- Formation of dioxolane on the surface of silica-sulphuric acid in dry media - Chemoselective protection of aryl aldehydes
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Chemoselective protection of aryl aldehydes can be accomplished through the formation of dioxolane on the surface of silica-sulphuric acid under solvent-free conditions where aliphatic aldehydes, dialkyl ketones, aryl alkyl ketones, and diaryl ketones rem
- Saha, Manabendra,Roy, Sanchita,Chaudhuri, Subrata Kumar,Bhar, Sanjay
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Read Online
- Preparation of aromatic ethers and dioxolanes under microwave irradiation
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Aromatic ethers and dioxolane derivatives were prepared in a domestic microwave oven adapted with a Dean-Stark collector. The reactions under microwave heating were shorter in duration than the reactions in conventional methods, confirming the potentiality of microwave energy in liquid chemical preparations.
- Salmoria,Neves,Dall'Oglio,Zucco
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Read Online
- Structure and surface properties of Ni-Al hydrotalcite-like compounds and their catalytic application in highly selective acetalization at room temperature
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Ni-Al hydrotalcite-like compounds (Ni-Al HTLCs) containing nitrate anions were synthesized and applied in the acetalization ofp-anisaldehyde with ethylene glycol under mild reaction conditions. The Ni-Al HTLCs showed good selectivity for acetalization and
- Cheng, Shu-Yan,Kou, Jia-Wei,Sun, Kai
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Read Online
- Synthesis and IR spectroelectrochemical studies of a [60] fulleropyrrolidine-(tricarbonyl)chromium complex: Probing C60 redox states by IR spectroscopy
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The synthesis of a new fulleropyrrolidine-(tricarbonyl)chromium complex: 1-methyl-2-(4-methoxyphenyl)-3,4-[60]fulleropyrrolidine-(tricarbonyl)chromium is described together with its characterization by IR, NMR and cyclic voltammetry. IR spectro-electroche
- Andersson, Claes-Henrik,Berggren, Gustav,Ott, Sascha,Grennberg, Helena
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- Inhibition by Water during Heterogeneous Br?nsted Acid Catalysis by Three-Dimensional Crystalline Organic Salts
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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
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p. 6364 - 6372
(2021/10/20)
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- Application of poly(Vinylbenzyltrimethylammonium tribromide) resin as an efficient polymeric catalyst in the acetalization and diacetylation of benzaldehydes
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The applications of a new supported tribromide reagent (poly(vinylbenzyltrimethylammonium tribromide) resin) were reported. This supported tribromide resin was used as a catalyst in the acetalization and diacetylation of benzaldehydes under mild conditions with high efficiency. The effects of solvents, and amount of the supported tribromide resin on the reactions were investigated. Under the optimal conditions, most of acetal and 1,1-diacetates of benzaldehydes were selectively obtained in excellent yields.
- Han, Bingbing,Hu, Junjun,Li, Xianwei,Zheng, Zubiao
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supporting information
p. 287 - 293
(2021/04/28)
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- Alcohol Etherification via Alkoxy Radicals Generated by Visible-Light Photoredox Catalysis
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A mechanistically divergent method is described that, employing a commercially available hypervalent iodine(III) reagent, generates alkoxy radicals from 1°, 2°, and 3° alcohols and allows their use in the functionalization of C(sp3)-H and C(sp2)-H bonds. This visible-light photoredox catalysis produces alkyl ethers via 1,5/6-hydrogen atom transfer or aryl ethers via 1,5-addition. This mild methodology provides a practical strategy for the synthesis of acetals, orthoesters, tetrahydrofurans, and chromanes.
- Rivero, Alexandra R.,Fodran, Peter,Ondrejková, Alica,Wallentin, Carl-Johan
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supporting information
p. 8436 - 8440
(2020/11/03)
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- Chemoselective Nucleophilic Functionalizations of Aromatic Aldehydes and Acetals via Pyridinium Salt Intermediates
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The development of a novel chemoselective functionalization can diversify the strategy for synthesizing the target molecules. The perfect chemoselectivity between aromatic and aliphatic aldehydes is difficult to achieve by the previous methods. The aromatic aldehyde-selective nucleophilic addition in the presence of aliphatic aldehydes was newly accomplished. Namely, the aromatic aldehyde-selective nucleophilic addition using arenes and allyl silanes proceeded in the presence of trialkylsilyl triflate and 2,2′-bipyridyl, while the aliphatic aldehydes completely remained unchanged. The reactive pyridinium-type salt intermediate derived from an aromatic aldehyde chemoselectively underwent the nucleophilic substitution. Moreover, the aromatic acetals as the protected aldehydes could be directly transformed into similar pyridinium salt intermediates, which reacted with various nucleophiles coexisting with the aliphatic aldehydes.
- Kawajiri, Takahiro,Kato, Maho,Nakata, Hiroki,Goto, Ryota,Aibara, Shin-Yo,Ohta, Reiya,Fujioka, Hiromichi,Sajiki, Hironao,Sawama, Yoshinari
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p. 3853 - 3870
(2019/03/07)
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- Highly regioselective α-formylation and α-acylation of BODIPY dyes via tandem cross-dehydrogenative coupling with in situ deprotection
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A metal-free C-H formylation and acylation of BODIPY dyes using a variety of dioxolane derivatives as aldehyde equivalents is reported, providing a postfunctionalization method for controllable synthesis of BODIPYs with carbonyl groups at 3,5-positions vi
- Lv, Fan,Yu, Yang,Hao, Erhong,Yu, Changjiang,Wang, Hua,Boens, No?l,Jiao, Lijuan
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supporting information
p. 5121 - 5128
(2019/05/29)
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- Utilization of 1,3-Dioxolanes in the Synthesis of α-branched Alkyl and Aryl 9-[2-(Phosphonomethoxy)Ethyl]Purines and Study of the Influence of α-branched Substitution for Potential Biological Activity
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Syntheses of α-branched alkyl and aryl substituted 9-[2-(phosphonomethoxy)ethyl]purines from substituted 1,3-dioxolanes have been developed. Key synthetic precursors, α-substituted dialkyl [(2-hydroxyethoxy)methyl]phosphonates were prepared via Lewis acid mediated cleavage of 1,3-dioxolanes followed by reaction with dialkyl or trialkyl phosphites. The best preparative yields were achieved under conditions utilizing tin tetrachloride as Lewis acid and triisopropyl phosphite. Attachment of purine bases to dialkyl [(2-hydroxyethoxy)methyl]phosphonates was performed by Mitsunobu reaction. Final α-branched 9-[2-(phosphonomethoxy)ethyl]purines were tested for antiviral, cytostatic and antiparasitic activity, the latter one determined as inhibitory activity towards Plasmodium falciparum enzyme hypoxanthine-guanine-xanthine phosphoribosyltransfesase. In most cases biological activity was only marginal.
- Pomeisl, Karel,Pohl, Radek,Snoeck, Robert,Andrei, Graciela,Kre?merová, Marcela
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p. 119 - 156
(2019/01/04)
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- Acid properties of organosiliceous hybrid materials based on pendant (fluoro)aryl-sulfonic groups through a spectroscopic study with probe molecules
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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
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p. 6308 - 6317
(2019/11/20)
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- Synthesis of dioxolanes and oxazolidines by silica gel catalysis
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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.
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p. 1429 - 1436
(2018/06/25)
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- Hierarchical porous organic polymer as an efficient metal-free catalyst for acetalization of carbonyl compounds with alcohols
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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
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- Mild, Redox-Neutral Formylation of Aryl Chlorides through the Photocatalytic Generation of Chlorine Radicals
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We report a redox-neutral formylation of aryl chlorides that proceeds through selective 2-functionalization of 1,3-dioxolane through nickel and photoredox catalysis. This scalable benchtop approach provides a distinct advantage over traditional reductive carbonylation in that no carbon monoxide, pressurized gas, or stoichiometric reductant is employed. The mild conditions give unprecedented scope from abundant and complex aryl chloride starting materials.
- Nielsen, Matthew K.,Shields, Benjamin J.,Liu, Junyi,Williams, Michael J.,Zacuto, Michael J.,Doyle, Abigail G.
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supporting information
p. 7191 - 7194
(2017/06/13)
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- From solution to in-cell study of the chemical reactivity of acid sensitive functional groups: A rational approach towards improved cleavable linkers for biospecific endosomal release
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pH-Sensitive linkers designed to undergo selective hydrolysis at acidic pH compared to physiological pH can be used for the selective release of therapeutics at their site of action. In this paper, the hydrolytic cleavage of a wide variety of molecular structures that have been reported for their use in pH-sensitive delivery systems was examined. A wide variety of hydrolytic stability profiles were found among the panel of tested chemical functionalities. Even within a structural family, a slight modification of the substitution pattern has an unsuspected outcome on the hydrolysis stability. This work led us to establish a first classification of these groups based on their reactivities at pH 5.5 and their relative hydrolysis at pH 5.5 vs. pH 7.4. From this classification, four representative chemical functions were selected and studied in-vitro. The results revealed that only the most reactive functions underwent significant lysosomal cleavage, according to flow cytometry measurements. These last results question the acid-based mechanism of action of known drug release systems and advocate for the importance of an in-depth structure-reactivity study, using a tailored methodology, for the rational design and development of bio-responsive linkers.
- Jacques, Sylvain A.,Leriche, Geoffray,Mosser, Michel,Nothisen, Marc,Muller, Christian D.,Remy, Jean-Serge,Wagner, Alain
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supporting information
p. 4794 - 4803
(2016/06/13)
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- New Br?nsted-Lewis acidic quaternary ammonium ionic liquids: Synthesis, acidity determination and acidity-catalytic activity relationship
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A series of new Br?nsted-Lewis acidic ionic liquids, which are operational simplicity, high stability, low cost and applicable for scaling up, have been synthesized and their activity for acetalization was examined. The comprehensive studies on the acidity-catalytic performance relationship of the Br?nsted-Lewis acidic ionic liquids were performed. IR spectroscopy results confirmed that the new Br?nsted-Lewis acidic ionic liquids possess both Br?nsted and Lewis acid sites. The acidities were determined by Hammett method, and further studies on acidity-activity relationship revealed that the acidity played a key role in the acid-catalyzed probe reactions.
- Yi, Fengping,Gao, Jie,Zhang, Lirong,Jiang, Xiaoyan
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p. 1260 - 1264
(2015/02/19)
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- Tandem catalysis by palladium nanoclusters encapsulated in metal-organic frameworks
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A bifunctional Zr-MOF catalyst containing palladium nanoclusters (NCs) has been developed. The formation of Pd NCs was confirmed by transmission electron microscopy (TEM) and extended X-ray absorption fine structure (EXAFS). Combining the oxidation activity of Pd NCs and the acetalization activity of the Lewis acid sites in UiO-66-NH2, this catalyst (Pd@UiO-66-NH2) exhibits excellent catalytic activity and selectivity in a one-pot tandem oxidation-acetalization reaction. This catalyst shows 99.9% selectivity to benzaldehyde ethylene acetal in the tandem reaction of benzyl alcohol and ethylene glycol at 99.9% conversion of benzyl alcohol. We also examined various substituted benzyl alcohols and found that alcohols with electron-donating groups showed better conversion and selectivity compared to those with electron-withdrawing groups. We further proved that there was no leaching of active catalytic species during the reaction and the catalyst can be recycled at least five times without significant deactivation.
- Li, Xinle,Guo, Zhiyong,Xiao, Chaoxian,Goh, Tian Wei,Tesfagaber, Daniel,Huang, Wenyu
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p. 3490 - 3497
(2015/02/19)
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- One-pot synthesis of ordered mesoporous zirconium oxophosphate with high thermostability and acidic properties
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A series of mesoporous zirconium oxophosphate (M-ZrPO) with different P/Zr molar ratios (0-1.25) has been prepared via a facile one-pot evaporation-induced self-assembly (EISA) strategy. After removing the structure-directing agents, the M-ZrPO with large specific surface area (160 m2 g-1), big pore volume (0.26 cm3 g-1) and narrow pore size distribution (5.64 nm) has been obtained. Small-angle X-ray diffraction (SXRD) and transmission electron microscopy (TEM) results showed that these materials had ordered mesoporous structure. With the increase of P/Zr, the textural properties of M-ZrPO could be improved. Moreover, the ordered mesostructure could be maintained even when treated at 800°C, indicating the M-ZrPO had attractive thermal stability. NH3-TPD and pyridine-IR analyses showed the presence of abundant Broensted and Lewis acid sites in the material. The M-ZrPO has been used successfully as solid acid catalyst and showed excellent performance in the ketalization reaction.
- Miao, Zhichao,Xu, Leilei,Song, Huanling,Zhao, Huahua,Chou, Lingjun
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p. 1942 - 1954
(2013/07/26)
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- Facile aldolization catalyzed by ionic liquid [4-sulfbmpyrazine][BF 4]
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The acidic functionalized ionic liquid 1-(4-sulfonic group)butyl-3- methylpyrazine tetrafluoroborate (abbreviated as [4-sulfbmpyrazine][BF 4]) was employed as the catalyst of the condensation of aromatic aldehyde and diols. The optimized condition was as follows: aromatic aldehyde (0.20 mol), diols (0.30 mol) and [4-sulfbmpyrazine][BF4] (0.60 g) were refluxed in cyclohexane (10.00 mL) for 1 h. A series of aromatic aldehydes were studied and afforded the corresponding acetals products with good yields which were from 70.3 to 96.9 %. The ionic liquid catalyst could be recycled for four times without significant loss of catalyst reactivity.
- Zou, Jianzhong,Yi, Fengping,Zhang, Lirong,Wang, Zhen
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p. 6643 - 6646
(2013/07/26)
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- Homologative trifluoromethylation of acetals
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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.
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p. 1857 - 1862
(2013/07/26)
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- Synthesis of novel solid acidic ionic liquid polymer and its catalytic activities
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The novel solid acidic ionic liquid polymer has been synthesized through the copolymerization of acidic ionic liquid oligomers and resorcinol- formaldehyde (RF resin). The catalytic activities were investigated through the acetalization. The results showed that the PIL was very efficient for the reactions with the average yield over 99.0%. The procedure was quite simple with just one-step to complete both the reactions. The high hydrophobic BET surface, high catalytic activities and high stability gave the PIL great potential for green chemical processes. Pleiades Publishing, Ltd., 2013.
- Liang, Xuezheng
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p. 724 - 729
(2014/01/23)
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- Bis(perfluorooctanesulfonyl)imide supported on fluorous silica gel: Application to protection of carbonyls
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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
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experimental part
p. 121 - 126
(2012/08/28)
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- Synthesis of a novel ionic liquid with both Lewis and Br?nsted acid sites and its catalytic activities
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The novel ionic liquid with both Lewis and Br?nsted acid sites has been synthesized and its catalytic activities for acetalization and Michael addition were investigated carefully. The novel ionic liquid was stable to water and could be used in aqueous solution. Furthermore, the molar ratio of the Lewis and Br?nsted acid sites could be adjusted according to different reactions. The results showed that the novel ionic liquid was very efficient for the traditional acid-catalyzed reactions with good to excellent yields in short time.
- Liang, Xuezheng,Qi, Chenze
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experimental part
p. 808 - 812
(2012/01/04)
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- Bismuth compounds in organic synthesis: Synthesis of dioxanes, dioxepines, and dioxolanes catalyzed by bismuth(III) triflate
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A simple method for the synthesis of 1,3-dioxolanes from carbonyl compounds has been developed using 1,2-bis(trimethylsilyloxy)ethane in the presence of bismuth(III) triflate as a catalyst. The bismuth(III) triflate catalyzed synthesis of a range of dioxanes and dioxepines has also been developed. In these latter cases, the carbonyl compound is treated with a diol, and triethyl orthoformate is used as a water scavenger. All these methods avoid the use of a Dean-Stark trap. Georg Thieme Verlag Stuttgart.
- Podgorski, Daniel M.,Krabbe, Scott W.,Le, Long N.,Sierszulski, Paul R.,Mohan, Ram S.
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experimental part
p. 2771 - 2775
(2010/10/02)
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- Acetalization of carbonyl compounds catalyzed by bismuth triflate under solvent-free conditions
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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
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experimental part
p. 873 - 876
(2012/04/05)
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- Highly efficient and chemoselective acetalization of carbonyl compounds catalyzed by new and reusab e zirconyl triflate, zr0(0tf)2
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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
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experimental part
p. 131 - 135
(2009/09/30)
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- Mild and efficient chemoselective synthesis of acetals and geminal diacetates (acylals) from aldehydes using lanthanum(III) nitrate hexahydrate
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A mild and efficient chemoselective method has been developed for the preparation of acetals and gem-diacetates in good to excellent yields through a reaction of aldehydes with ethlyleneglycol or acetic anhydride using catalytic amounts of lanthanum(III) nitrate hexahydrate as a catalyst under solvent-free conditions. Copyright Taylor & Francis Group, LLC.
- Srinivasulu,Suryakiran,Rajesh,Malla Reddy,Venkateswarlu
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p. 1753 - 1759
(2008/09/20)
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- Indium(III)trifluoromethanesulfonate as a mild, efficient catalyst for the formation of acetals and ketals in the presence of acid sensitive functional groups
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Aldehydes and ketones, including acetophenone and benzophenone, are readily protected under mild, neutral conditions in the presence of various alcohols or orthoformates and catalytic amounts of indium(III) trifluoromethanesulfonate (0.8 mol %) under either room temperature or mild heating conditions to give the corresponding cyclic and acyclic acetals and ketals in good to excellent yields. Acid sensitive functional groups, N-Boc, THP, and TBDMS do not undergo competitive deprotection under the reported conditions.
- Gregg, Brian T.,Golden, Kathryn C.,Quinn, John F.
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p. 3287 - 3295
(2008/09/21)
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- A green procedure for the protection of carbonyl compounds catalyzed by iodine in ionic liquid
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Aldehydes and ketones are protected with ethylene glycol in the presence of a catalytic amount of iodine in PEG ionic liquid (IL 400) under mild conditions to afford the corresponding ketals in good yields. The recovery of iodine is facilitated by the ionic liquid. The recovered catalyst was reused six times with consistent activity.
- Ren, Yi-Ming,Cai, Chun
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body text
p. 7110 - 7112
(2015/04/15)
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- Protection and deprotection of acetals by using MoO3/SiO 2
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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.
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p. 659 - 663
(2007/10/03)
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- A remarkable iodine-catalyzed protection of carbonyl compounds
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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
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p. 2341 - 2343
(2007/10/03)
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- Acidic properties of sulfonic acid-functionalized FSM-16 mesoporous silica and its catalytic efficiency for acetalization of carbonyl compounds
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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
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p. 131 - 138
(2007/10/03)
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- Stripping off water at ambient temperature: Direct atom-efficient acetal formation between aldehydes and diols catalyzed by water-tolerant and recoverable vanadyl triflate
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(Chemical Equation Presented) Aromatic aldehydes can be readily protected as acetals with 1,2- and 1,3-diols by using vanadyl triflate as a catalyst in CH3CN at ambient temperature. Carbohydrate-based 1,2- and 1,3-diols can similarly be protected in good to excellent yields. The catalyst can be readily recovered from the aqueous layer. In combination with vanadyl triflate-catalyzed sequential regioselective, reductive acetal opening and chemoselective acylations, the title method allows for differential functionalization of all four hydroxyl units in a given glucopyranoside.
- Chen, Chien-Tien,Weng, Shiue-Shien,Kao, Jun-Qi,Lin, Chun-Cheng,Jan, Mi-Dan
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p. 3343 - 3346
(2007/10/03)
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- Non-acid catalytic acetalisation of aldehydes with diols in ionic liquids
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The acetalisation of aldehydes with diols to corresponding 1,3-dioxolanes has been accomplished using ionic liquids as catalyst and reaction media. In the reaction process the removal of water produced and other catalysts were not necessary. High conversion and good selectivity were obtained when using HMImBF4, which could be easily recycled and reused.
- Zhang, Fan,Xu, Dan-Qian,Luo, Shu-Ping,Liu, Bao-You,Du, Xiao-Hua,Xu, Zhen-Yuan
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p. 773 - 774
(2007/10/03)
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- Polyaniline-Supported Sulfuric Acid Salt as a Powerful Catalyst for the Protection and Deprotection of Carbonyl Compounds
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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
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p. 1793 - 1796
(2007/10/03)
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- A remarkable bismuth nitrate-catalyzed protection of carbonyl compounds
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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.
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p. 1191 - 1193
(2007/10/03)
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- Microwave promoted selective preparation of acetals and esters from aldehydes
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A new selective method of acetalization of aldehydes and cyclic ketones with 1,2-diols or alcohols catalyzed by iodine under microwave irradiation is reported. Depending upon the reaction conditions further oxidation of the arylidene acetals takes place in the system leading to the formation of products like iodoester 2 and hydroxy esters 3, 4 and 5. Both unsubstituted (1a) and substituted arylidene acetal with electron releasing group (1d) give high yield of iodoester 2 (70-80%) whereas the arylidene acetal substituted with an electron withdrawing group such as NO2 (1b) gives a low yield of the corresponding iodoester (2b, 25%).
- Borah, Ruli,Kalita, Dipok J.,Sarma, Jadab C.
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p. 1032 - 1038
(2007/10/03)
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- Tetrabutylammonium tribromide (TBATB) as an efficient generator of HBr for an efficient chemoselective reagent for acetalization of carbonyl compounds
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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)
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- Eco-friendly Pt-Mo/ZrO2 solid acid catalyst for selective protection of carbonyl compounds
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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
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p. 1819 - 1823
(2007/10/03)
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- 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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- A new selective catalytic acetalization method promoted by microwave irradiation
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A new selective method of acetalization of aldehydes and cyclic ketones with 1,2-diols or alcohols catalyzed by iodine under microwave irradiation is reported.
- Kalita, Dipok J.,Borah, Ruli,Sarma, Jadab C.
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p. 4573 - 4574
(2007/10/03)
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- Microwave-assisted acetalization of carbonyl compounds catalyzed by reusable Envirocat supported reagents
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Envirocat supported reagents (EPZG, EPZ10, and EPIC) are found to efficiently catalyze the acetalization of carbonyl compounds with 1,2-ethanediol under microwave irradiation under solvent-free conditions. The reagents can be used in repeated experiments to perform the reaction with the same activity.
- Beregszaszi, Timea,Molnar, Arpad
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p. 3705 - 3709
(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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- Reactions of Co-ordinated Ligands. Part 8. Reaction of Grignard Reagents with 2-Alkoxy-1,3-dioxolans; an Improved Route to Aldehydes
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The yields of 2-phenyl-1,3-dioxolan obtained from phenylmagnesium bromide and 2-alkoxy-1,3-dioxolans in which the type Men-O increase as the value of n proceeds along the series 4,3,1,2.Several Grignard reagents(including phenylmagnesium bromide) react with the 2-alkoxy-1,3-dioxolan in which n=2 to give the expected 2-substituted-1,3-dioxolans, whose yields are considerably higher than those of the diethyl acetals obtained from the corresponding reation with ethyl ortoformate.
- Houghton, Roy P.,Morgan, Alan D.
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p. 756 - 758
(2007/10/02)
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- Investigation of the Effectiveness of Various 1-Dialkylamino-1-methoxycarbenium-Methyl Sulfates in the Course of Acetalization
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The rate of dimethyl ketal formation from acetone and methanol in the presence of several 1-dialkylamino-1-methoxycarbenium methyl sulfates 1a, 5a-g is studied.The fastest rate was observed in the case of 5c.In the presence of 5c, the reaction of carbonyl compounds with either methanol or 1,2-diols gave the dimethyl ketals 6 and 1,3-dioxolanes 7, respectively.
- Kantlehner, Willi,Gutbrod, Heinz-Dieter,Funke, Bernd
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p. 246 - 252
(2007/10/02)
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