acetalisation is described.It is also shown that (CF3SO3)2 is at least as effective as the corresponding Pd compound, while much lower reaction rates are observed with
- Gorla, Fabrizio,Venanzi, Luigi M.
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p. 690 - 697
(2007/10/02)
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