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Search for "acid catalyst" in Full Text gives 124 result(s) in Beilstein Journal of Organic Chemistry.

Novel approach to hydroxy-group-containing porous organic polymers from bisphenol A

  • Tao Wang,
  • Yan-Chao Zhao,
  • Li-Min Zhang,
  • Yi Cui,
  • Chang-Shan Zhang and
  • Bao-Hang Han

Beilstein J. Org. Chem. 2017, 13, 2131–2137, doi:10.3762/bjoc.13.211

Graphical Abstract
  • the stretching vibration of methyl groups shows quantitative changes between BPA and PPOPs, suggesting the degradation of BPA in o-dichlorobenzene and it is reported that the cleavage of methylene can be catalyzed under acidic or basic conditions [29][30]. p-Toluenesulfonic acid acted as an acid
  • catalyst in this contribution and will promote the cleavage of BPA at high temperature. The broad absorption bands located at ca. 3500 cm−1 is attributed to the characteristic stretching vibration of hydroxy groups, which is consistent with the literature data [25]. The absorption peak at 1705 cm−1
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Published 12 Oct 2017

New bio-nanocomposites based on iron oxides and polysaccharides applied to oxidation and alkylation reactions

  • Daily Rodríguez-Padrón,
  • Alina M. Balu,
  • Antonio A. Romero and
  • Rafael Luque

Beilstein J. Org. Chem. 2017, 13, 1982–1993, doi:10.3762/bjoc.13.194

Graphical Abstract
  • . The quantity of probe molecule adsorbed by the solid acid catalyst can subsequently be easily quantified. In order to distinguish between Lewis and Brønsted acidity, it was assumed that all DMPY selectively titrates Brønsted sites (methyl groups hinder coordination of nitrogen atoms with Lewis acid
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Published 21 Sep 2017

New tricks of well-known aminoazoles in isocyanide-based multicomponent reactions and antibacterial activity of the compounds synthesized

  • Maryna V. Murlykina,
  • Maryna N. Kornet,
  • Sergey M. Desenko,
  • Svetlana V. Shishkina,
  • Oleg V. Shishkin,
  • Aleksander A. Brazhko,
  • Vladimir I. Musatov,
  • Erik V. Van der Eycken and
  • Valentin A. Chebanov

Beilstein J. Org. Chem. 2017, 13, 1050–1063, doi:10.3762/bjoc.13.104

Graphical Abstract
  • -binucleophile, acidcatalyst). Literature data indicate [14][25][59][97][98][99][100][101] that 5-aminopyrazoles bearing in the fourth position electron-withdrawing substituents like carboxamide, carboxylate or a carbonitrile group, posses chemical properties being different from other 5-aminopyrazoles but
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Published 31 May 2017

cis-Diastereoselective synthesis of chroman-fused tetralins as B-ring-modified analogues of brazilin

  • Dimpee Gogoi,
  • Runjun Devi,
  • Pallab Pahari,
  • Bipul Sarma and
  • Sajal Kumar Das

Beilstein J. Org. Chem. 2016, 12, 2816–2822, doi:10.3762/bjoc.12.280

Graphical Abstract
  • Friedel–Crafts cyclization (Scheme 2, upper panel) and the products are relevant in the field of natural product-like molecules, because the synthesized molecules are close analogs of a natural product (brazilin). Moreover, the use of TsOH·H2O as an easily-accesible Brønsted acid catalyst with low loading
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Published 21 Dec 2016

The digital code driven autonomous synthesis of ibuprofen automated in a 3D-printer-based robot

  • Philip J. Kitson,
  • Stefan Glatzel and
  • Leroy Cronin

Beilstein J. Org. Chem. 2016, 12, 2776–2783, doi:10.3762/bjoc.12.276

Graphical Abstract
  • (triflic) acid (CF3SO3H) as the Lewis acid catalyst to yield 4-isobutylpropiophenone (2). Once this is complete a solution of di(acetoxy)phenyl iodide (PhI(OAc)2) and trimethyl orthoformate (TMOF) in methanol (MeOH) is added to the reaction mixture in order to induce a 1,2-aryl migration to produce the
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Published 19 Dec 2016

Selective synthesis of thioethers in the presence of a transition-metal-free solid Lewis acid

  • Federica Santoro,
  • Matteo Mariani,
  • Federica Zaccheria,
  • Rinaldo Psaro and
  • Nicoletta Ravasio

Beilstein J. Org. Chem. 2016, 12, 2627–2635, doi:10.3762/bjoc.12.259

Graphical Abstract
  • the green chemistry point of view would be the direct substitution of alcohols (that are also available at low cost) with thiols. In this case the only byproduct will be water. However, due to the lack of a good leaving group the use of an acid catalyst is mandatory. Both Brønsted and Lewis acids can
  • of thioethers 3a–p synthesized. Product distribution during reaction of 5b and 2a over a solid acid catalyst. Product distribution during reaction of 1c and 2e. Recyclability test of SiAl 0.6 catalyst in the reaction of 1a and 2a. Racemization of (R)-1-phenylethanol during the reaction with
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Published 06 Dec 2016

Diels–Alder reactions in confined spaces: the influence of catalyst structure and the nature of active sites for the retro-Diels–Alder reaction

  • Ángel Cantín,
  • M. Victoria Gomez and
  • Antonio de la Hoz

Beilstein J. Org. Chem. 2016, 12, 2181–2188, doi:10.3762/bjoc.12.208

Graphical Abstract
  • ] (see Figure 2a, b) that owing to the retro-DA reaction the selectivity of the endo-endo isomer decreases from 85% to 65% as we previously reported. [30] Considering the interesting application of beta zeolites as Lewis acid catalyst for Diels–Alder reactions in different fields, i.e., the formation of
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Published 13 Oct 2016

Silica-supported sulfonic acids as recyclable catalyst for esterification of levulinic acid with stoichiometric amounts of alcohols

  • Raimondo Maggi,
  • N. Raveendran Shiju,
  • Veronica Santacroce,
  • Giovanni Maestri,
  • Franca Bigi and
  • Gadi Rothenberg

Beilstein J. Org. Chem. 2016, 12, 2173–2180, doi:10.3762/bjoc.12.207

Graphical Abstract
  • chromatography on silica gel (eluent = hexane/ethyl acetate) and characterised by multinuclear NMR. Anchoring methodologies: a) impregnation; b) covalent binding. Activity of the supported sulfonic acid catalyst within the first six cycles. Reaction conditions: 1 mol % cat., acid:alcohol ratio = 1:1, solvent
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Published 12 Oct 2016

Solvent-free synthesis of novel para-menthane-3,8-diol ester derivatives from citronellal using a polymer-supported scandium triflate catalyst

  • Lubabalo Mafu,
  • Ben Zeelie and
  • Paul Watts

Beilstein J. Org. Chem. 2016, 12, 2046–2054, doi:10.3762/bjoc.12.193

Graphical Abstract
  • variety of applications. The synthesis method involves the acylation of 3 with various acid anhydrides. The synthesis method also employs a polymer-supported scandium triflate as a water resistant and environmentally friendly acid catalyst. Results and Discussion Synthesis para-menthane-3,8-diol from
  • (140 g, 0.0076 mol of a 0.3% (v/v)) solution at a temperature of 100 °C. After 4 hour of stirring the aqueous phase was separated from the organic oil phase. The organic phase was neutralised with 50 mL of 2.5% (v/v) sodium hydrogen carbonate (NaHCO3) solution to remove the remains of sulphuric acid
  • catalyst and dried (MgSO4). The product was recrystallized from n-hexane at −18 °C for 24 hours. p-Menthane-3,8-diol (3) was obtained as white crystals (96%). 1H NMR (400 MHz, CDCl3, ppm) δ 0.80–0.96 (m, 3H), 0.89–0.90 (m, 1H), 0.99–1.03 (m, 2H), 1.11–1.19 (m, 3H), 1.33 (s, 3H), 1.66–1.68 (m, 2H), 1.72
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Published 19 Sep 2016

Rearrangements of organic peroxides and related processes

  • Ivan A. Yaremenko,
  • Vera A. Vil’,
  • Dmitry V. Demchuk and
  • Alexander O. Terent’ev

Beilstein J. Org. Chem. 2016, 12, 1647–1748, doi:10.3762/bjoc.12.162

Graphical Abstract
  • , the mechanism of this reaction is still not fully understood. The nature of the acid catalyst [220] and the type of O–O-bond cleavage in the Criegee intermediate [221] were found to play an important role in this reaction. Probably the hydrogen bonds in Baeyer–Villiger reactions play an important role
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Published 03 Aug 2016

Rh-Catalyzed reductive Mannich-type reaction and its application towards the synthesis of (±)-ezetimibe

  • Motoyuki Isoda,
  • Kazuyuki Sato,
  • Yurika Kunugi,
  • Satsuki Tokonishi,
  • Atsushi Tarui,
  • Masaaki Omote,
  • Hideki Minami and
  • Akira Ando

Beilstein J. Org. Chem. 2016, 12, 1608–1615, doi:10.3762/bjoc.12.157

Graphical Abstract
  • asymmetric Mannich reaction using a Lewis acid catalyst [1]. (L)-Proline is known as an excellent promoter for the Mannich reaction [2][3][4][5][6], and besides this, the reaction of the silyl enol ether derivatives with imines was used as an effective method [7][8][9]. In this situation, a wide variety of
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Published 27 Jul 2016

The hydrolysis of geminal ethers: a kinetic appraisal of orthoesters and ketals

  • Sonia L. Repetto,
  • James F. Costello,
  • Craig P. Butts,
  • Joseph K. W. Lam and
  • Norman M. Ratcliffe

Beilstein J. Org. Chem. 2016, 12, 1467–1475, doi:10.3762/bjoc.12.143

Graphical Abstract
  • catalyst concentration, i.e., kobs = kH+ [H+]. Nevertheless, we have used the same acid catalyst concentration ([H+] = 2 × 10−4 M) as previous workers [18] except in the case of particularly slow reactions where [H+] was increased to 5 × 10−4 M to ensure completion within a reasonable time. Acyclic
  • . Adjustments to the acid catalyst concentration were made on an iterative basis in order to ensure the kinetic runs were complete within reasonable time-scales. Freshly distilled 2 (33 µL, 0.3 mmol) and 6 (38 µL, 0.3 mmol) were added to anhydrous CD3CN (1200 µL), and the resulting solution was divided equally
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Published 15 Jul 2016

Cupreines and cupreidines: an established class of bifunctional cinchona organocatalysts

  • Laura A. Bryant,
  • Rossana Fanelli and
  • Alexander J. A. Cobb

Beilstein J. Org. Chem. 2016, 12, 429–443, doi:10.3762/bjoc.12.46

Graphical Abstract
  • the flexible cinchona framework, which has a knock-on effect on the catalytic outcome. Interestingly, the chiral nature of the binol phosphoric acid catalyst (S)-49 in the anti-selective process was not thought to be hugely influential upon the stereochemical outcome. Indeed replacing it with diphenyl
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Published 07 Mar 2016

Self and directed assembly: people and molecules

  • Tony D. James

Beilstein J. Org. Chem. 2016, 12, 391–405, doi:10.3762/bjoc.12.42

Graphical Abstract
  • using boron as a chiral catalyst was a good idea. We quickly came up with a research plan over a beer or two (Figure 13). Then on our return to the UK we quickly put these ideas into practice with the investigation of a “chiral boron reagent” formed between binol and trimethoxy borate for the Lewis acid
  • catalyst of diastereoselective aza-Diels–Alder reactions [68] (Figure 14). While, the structure of the “chiral boron reagent” still remains unknown during our investigation of analogues we discovered a very interesting three-component self-assembly. Chiral binol, a chiral amine and 2-formylbenzeneboronic
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Published 01 Mar 2016

Latent ruthenium–indenylidene catalysts bearing a N-heterocyclic carbene and a bidentate picolinate ligand

  • Thibault E. Schmid,
  • Florian Modicom,
  • Adrien Dumas,
  • Etienne Borré,
  • Loic Toupet,
  • Olivier Baslé and
  • Marc Mauduit

Beilstein J. Org. Chem. 2015, 11, 1541–1546, doi:10.3762/bjoc.11.169

Graphical Abstract
  • /catalyst ratios were investigated, and 150 equiv of TFA afforded the best catalytic performance in terms of initiation rate and conversion. In fact, both a decrease (100 equiv) and an increase (200 equiv) of this acid/catalyst ratio led to a significant deterioration of the kinetic profile. Subsequently
  • handle and to operate (Figure 2). Consistent with its stability in solution, the latent catalyst 4a appeared totally inactive at room temperature (<1% conversion after 24 h at 297 K), while catalytic activity was observed in the RCM of diethyl diallylmalonate (DEDAM) after addition of TFA. Several acid
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Published 03 Sep 2015

The synthesis of active pharmaceutical ingredients (APIs) using continuous flow chemistry

  • Marcus Baumann and
  • Ian R. Baxendale

Beilstein J. Org. Chem. 2015, 11, 1194–1219, doi:10.3762/bjoc.11.134

Graphical Abstract
  • order to avoid downstream incompatibilities. The initial step was a Friedel–Crafts acylation of isobutylbenzene (10) with propionic acid (11) in the presence of excess triflic acid (12). The transformation was found to work very effectively and the acid catalyst was also tolerated in the subsequent 1,2
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Published 17 Jul 2015

Properties of PTFE tape as a semipermeable membrane in fluorous reactions

  • Brendon A. Parsons,
  • Olivia Lin Smith,
  • Myeong Chae and
  • Veljko Dragojlovic

Beilstein J. Org. Chem. 2015, 11, 980–993, doi:10.3762/bjoc.11.110

Graphical Abstract
  • hypothesis, we carried out a reaction of bromine with benzene. In the absence of a catalyst there is only a very slow reaction. However, in the presence of a Lewis acid catalyst there is a fast bromination reaction. Since iron reacts with bromine to produce iron(III) bromide, a stirring bar may conceivably
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Published 09 Jun 2015

The unexpected influence of aryl substituents in N-aryl-3-oxobutanamides on the behavior of their multicomponent reactions with 5-amino-3-methylisoxazole and salicylaldehyde

  • Volodymyr V. Tkachenko,
  • Elena A. Muravyova,
  • Sergey M. Desenko,
  • Oleg V. Shishkin,
  • Svetlana V. Shishkina,
  • Dmytro O. Sysoiev,
  • Thomas J. J. Müller and
  • Valentin A. Chebanov

Beilstein J. Org. Chem. 2014, 10, 3019–3030, doi:10.3762/bjoc.10.320

Graphical Abstract
  • of 8 and 3a under ultrasonication at room temperature gave the corresponding final product essentially after the same reaction time. The Lewis acid catalyst activates the carbonyl group in salicylaldehyde (2), which is subsequently able to interact with the 4-CH nucleophilic center of the
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Published 17 Dec 2014

Regio- and stereoselective synthesis of new diaminocyclopentanols

  • Evgeni A. Larin,
  • Valeri S. Kochubei and
  • Yuri M. Atroshchenko

Beilstein J. Org. Chem. 2014, 10, 2513–2520, doi:10.3762/bjoc.10.262

Graphical Abstract
  • aminolysis of epoxides 6a,b afforded mainly C1 adducts 13a,b arising from trans-diaxal opening of the epoxide ring. Using a Lewis acid catalyst, epoxides 6a,b were transformed into diaminocyclopentanols 14a,b via an alternative pathway involving the formation of aziridinium intermediate 17. Keywords
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Published 28 Oct 2014

Facile synthesis of 1H-imidazo[1,2-b]pyrazoles via a sequential one-pot synthetic approach

  • András Demjén,
  • Márió Gyuris,
  • János Wölfling,
  • László G. Puskás and
  • Iván Kanizsai

Beilstein J. Org. Chem. 2014, 10, 2338–2344, doi:10.3762/bjoc.10.243

Graphical Abstract
  • of either a Brønsted or a Lewis acid catalyst (Table 1, entry 1). However, the use of Lewis acids, such as indium(III) salts or TMSCl, improved the reaction rate, with yields up to 67% (Table 1, entries 2–4). The GBB-3CR catalysed by Brønsted acids, including PTSA or HClO4, led to similar yields as
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Published 08 Oct 2014

Solution phase synthesis of short oligoribonucleotides on a precipitative tetrapodal support

  • Alejandro Gimenez Molina,
  • Amit M. Jabgunde,
  • Pasi Virta and
  • Harri Lönnberg

Beilstein J. Org. Chem. 2014, 10, 2279–2285, doi:10.3762/bjoc.10.237

Graphical Abstract
  • precipitate obtained was dissolved in a 5:2 mixture of DCM and MeOH (35 mL) and 5 mL of a 0.125 mol L−1 HCl in MeOH solution were added. After 15 min, pyridine was added to neutralize the acid catalyst. The solution was concentrated to oil and cold MeOH (50 mL) was added. The white precipitate obtained
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Published 29 Sep 2014

Expedient synthesis of 1,6-anhydro-α-D-galactofuranose, a useful intermediate for glycobiological tools

  • Luciana Baldoni and
  • Carla Marino

Beilstein J. Org. Chem. 2014, 10, 1651–1656, doi:10.3762/bjoc.10.172

Graphical Abstract
  • pyranosic analogue 1. Compound 2 was thus obtained in very low yield. More recently, 2 was obtained in 32% yield by heating with a resin as an acid catalyst. Despite the greater smoothness of the method, byproducts were also formed, rendering the purification difficult [14]. Compound 2 obtained by these
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Published 21 Jul 2014

Atherton–Todd reaction: mechanism, scope and applications

  • Stéphanie S. Le Corre,
  • Mathieu Berchel,
  • Hélène Couthon-Gourvès,
  • Jean-Pierre Haelters and
  • Paul-Alain Jaffrès

Beilstein J. Org. Chem. 2014, 10, 1166–1196, doi:10.3762/bjoc.10.117

Graphical Abstract
  • reaction of methanol on the chlorophosphate intermediate. Because the AT reaction is not efficient to produce alkylphosphate from alkylalcohol, an alternative is the usage of chlorophosphate in the presence of a Lewis acid catalyst. For this purpose, Ti(t-BuO)4 was identified as an effective catalyst [52
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Published 21 May 2014

Continuous flow nitration in miniaturized devices

  • Amol A. Kulkarni

Beilstein J. Org. Chem. 2014, 10, 405–424, doi:10.3762/bjoc.10.38

Graphical Abstract
  • mechanism for the electrophilic nitration involves the sequence of reactions depicted below [12]: In the first step, the presence of a strong acid catalyst HA protonates HNO3 thereby releasing the reactive species NO2+ and water in the second step. Both of these steps are rapid and reversible. The third
  • be overlooked without focusing entirely on using the “micro reactor” concept. 3.1.4 Nitration with solid acid catalysts. The continuous flow vapour phase nitration using a solid acid catalyst has also been explored [26]. It is known that the solid acid catalysts, i.e., ZSM and other zeolite catalysts
  • microreactor, concentrated nitric acid reacted very rapidly in the absence of any sulfuric acid or a solid acid catalyst. Nitric acid and toluene were brought into contact by using a SS316L T-mixer (1.58 mm inner diameter) at room temperature. The immiscible reactants were passed through a tubular microreactor
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Published 14 Feb 2014

Boron-substituted 1,3-dienes and heterodienes as key elements in multicomponent processes

  • Ludovic Eberlin,
  • Fabien Tripoteau,
  • François Carreaux,
  • Andrew Whiting and
  • Bertrand Carboni

Beilstein J. Org. Chem. 2014, 10, 237–250, doi:10.3762/bjoc.10.19

Graphical Abstract
  • solvent [31]. The use of a stoichiometric amount of EtAlCl2 as Lewis acid catalyst allowed a lowering of the reaction temperature, a shortening of the reaction time and good stereocontrol (Scheme 2) [32]. Alternatively, the simple heating of a mixture of a 1-bora-1,3-diene, a dienophile and an aldehyde
  • 1,3-diene in a tandem cycloaddition [4 + 2]/allylboration sequence. Lewis acid catalyst in the tandem cycloaddition [4 + 2]/allylboration sequence. Synthesis of an advanced precursor of clerodin. Intramolecular Diels–Alder/allylboration sequence. Diastereoselective Diels–Alder reaction with N
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Published 22 Jan 2014
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