- Synthesis of DPA-triazole structures and their application as ligand for metal catalyzed organic reactions
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In this work, the use of DPA-triazole (DPA = dipicolylamine) molecules as ligands for metal catalyzed organic reactions has been investigated. A small library of ligands has been prepared by a CuAAC (click reaction) between propargyl-DPA and different azi
- Colombo Dugoni, Greta,Sacchetti, Alessandro,Urra Mancilla, Carolina
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- FLUORESCENT PROBE FOR ALDH3A1 DETECTION
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[Problem to be Solved] To provide a fluorescent probe for ALDH3A1 detection that can be used in flow cytometry adaptable to live cells. [Means of Resolution] A compound represented by general formula (I) or a salt thereof, wherein the compound or salt the
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-
Paragraph 0122
(2020/07/16)
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- Photochemical synthesis of acetals utilizing Schreiner's thiourea as the catalyst
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Acetalization of aldehydes is an area of great importance in Organic Chemistry for both synthetic and biological puproses. Herein, we report a mild, inexpensive and green photochemical protocol, where Schreiner's thiourea (N,N′-bis[3,5-bis(trifluoromethyl)-phenyl]-thiourea) is utilized as the catalyst and cheap household lamps as the light source. A variety of aromatic and aliphatic aldehydes were converted into acetals in good to high yields (23 examples, 36-96% yield) and an example of the synthesis of a cyclic acetal is provided. The reaction mechanism was also studied.
- Kokotos, Christoforos G.,Nikitas, Nikolaos F.,Spiliopoulou, Nikoleta
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supporting information
p. 3539 - 3545
(2020/06/25)
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- Preparation method of acetal or ketal compound
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The invention discloses a preparation method of an acetal or ketal compound. The preparation method comprises the following steps: oscillating aldehyde or ketone, alcohol and a catalyst at 60 DEG C, and carrying out post-treatment after the reaction is finished to obtain the acetal compound, wherein the catalyst comprises alpha-chymotrypsin, the aldehyde or ketone has a structure represented by acompound A, R1 and R2 are respectively and independently selected from aryl, H and alkyl, the alcohol has a structure represented by a compound B, and R3 is selected from saturated alkane. The preparation method provided by the invention is catalyzed by alpha-chymotrypsin, is mild in reaction condition, simple in operation process, low in cost and environment-friendly, and has popularization and application values.
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-
Paragraph 0021-0030
(2020/04/22)
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- α-Chymotrypsin-Induced Acetalization of Aldehydes and Ketones with Alcohols
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This is the first report of a simple and general method for acetalization of aldehydes via an α-chymotrypsin-induced reaction under mild conditions. A broad range of aromatic and heteroaromatic aldehydes have been acetalized under neutral conditions in good yields using a catalytic amount of chymotrypsin.
- Jiang, Guofang,Lan, Jin,Le, Zhanggao,Xie, Zongbo,Yang, Jiangnan,Zhu, Haibo
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p. 2121 - 2126
(2020/07/14)
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- Synthesis, structural determination and catalytic study of a new 2-D chloro-substituted zinc phosphate, (C8N2H20)[ZnCl(PO3(OH))]2
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A novel chloro-substituted zinc-phosphate, (C8N2H20)[ZnCl(PO3(OH))], has been synthesized by a slow evaporation method in the presence of 1,3-cyclohexanebis- (methylamine), which acts as a template. The structure consists of vertex linked ZnO3Cl and PO3(OH) tetrahedral, assembled into corrugated porous layers [ZnCl(PO3(OH))2]∞ with (4.82) topology. The optical properties were also investigated using Diffuse Reflecting Spectroscopy (DRS), showing that the title compound has semiconducting properties. In addition, the catalytic activity of (C8N2H20)[ZnCl(PO3(OH))]2 has been tested in the acetalisation reaction of aldehydes. The title compound displayed a high catalytic activity with practically total conversion in many examples using MeOD as solvent and as the sole source of acetalisation. More importantly, the reaction crudes are very clean and only the preferred products are found in the NMR spectra.
- Rayes, Ali,Herrera, Raquel P,Moncer, Manel,Ara, Irene,Calestani, Gianluca,Ayed, Brahim,Mezzadri, Francesco
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- Remote ‘Imidazole’ Based Ruthenium(II) p-Cymene Precatalyst for Selective Oxidative Cleavage of C?C Multiple Bonds
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The dual role of remote ‘imidazole’ attached with the precatalyst [(p-cymene)RuII(L)Y]+ (L=2-(4-substituted-phenyl)-1H-imidazo[4,5-f][1,10] phenanthroline, Y=chloride/solvent) was explored for the selective oxidative cleavage of C?C multiple bonds to acetals/aldehydes. The presence of ‘imidazole’ in the precatalysts was found to be useful for the activation of oxidant and release of p-cymene from the precatalysts, which in turn was not effective without the ‘imidazole’ moiety. The mechanistic aspects of the precatalyst were evaluated from spectroscopic, kinetic, and few other controlled experiments. The loss of p-cymene is the key step for the reaction and found to be faster in solvated precatalyst, [(p-cymene)RuII(L)(MeOH)]++ and thus showed 3–4-fold more effective as compared to [(p-cymene)RuII(L)Cl]+.
- Dutta, Manali,Bania, Kusum Kumar,Pratihar, Sanjay
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p. 2683 - 2694
(2019/05/24)
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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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- Formation of Acetals and Ketals from Carbonyl Compounds: A New and Highly Efficient Method Inspired by Cationic Palladium
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The development of a new, highly efficient, and simple method for masking carbonyl groups as acetals and ketals is described. This methodology relies on the nature of the palladium catalyst to direct the acetalization/ketalization reaction. This new protocol is mild and proceed with a very low catalyst loading at ambient temperatures. The method has been extended to a wide variety of different carbonyl compounds with various steric encumbrances to form the corresponding acetals and ketals in excellent yields.
- Green, Shawn D.,Kindoll, Tyler,Lazaro-Martinez, Brenda,Mensah, Enoch A.,West, Jesse
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p. 1810 - 1814
(2019/09/09)
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- Synthesis of (E)-α,β-unsaturated carboxylic esters derivatives from cyanoacetic acid via promiscuous enzyme-promoted cascade esterification/Knoevenagel reaction
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A new enzymatic protocol based on lipase-catalyzed cascade toward (E)-α,β-unsaturated carboxylic esters is presented. The proposed methodology consists of elementary organic processes starting from acetals and cyanoacetic acid leading to the formation of desired products in a cascade sequence. The combination of enzyme promiscuous abilities gives a new opportunity to synthesize complex molecules in the one-pot procedure. Results of studies on the influence of an enzyme type, solvent, and temperature on the cascade reaction course are reported. The presented methodology provides meaningful qualities such as significantly simplified process, excellent E-selectivity of obtained products and recycling of a biocatalyst.
- Wilk, Monika,Trzepizur, Damian,Koszelewski, Dominik,Brodzka, Anna,Ostaszewski, Ryszard
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- Unique chemoselective Mukaiyama aldol reaction of silyl enol diazoacetate with aldehydes and acetals catalyzed by MgI2 etherate
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Functionalized diazo acetoacetates are prepared by an efficient Mukaiyama aldol reaction between 3-TBSO-2-diazo-3-butenoate with aldehydes and acetals under mild reaction conditions. A variety of substituted aldehydes and the corresponding acetals are both accessible in good to excellent yields through this methodology. MgI2 etherate (MgI2·(OEt2)n) is the preferred catalyst and, the addition proceeds without decomposition of the diazo moiety. In addition, this MgI2·(OEt2)n-catalyzed Mukaiyama aldol reaction shows unique chemoselectivity towards aldehydes and acetals.
- Meng, Xiangwei,Pan, Haokun,Zhong, Tengjiang,Zhang, Xingxian
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- Nickel-Catalyzed Chemoselective Acetalization of Aldehydes With Alcohols under Neutral Conditions
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A molecularly defined NiII-complex catalyzing the chemoselective acetalization of aldehydes with alcohols under neutral conditions is reported. The reaction is general, efficient and showed a wide substrate scope (including aliphatic aldehydes) as well as excellent functional group tolerance. Reusability of the present nickel catalyst is also demonstrated.
- Subaramanian, Murugan,Landge, Vinod G.,Mondal, Akash,Gupta, Virendrakumar,Balaraman, Ekambaram
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supporting information
p. 4557 - 4562
(2019/08/30)
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- Photo-organocatalytic synthesis of acetals from aldehydes
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A mild and green photo-organocatalytic protocol for the highly efficient acetalization of aldehydes has been developed. Utilizing thioxanthenone as the photocatalyst and inexpensive household lamps as the light source, a variety of aromatic and aliphatic aldehydes have been converted into acyclic and cyclic acetals in high yields. The reaction mechanism was extensively studied.
- Nikitas, Nikolaos F.,Triandafillidi, Ierasia,Kokotos, Christoforos G.
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supporting information
p. 669 - 674
(2019/02/14)
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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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- Cobalt Nanoparticles Embedded in N-Doped Porous Carbon Derived from Bimetallic Zeolitic Imidazolate Frameworks for One-Pot Selective Oxidative Depolymerization of Lignin
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Cobalt nanoparticles embedded in N-doped porous carbon (Co@CN) were prepared by the pyrolysis of bimetallic zeolitic imidazolate frameworks (BMZIFs) based on ZIF-8 and ZIF-67. The catalyst shows excellent catalytic efficiency in one-pot selective oxidative cleavage of different linkages like β-O-4, a-O-4 and β-1 in organosolv lignin and lignin model compounds in the presence of oxygen (ambient pressure) under mild conditions (383 K). Compared with traditional supported catalyst, the catalyst gives a highly hollow structure, which favored the adsorption of substrates and oxygen. The uniform cobalt nanoparticles surrounded by N-doped graphitic structures and the strong electron transfer from graphitic nitrogen to Co NPs make it hard to be oxidized prior to use and higher catalytic reactivity. Moreover, the catalyst can be easily recovered by magnetic force after the reaction, and reused after reduction for five times without an obvious change in yields.
- Sun, Kangkang,Chen, Shujie,Zhang, Jiawei,Lu, Guo-Ping,Cai, Chun
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p. 1264 - 1271
(2019/02/01)
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- Access to Wieland-Miescher Diketone-Derived Building Blocks by Stereoselective Construction of the C-9 Quaternary Carbon Center Using the Mukaiyama Aldol Reaction
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The Mukaiyama aldol reaction has been used to efficiently install a lateral chain at the C-9 position of the Wieland-Miescher ketone derivative 3 within two steps, representing a shortcut compared to that of the classical sequences. The treatment of the silylated enol ether 8 with a wide range of acetals in the presence of tin tetrachloride led to a the diastereoselective construction of the C-9 quaternary center of 33 new building blocks derived from the Wieland-Miescher ketone derivative 3.
- Schiavo, Lucie,Lebedel, Ludivine,Massé, Paul,Choppin, Sabine,Hanquet, Gilles
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p. 6247 - 6258
(2018/06/22)
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- Silver-Catalyzed Olefination of Acetals and Ketals with Diazoesters to β-Alkoxyacrylates
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The first silver-catalyzed reaction of acetals or ketals with diazoesters leading to trisubstituted or tetrasubstituted β-alkoxyacrylates is now reported. A broad range of acetals and ketals bearing different substituents is compatible with this protocol and thus provides an attractive approach for the synthesis of complex β-alkoxyacrylates. The power of this method was further demonstrated by the successful synthesis of picoxystrobin, which is one of the most popular agricultural fungicides commercialized by Dupont.
- Li, Jiawen,Qian, Bo,Huang, Hanmin
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supporting information
p. 7090 - 7094
(2018/11/23)
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- House bulb light-induced photochemical acetalization of carbonyl compounds catalyzed by Eosin Y
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We have systematically studied the reactions of acetalization and found that high reaction efficiency can be achieved using cheap and readily available organic Eosin Y as catalyst. The reaction proceeds smoothly under house bulbs and shows excellent functional group tolerance. The substrates of the reaction system are compatible with aromatic aldehydes, aliphatic aldehydes, aromatic ketones, and cyclic ketones with high yields.
- Zhou, Quan,Jia, Tao,Li, Xiao-Xuan,Zhou, Lin,Li, Chang-Jiang,Feng, Yi-Si
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supporting information
p. 1068 - 1075
(2018/05/23)
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- Ru(II)-functionalized SBA-15 as highly chemoselective, acid free and sustainable heterogeneous catalyst for acetalization of aldehydes and ketones
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Combining electron deficient Ru(II) coordination sites with organofunctionalized SBA-15, (L)Ru(II)@SBA-15, result in a mild, neutral, water scavenger free and chemo-selective acetalization catalyst for cyclic/acyclic acetals. Vacant coordination sites of ruthenium in (L)Ru(II)@SBA-15 activates protecting groups as well as reactants simultaneously and restricts the reverse acetalization reaction. Synthesized (L)Ru(II)@SBA-15 catalyst has been thoroughly characterized and act as competitive catalyst compared to conventional acid catalysts. (L)Ru(II)@SBA-15 performs high catalytic activity as well as selectivity within 20 min with high TOF. The catalyst can be recycled and reaction parameters are optimized.
- Lazar, Anish,Betsy,Vinod,Singh
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- Hydrothermal synthesis of chiral inorganic-organic CoII complex: Structural, thermal and catalytic evaluation
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By heating the cobalt chloride hexahydrate (CoCl2·6H2O) with the R form of the organic amine α-methylbenzylamine (C8H11N) under hydro(solvo)thermal conditions, we have successfully generated the corresponding non-centrosymmetric homochiral hybrid tris (α-methylbenzylammonium tetrachloridocobaltate chloride [R-(C8H12N)3][CoCl4]Cl abbreviated R(MBA)Co. We present the growth conditions together with a characterization of the single crystals by means of X-ray single-crystal diffraction, Fourier-transform infrared, TG/TDA thermal decomposition and catalytic properties. This inorganic–organic hybrid compound crystallizes in the chiral space group P21 and exhibits a supramolecular-layered organization wherein a double layer of (R)-methylbenzylammonium cations and the uncoordinated chloride anions are sandwiched between anionic layers, formed by isolated tetrachloridocobaltate tetrahedra. The crystal packing is governed by a three-dimensional network of N/C–H?Cl hydrogen bonds between the inorganic and organic moieties and C–H···π interactions between the aromatic rings of the organic moieties themselves. Thermal analysis discloses a phase transition at the temperature 130 °C. The Co complex was also employed as suitable catalyst activating the acetal formation reaction of aldehydes using MeOH as solvent and as the unique source of acetalization.
- Salah, Assila Maatar Ben,Herrera, Raquel P.,Na?li, Houcine
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p. 356 - 362
(2018/05/29)
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- Tropylium salts as efficient organic Lewis acid catalysts for acetalization and transacetalization reactions in batch and flow
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Acetalization reactions play significant roles in the synthetically important masking chemistry of carbonyl compounds. Herein we demonstrate for the first time that tropylium salts can act as organic Lewis acid catalysts to facilitate acetalization and transacetalization reactions of a wide range of aldehyde substrates. This metal-free method works efficiently in both batch and flow conditions, prompting further future applications of tropylium organocatalysts in green synthesis.
- Lyons,Crocker,Enders,Nguyen
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supporting information
p. 3993 - 3996
(2017/09/08)
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- Visible-light-induced acetalization of aldehydes with alcohols
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In this work, we have achieved a simple and general method for acetalization of aldehydes by means of a photochemical reaction under low-energy visible light irradiation. A broad range of aromatic, heteroaromatic, and aliphatic aldehydes have been protected under neutral conditions in good to excellent yields using a catalytic amount of Eosin Y as the photocatalyst. Our visible light mediated acetalization strategies are successful for more challenging acid-sensitive aldehydes and sterically hindered aldehydes. Notably, this protocol is chemoselective to aldehydes, while ketones remain intact.
- Yi, Hong,Niu, Linbin,Wang, Shengchun,Liu, Tianyi,Singh, Atul K.,Lei, Aiwen
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supporting information
p. 122 - 125
(2017/11/27)
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- Phosphorylated Polyacrylonitrile Fibers as an Efficient and Greener Acetalization Catalyst
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A novel solid acid catalyst (PANEAPF) is developed by immobilization of phosphoric acid on polyacrylonitrile fiber through covalent bonding. Various characterization techniques such as elemental analysis (EA), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), etc. are utilized to confirm the successful grafting and the stability of the fiber catalysts during application. PANEAPF shows high catalytic activity in the acetalization of aldehydes owing to the high utilization efficiency of its functionalized acid sites. In addition, the strong polarity micro-environment in the surface layers of PANEAPF make it highly suitable for catalytic application in both water and alcohol. Furthermore, the fiber catalyst can be applied to the acetalization of aldehydes in a continuous-flow process at room temperature, and shows excellent reactivity and superior recyclability (over 20 times). The many advantages of PANEAPF such as simple preparation, convenient regulation of acid amount, high durability, and eco-friendly process make it very attractive for fixed-bed reactors in the chemical industry.
- Xu, Gang,Cao, Jian,Zhao, Yali,Zheng, Lishuo,Tao, Minli,Zhang, Wenqin
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supporting information
p. 2565 - 2575
(2017/09/25)
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- A visible-light-induced chemoselective radical/oxidative addition domino process to access α-chloro and α-alkoxy aryl ketones
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A visible-light-induced radical-triggered chemoselective domino process to access α,α-di-functionalized ketones under mild conditions has been developed. This protocol provides a direct approach to synthesize α-chloro or α-alkoxy aryl ketones based on the electronic properties of the substrates. The reaction can tolerate a variety of functional groups to afford the corresponding products in moderate to good yields.
- Niu, Teng-Fei,Jiang, Ding-Yun,Li, Si-Yuan,Ni, Bang-Qing,Wang, Liang
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p. 13105 - 13108
(2016/11/09)
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- Regioselective Allylation of Carbon Electrophiles with Alkenyl-silanes under Dual Catalysis by Cationic Platinum(II) Species
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In the presence of catalytic amounts of platinum(II) chloride and silver(I) hexafluoroantimonate, (Z)-alkenylsilanes reacted with various carbon electrophiles (acetals, aminals, carboxylic anhydrides, alkyl chlorides, etc.) at the γ-position to give allylation products. A plausible mechanism for the platinum-catalyzed allylation involves alkene migration of alkenylsilanes to allylsilanes and subsequent allylation of carbon electrophiles, both of which are catalyzed by a cationic platinum(II) species.
- Kinoshita, Hidenori,Kizu, Ryosuke,Horikoshi, Masahiro,Inoue, Gen,Fujimoto, Masayuki,Saito, Masanori,Ichikawa, Junji,Hosomi, Akira,Miura, Katsukiyo
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supporting information
p. 520 - 534
(2016/02/16)
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- Graphitic carbon nitride catalysed photoacetalization of aldehydes/ketones under ambient conditions
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Graphitic-C3N4 is shown for the first time to catalyse photoacetalization of aldehydes/ketones with alcohols to acetals in high yields using visible light under ambient conditions; transient charge separation over the material is effective to catalyse the reaction in the absence of Lewis or Br?nsted acids, giving a new green alternative catalyst.
- Abdullah Khan,Teixeira, Ivo F.,Li, Molly M. J.,Koito, Yusuke,Tsang, Shik Chi Edman
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supporting information
p. 2772 - 2775
(2016/02/18)
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- Crystallisation, thermal analysis and acetal protection activity of new layered Zn(II) hybrid polymorphs
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Two new polymorphic mononuclear complexes, with analogous structural formula (C6H9N2)2[Zn(H2O)6](SO4)2·2H2O, of zinc(ii) templated by 2-amino-6-methylpyridinium ligand have been discovered. These polymorphic hybrid crystals, which differ only in terms of their crystal structures, were prepared in one-step synthesis under ambient conditions and investigated for their thermal and catalytic properties. Single-crystal X-ray diffraction of the obtained materials revealed that polymorphs 1 and 2 crystallise in the triclinic system, space group P1. In an effort to further explore the form diversity of these compounds, the structural arrangements and intermolecular interactions such as hydrogen-bonding and π?π interactions are discussed from which supramolecular assembly was formed. Meanwhile, these new polymorphic forms can be described as the stacking of 3D layers where the interlayer distances are 13.23 and 12.59 ? for 1 and 2, respectively. The thermal behaviour of the precursors checked by TG-DTA analysis for both zinc sulfate polymorphs and variable temperature powder X-ray diffraction (VT-PXRD) show successive intermediate crystalline anhydrous phases upon dehydration in 1. The catalytic activity of both polymorphic structures has been tested in the acetalisation reaction of aldehydes as a benchmark process. Interestingly, both complexes showed excellent activity with almost total conversion in many examples and using MeOH as solvent and as the unique source of acetalisation.
- Sa?d, Salem,Na?li, Houcine,Bataille, Thierry,Herrera, Raquel P.
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p. 5365 - 5374
(2016/07/21)
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- Platinum-catalyzed allylation of carbon electrophiles with alkenylsilanes
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In the presence of catalytic amounts of PtCl2 and AgSbF6, (Z)-alkenylsilanes react with various carbon electrophiles at the γ-position to give allylation products. A plausible mechanism for the Pt-catalyzed allylation involves alkene migration of alkenylsilanes to allylsilanes and subsequent allylation of carbon electrophiles.
- Kinoshita, Hidenori,Kizu, Ryosuke,Inoue, Gen,Fujimoto, Masayuki,Saito, Masanori,Ichikawa, Junji,Hosomi, Akira,Miura, Katsukiyo
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supporting information
p. 713 - 716
(2015/01/30)
-
- A General Access to Propargylic Ethers through Br?nsted Acid Catalyzed Alkynylation of Acetals and Ketals with Trifluoroborates
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A general Br?nsted acid catalyzed methodology for the alkynylation of acetals and ketals with alkynyltrifluoroborate salts has been developed. The reaction proceeds rapidly to afford valuable synthetic building block propargylic ethers in good to excellent yields. Unlike Lewis acid catalyzed transformations of trifluoroborates, this approach does not proceed via unstable organodifluoroborane intermediate. As a result, the developed methodology features excellent functional group tolerance and good atom economy. Br?nsted acid catalyzed alkynylation of acetals and ketals is described. Alkynyltrifluoroborate salts react rapidly to afford propargylic ethers. Organodifluoroborane, which is a common intermediate in Lewis acid catalyzed reactions of trifluoroborates, has not been observed. The reaction exhibits generally high yields and excellent functional group tolerance.
- Baxter, Matthew,Bolshan, Yuri
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supporting information
p. 13535 - 13538
(2015/09/22)
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- Zeolite nanofiber assemblies as acid catalysts with high activity for the acetalization of carbonyl compounds with alcohols
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Zeolite nanofiber assemblies (HNB-MOR) as efficient heterogeneous catalysts for the formation of a range of acetals in good yields. The mesoporosity of HNB-MOR benefits mass transfer, and the strong acidic sites on HNB-MOR facilitate acetalization activity. The catalyst can be reused 10 times without loss of activity.
- Liu, Taotao,Fu, Wenqian,Zheng, Xiang,Jiang, Jun,Hu, Maolin,Tang, Tiandi
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p. 18217 - 18221
(2014/05/20)
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- Stepwise construction of discrete heterometallic coordination cages based on self-sorting strategy
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A chelation-directed self-sorting synthesis of a series of cationic heterometallic coordination cages (HCCs) with tunable sizes is described. Two complexation modes were found in the cage-forming process. Metal-anchoring host-guest behavior and size-selective in-cage catalytic activities were found for the HCCs.
- Li, Hao,Han, Ying-Feng,Lin, Yue-Jian,Guo, Zi-Wei,Jin, Guo-Xin
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supporting information
p. 2982 - 2985
(2014/03/21)
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- Role of the 4,6-O-acetal in the regio-and stereoselective conversion of 2,3-di-O-sulfonyl-b-D-galactopyranosides to D-idopyranosides
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The recently reported conversion of 2,3-di-O-sulfonyl-D-galactopyranosides to D-idopyranosides has provided an efficient route to obtaining orthogonally-protected idopyranoside building blocks with a b-1,2-cis glycosidic linkage. In an effort to expand th
- Hevey, Rachel,Chen, Xining,Ling, Chang-Chun
-
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- A Paal-Knorr approach to 3,4-diaryl-substituted pyrroles: Facile synthesis of lamellarins O and Q
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A very simple, yet efficient synthetic methodology, to obtain 3,4-diaryl-substituted pyrroles is described. The approach is based on the Knoevenagel condensation between arylacetonitriles and substituted aromatic aldehydes, followed by conjugate addition of cyanide to afford succinonitriles in excellent yields. The products thus obtained were subjected to DIBAL-H reduction, followed by cyclization under acidic conditions to produce the corresponding pyrroles in good overall yields. The utility of this protocol is exemplified by the synthesis of the marine alkaloids lamellarins O and Q.
- Ramirez-Rodriguez, Armando,Mendez, Jose M.,Jimenez, Cristina C.,Leon, Fernando,Vazquez, Alfredo
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p. 3321 - 3326,6
(2012/12/12)
-
- 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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- Indium(III) triflate catalysed transacetalisation reactions of diols and triols under solvent-free conditions
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Acyclic acetals and ketals undergo transacetalisation in the presence of catalytic quantities of indium(III) triflate (In(OTf)3) and diols or triols under solvent-free conditions to generate the corresponding cyclic acetals and ketals in excellent yield. The methodology has been further developed to encompass a tandem acetalisation-acetal exchange protocol, which provides a facile and high yielding route to cyclic ketals from unreactive ketones under very mild reaction conditions.
- Smith, Brendan M.,Kubczyk, Tomasz M.,Graham, Andrew E.
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supporting information; experimental part
p. 7775 - 7781
(2012/09/21)
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- Highly efficient and chemoselective acetalization and thioacetalization of aldehydes catalyzed by propylphosphonic anhydride (T3P) at room temperature
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Propylphosphonic anhydride (T3P), a low toxic peptide coupling agent, has been demonstrated to be an efficient catalyst for the chemoselective acetalization and thioacetalization of aldehydes in the presence of ketones. Cyclic and acyclic acetals of diverse aldehydes were obtained in good to excellent yields at room temperature in the presence of a catalytic amount of T3P.
- Augustine, John Kallikat,Bombrun, Agnes,Sauer, Wolfgang H.B.,Vijaykumar, Pujari
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p. 5030 - 5033
(2012/11/07)
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- Efficient and chemoselective acetalization and thioacetalization of carbonyls and subsequent deprotection using InF3 as a reusable catalyst
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An efficient and chemoselective method for preparation of acetals and dithioacetals of aldehydes and their deprotection under catalysis of InF 3 is described.
- Madabhushi, Sridhar,Mallu, Kishore Kumar Reddy,Chinthala, Narsaiah,Beeram, China Ramanaiah,Vangipuram, Venkata Sairam
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experimental part
p. 697 - 701
(2012/02/15)
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- Mesoporous aluminosilicate-catalyzed allylation of carbonyl compounds and acetals
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A mesoporous aluminosilicate (Al-MCM-41) was found to be an effective heterogeneous catalyst for the reaction of both carbonyl compounds and acetals with allylsilanes to afford the corresponding homoallyl silyl ethers and homoallyl alkyl ethers, respectively. Both the mesoporous structure and the presence of aluminum moiety were indispensable for the high catalytic activity of Al-MCM-41. Moreover, Al-MCM-41 could catalyze the reaction of acetals chemoselectively in the presence of the corresponding carbonyl compounds. The solid acid catalyst Al-MCM-41 could be recovered easily by filtration and could be reused three times without a significant loss of catalytic activity.
- Ito, Suguru,Hayashi, Akira,Komai, Hirotomo,Yamaguchi, Hitoshi,Kubota, Yoshihiro,Asami, Masatoshi
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supporting information; experimental part
p. 2081 - 2089
(2011/04/19)
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- Nanoporous aluminosilicate catalyzed Friedel-Crafts alkylation reactions of indoles with aldehydes and acetals
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Nanoporous aluminosilicate materials efficiently catalyze Friedel-Crafts reactions of indoles to produce bisindolylalkane products. These reactions proceed rapidly and in high yields when acetals are used in place of the more commonly used carbonyl reagents. It is possible to capitalise on the large difference in the rates of reaction observed with aldehydes and acetals to develop a tandem acetalization-Friedel-Crafts protocol in which the acetal is generated in situ and undergoes subsequent reaction.
- Kubczyk, Tomasz M.,Williams, Sarah M.,Kean, Jacqueline R.,Davies, Thomas E.,Taylor, Stuart H.,Graham, Andrew E.
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supporting information; experimental part
p. 2320 - 2325
(2011/10/09)
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- Catalytic synthesis of γ-alkoxy-α-keto esters
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Copper(II) triflate effectively catalyzes the reaction of (trimethylsilyloxy)acrylic esters and acetals to form -alkoxy - keto esters. The reaction proceeds under mild conditions providing products in good to excellent yields. The substrate scope was investigated, and it was demonstrated that the products could be converted into related compounds such as γ-hydroxy -α- keto esters and α-oximes. Georg Thieme Verlag Stuttgart - New York.
- Krebs, Anke,Bolm, Carsten
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supporting information; experimental part
p. 671 - 673
(2011/05/16)
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- Mesoporous sulfated zirconia mediated acetalization reactions
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A novel, convenient, one step synthetic procedure for the synthesis of mesoporous sulfated zirconia (m-SZ) using zirconium carbonate complex and its use as solid acid catalyst for the acetalization of different carbonyl compound is reported. The high specific BET surface area (234 m2 g -1) of m-SZ is achieved after the removal of the surfactant (cetyltrymethylammonium bromide, CTAB) through calcination at 550 °C for 6 h. Microscopic analysis indicated the presence of spherical particles with worm like pores. DRIFT (diffuse reflectance FTIR) of pyridine adsorbed m-SZ and NH3-TPD (temperature programmed desorption) analysis suggested the presence of appreciable amount of Bro?nsted acid sites. The synthesized m-SZ showed high catalytic activity towards protection of carbonyl compounds through acetal/ketal formation. For the open ketal (from cyclohexanone and methanol) 97% conversion with 100% selectivity was obtained in 1 h at room temperature under solvent free condition. The catalyst can be easily recycled after separation from the reaction system without considerable loss in catalytic activity.
- Sinhamahapatra, Apurba,Sutradhar, Narottom,Ghosh, Malay,Bajaj, Hari C.,Panda, Asit B.
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experimental part
p. 87 - 93
(2012/04/10)
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- ZWITTERIONIC PHOSPHONIUM SALTS
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A zwitterionic phosphonium salt of Formula I: wherein n is 0 or 1; R is H or SO3-; R' is selected from the group consisting of C1-C10 alkyl, C2-C10 alkenyl, C2-C10 alkynyl, C3-C10 cycloalkyl, phenyl, substituted phenyl, benzyl and C1-C10 alkoxycarbonyl; R' is CX3 when n is O; and X is selected from the group consisting of F, Cl, Br and I. The zwitterionic phosphonium salts are useful reagents for the preparation of alkenes and acetals from the corresponding aldehyde.
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Page/Page column 30
(2010/04/03)
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- Cobalt(II) schiff base functionalized mesoporous silica as an efficient and recyclable chemoselective acetalization catalyst
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Cobalt(II) Schiff base functionalized mesoporous silica was synthesized from covalent attachment via the introduction of Co(OAc)2 to salicylaldimine functionalized mesoporous silica. The catalyst proved to be chemoselective one for the acetalization of aldehydes to the corresponding acetals in alcohol. The immobilized catalyst can be easily recovered and reused for at least ten reaction cycles without significant loss of its catalytic activity.
- Rajabi
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scheme or table
p. 695 - 701
(2010/11/16)
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- Single-step conversion of electron-deficient aldehydes into the corresponding esters in aqueous alcohols in the presence of iodine and sodium nitrite
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The direct conversion of aldehydes into their corresponding esters in the presence of iodine and sodium nitrite in aqueous alcohols is reported. In all these reactions, alcohol serves as reactant and also as reaction medium. Almost quantitative yields were obtained with aldehydes containing electron-withdrawing substituents and heterocyclic aldehydes. Georg Thieme Verlag Stuttgart.
- Kiran,Ikeda, Reiko,Sakai, Norio,Konakahara, Takeo
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experimental part
p. 276 - 282
(2010/03/26)
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- Chemoselective protection of aldehydes in the presence of ketones using rupvp complex as a heterogeneous catalyst
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Ruthenium(III)-polyvinyl pyridine (RuPVP) complex was prepared by refluxing a methanolic solution of polyvinyl pyridine and trihydrated ruthenium trichloride. RuPVP catalyst was characterized by Fourier transform-infrared and diffential scanning calorimetry-thermogravimetry (TG). The catalyst was used for chemoselective protection of aldehydes in the presence of a ketonic carbonyl group.
- Kshirsagar, Siddheshwar W.,Patil, Nitin R.,Samant, Shriniwas D.
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experimental part
p. 407 - 413
(2010/04/04)
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- N-PHENYL-DIOXO-HYDROPYRIMIDINES USEFUL AS HEPATITIS C VIRUS (HCV) INHIBITORS
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This invention relates to: (a) compounds and salts thereof that, inter alia, inhibit HCV; (b) intermediates useful for the preparation of such compounds and salts; (c) compositions comprising such compounds and salts; (d) methods for preparing such interm
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Page/Page column 114
(2009/04/25)
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- Zinc chloride as an efficient catalyst for chemoselective dimethyl acetalization
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Commercially available anhydrous zinc chloride has been found to be a highly efficient catalyst for dimethyl acetalization in high yields by treatment of aldehydes and ketones with trimethyl orthoformate in methanol-cyclohexane at reflux temperature. Copyright Taylor & Francis Group, LLC.
- Roy, Anupam,Rahman, Matiur,Das, Sudarshan,Kundu, Dhiman,Kundu, Shrishnu Kumar,Majee, Adinath,Hajra, Alakananda
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experimental part
p. 590 - 595
(2009/07/04)
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- Carbon tetrabromide/sodium triphenylphosphine-m-sulfonate (TPPMS) as an efficient and easily recoverable catalyst for acetalization and tetrahydropyranylation reactions
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A solid complex, conveniently prepared from carbon tetrabromide and sodium triphenylphos-phine-m-sulfonate (TPPMS), can be used as an easily recoverable catalyst for the selective acetalization of aldehydes and tetrahydropyranylation of alcohols. The catalyst can be recovered by simple pre-cipitation with ether and can be reused at least 7 times without loss of catalytic activity.
- Huo, Congde,Chan, Tak Hang
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experimental part
p. 1933 - 1938
(2011/02/28)
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- DNA-targeting pyrroloquinoline-linked butenone and chalcones: Synthesis and biological evaluation
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A series of conjugates of α,β-unsaturated ketone systems, phenyl-butenone and diaryl-propenones (chalcones), with the tricyclic planar pyrroloquinoline nucleus were synthesised and evaluated for their anticancer properties. The aim was to target DNA by bu
- Via, Lisa Dalla,Gia, Ornella,Chiarelotto, Gianfranco,Ferlin, Maria Grazia
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experimental part
p. 2854 - 2861
(2009/10/10)
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- Reductive openings of acetals: Explanation of regioselectivity in borane reductions by mechanistic studies
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(Graph Presented) The mechanisms of regioselective reductive openings of acetals were investigated in several model systems by a combination of Hammett plots, kinetic experiments, density functional calculations, and 11B NMR. The regioselectivity of borane reductions of cyclic acetals can be controlled by the choice of borane. Lewis acid activation of BH3·NMe 3 increases the reaction rate and renders the borane the most electrophilic species, which associates to the more electron-rich oxygen of the acetal. In contrary, without activation, the regioselectivity is instead directed by the Lewis acid, as exemplified by the reaction with BH 3·THF.
- Johnsson, Richard,Olsson, Dan,Ellervik, Ulf
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p. 5226 - 5232
(2008/12/21)
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