- Four-Step Domino Reaction Enables Fully Controlled Non-Statistical Synthesis of Hexaarylbenzene with Six Different Aryl Groups**
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Hexaarylbenzene (HAB) derivatives are versatile aromatic systems playing a significant role as chromophores, liquid crystalline materials, molecular receptors, molecular-scale devices, organic light-emitting diodes and candidates for organic electronics. Statistical synthesis of simple symmetrical HABs is known via cyclotrimerization or Diels–Alder reactions. By contrast, the synthesis of more complex, asymmetrical systems, and without involvement of statistical steps, remains an unsolved problem. Here we present a generally applicable synthetic strategy to access asymmetrical HAB via an atom-economical and high-yielding metal-free four-step domino reaction using nitrostyrenes and α,α-dicyanoolefins as easily available starting materials. Resulting domino product—functionalized triarylbenzene (TAB)—can be used as a key starting compound to furnish asymmetrically substituted hexaarylbenzenes in high overall yield and without involvement of statistical steps. This straightforward domino process represents a distinct approach to create diverse and still unexplored HAB scaffolds, containing six different aromatic rings around central benzene core.
- Dill, Maximilian,Grau, Benedikt W.,Hampel, Frank,Jux, Norbert,Kahnt, Axel,Tsogoeva, Svetlana B.
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supporting information
p. 22307 - 22314
(2021/08/25)
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- Exploiting the chiral ligands of bis(Imidazolinyl)-and bis(oxazolinyl)thiophenes—Synthesis and application in Cu-catalyzed friedel–crafts asymmetric alkylation
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Five new C2-symmetric chiral ligands of 2,5-bis(imidazolinyl)thiophene (L1–L3) and 2,5-bis(oxazolinyl)thiophene (L4 and L5) were synthesized from thiophene-2,5-dicarboxylic acid (1) with enantiopure amino alcohols (4a–c) in excellent optical purity and chemical yield. The util-ity of these new chiral ligands for Friedel–Crafts asymmetric alkylation was explored. Subse-quently, the optimized tridentate ligand L5 and Cu(OTf)2 catalyst (15 mol%) in toluene for 48 h promoted Friedel–Crafts asymmetric alkylation in moderate to good yields (up to 76%) and with good enantioselectivity (up to 81% ee). The bis(oxazolinyl)thiophene ligands were more potent than bis(imidazolinyl)thiophene analogues for the asymmetric induction of the Friedel–Crafts asymmetric alkylation.
- Al-Majid, Abdullah Mohammed,Alammari, Abdullah Saleh,Alshahrani, Saeed,Barakat, Assem,Haukka, Matti,Islam, Mohammad Shahidul
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- Co-Polymeric Nanosponges from Cellulose Biomass as Heterogeneous Catalysts for amine-catalyzed Organic Reactions
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Heterogeneous catalysts prepared from biomass waste sources are attracting increasing interest. The reasons rely on the possibility of combining the virtuous approach of circular economy with the consolidated advantages of heterogeneous catalysis, namely the recycling of the system and the possibility to drive selectivity towards desired products. Herein we report a highly porous cellulose-based nanosponge (CNS) and its use as a recoverable catalyst for Henry and Knoevenagel reactions, two classical amino-catalyzed transformations. The material is obtained by cross-linking between TEMPO-oxidized cellulose nanofibers (TOCNF) and branched polyethyleneimine 25 kDa (bPEI) in the presence of citric acid. CNS have been developed as sorbent materials for water remediation but their use as heterogeneous catalysts was never investigated. The fully characterized micro- and nano-porous system guarantees a complete penetration of CNS, allowing reagents to diffuse within. Indeed, by modulating reaction conditions (catalyst loading, temperature, solvent, microwave versus conventional heating, relative ratio of reagents) it was possible to drive selectivity towards the desired products, while maintaining high efficiency in terms of conversion. The catalyst could be re-used several times without losing in catalytic efficiency. In most cases the products’ distribution is quite different from homogeneous conditions, this much more emphasizing the importance of this heterogeneous solution.
- Riva, Laura,Punta, Carlo,Sacchetti, Alessandro
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p. 6214 - 6222
(2020/10/02)
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- Catalyst-free sulfa-Michael addition of pyrimidine-2-thiol to nitroolefins
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Catalyst-free sulfa-Michael addition of pyrimidine-2-thiol to nitroolefins is described. A series of 2-((2-nitro-1-arylethyl)thio)pyrimidines were efficiently synthesized. The protocol has advantages of wide range of substituents tolerance, no catalyst, additives and bases, mild condition, and high yield. The method can also extend to gram scale.
- Li, Zheng,Song, Geyang,He, Jiaojiao,Du, Yan,Yang, Jingya
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p. 686 - 698
(2017/09/06)
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- Chloro/bromotrimethylsilane-Cu(NO3)2·3H2O: Safe and efficient reagent system for the decarboxylative ipso-nitration and dibromination of cinnamic acids
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Further synthetic potential of halotrimethylsilane-nitrate salt mixture is revealed. A mixture of TMSX-Cu(NO3)2·3H2O system is found to be an efficient reagent system for both the decarboxylative nitration (ipso-nitration) when X?=?Cl, and dibromination of cinnamic acids, with X?=?Br, under mild conditions. The reactions are safe and simple, affording the corresponding products (E)-β-nitrostyrenes, and anti-2,3-dibromo-3-phenylpropanoic acids in high yields with high selectivity in a relatively short time. Use of hazardous and toxic nitrating systems such as acetyl nitrate and brominating agents such as molecular bromine can be avoided.
- Roshandel, Sahar,Gurung, Laxman,Mathew, Thomas,Prakash, G.K. Surya
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supporting information
p. 2842 - 2845
(2017/06/27)
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- Tetraarylphosphonium inner-salts (TAPIS) as both Lewis base catalyst and phase tag
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Tetraarylphosphonium inner-salts (TAPIS) have been designed, synthesized and verified as recyclable and reusable Lewis base catalysts. The resulted TAPIS catalyst has been successfully applied in Michael addition, cyanation and trifluoromethylation reactions.
- Guo, Shuhui,Mi, Xueling
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supporting information
p. 2881 - 2884
(2017/07/11)
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- Organocatalytic asymmetric intramolecular aza-Henry reaction: Facile synthesis of trans-2,3-disubstituted tetrahydroquinolines
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An enantio- and diastereoselective organocatalytic intramolecular aza-Henry (nitro-Mannich) reaction has been developed. The trans-2-aryl-3-nitro-tetrahydroquinoline products are obtained in high yields and in good enantioselectivities with a bifunctional
- Maity, Rajendra,Pan, Subhas Chandra
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supporting information
p. 6825 - 6831
(2015/06/25)
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- (1R,2R)-(+)-(1,2)-DPEN-Bonded Sulfonic Acid Resin: A Trifunctional Heterogeneous Catalyst for Asymmetric Michael Additions of Acetone to Nitroolefins
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Based on (1R,2R)-(+)-(1,2)-DPEN skeleton, a series of primary amine-sulfamide bifunctional catalysts were synthesized, which exhibited excellent catalytic performance in the Michael addition of acetone to β-nitrostyrene. Therefore, a trifunctional heterogeneous catalyst was designed and prepared by simple N-sulfonyl reaction of (1R,2R)-(+)-(1,2)-DPEN and sulfonyl chloride resin. It was employed for the aforementioned addition without any additive and satisfactory results (80.5% conversion; 84.3% ee) were obtained. Meanwhile, the structural and textural properties of the catalyst were characterized by infrared spectroscopy (FT-IR), elemental analysis, SEM, and N2 adsorption and desorption experiments. Finally, the generality of the catalyst was investigated.
- Zhang, Chao,Li, Jing,Tian, Jun,Fang, Wangwang,Li, Yang,Chen, Ligong,Yan, Xilong
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supporting information
p. 1248 - 1258
(2015/03/30)
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- Synthesis of β-nitrostyrenes in the presence of sulfated zirconia and secondary amines
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A simple and efficient protocol for the synthesis of β-nitrostyrenes has been achieved by the use of sulfated zirconia-secondary amine (piperidine, pyrrolidine, proline or prolinol) cooperative systems. The condensation of different aldehydes and nitromethane demonstrates the efficiency of this process, which does not require high-temperature reactivation for the reuse of the catalytic material.
- González-Olvera,Vergara-Arenas,Negrón-Silva,Angeles-Beltrán,Lomas-Romero,Gutiérrez-Carrillo,Lara,Morales-Serna
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p. 99188 - 99192
(2015/12/05)
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- An Acid/Base-Regulated Recyclable Strategy for Homogeneous Cinchona Alkaloid-Derived Primary Amine Organocatalysts in Aldol, Vinylogous Michael and Double-Michael Cascade Reactions
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A practical, recyclable strategy for homogeneous cinchona alkaloid-derived primary amine organocatalysts was developed by controlling the solubilities in an aqueous/organic biphasic system through regulating the pH of the aqueous phase, effecting the prot
- Wan, Jingwei,Zhao, Zhiwei,Wang, Falu,Ma, Xuebing
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supporting information
p. 5755 - 5763
(2015/09/15)
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- Hyperbranched polyamines: Tunable catalysts for the Henry reaction
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Hyperbranched polyethylenimine derivatives were successfully employed as catalyst in the Henry reaction. The nitroalcohol products were obtained in excellent yields within short reaction times. A one-pot synthesis of β-nitrostyrenes was developed by using ZnCl2 along with hyperbranched polyethylenimine derivatives. Georg Thieme Verlag Stuttgart New York.
- Ganesan, Subramaniapillai Selva,Ganesan, Asaithampi,Kothandapani, Jagatheeswaran
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supporting information
p. 1847 - 1850
(2014/08/18)
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- Synthesis of indoles from o,β-dinitrostyrenes via indium/acetic acid-mediated Reductive heterocyclizations
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Reductive heterocyclization reactions of various 1-nitro-2-(2-nitroaryl) ethenes to indoles were investigated. In the presence of indium/AcOH in toluene or benzene, 1-nitro-2-(2-nitroaryl)ethenes were cyclized to give corresponding indoles in good yields.
- Lee, Geunsoo,Choi, Jaehwan,Lee, Byung Min,Kim, Byeong Hyo
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p. 155 - 162
(2013/03/13)
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- Regiospecific synthesis of novel cyclic nitrostyrenes and 3-substituted 2-nitronaphthalenes
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A two-step, practical, regiospecific, and readily scalable benzannulation protocol for the preparation of novel 3-alkyl- and 3-aryl-substituted 2-nitronaphthalenes is disclosed. Addition of a β-nitrostyrene or nitroalkene to a solution of freshly prepared lithiated o-tolualdehyde tert-butyl imine first leads to the formation of a nitronate, via rapid 1,4-addition, then an intramolecular aza-Henry reaction takes place to afford a six-membered carbocycle. Subsequent treatment of the reaction mixture with aqueous acid affords novel substituted cyclic nitrostyrenes that can be conveniently aromatized via a one-pot radical-induced bromination and elimination sequence to furnish the corresponding 3-alkyl- or 3-aryl-2-nitronaphthalenes in excellent yields. The straightforward syntheses of 2-aminonaphthalenes, substituted BINAMs, 2-naphthols as well as tricyclic fused 1,2,3-triazoles are also described. Georg Thieme Verlag Stuttgart. New York.
- Keene, Craig,Kuerti, Laszlo
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supporting information
p. 1719 - 1729
(2013/07/26)
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- Direct Henry reactions with modified calcium oxide as solid catalyst
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Commercial CaO was modified simply with benzyl bromide. The modified CaO had good water resistance, and characterization by FTIR and TG revealed the modifier was chemically bonded to the CaO surface. Commercial CaO and CaO modified with benzyl bromide were investigated as catalysts for the Henry reaction between benzaldehyde and nitromethane. It was found that the catalytic activity of the modified CaO was greatly improved, with high conversion of benzaldehyde to the (E)-phenyl nitroolefin and 1-phenyl-2-nitroethanol, and with different selectivity from commercial CaO. The effect of modification and reaction conditions on yield, selectivity, and mechanism were studied thoroughly.
- Tang, Ying,Gu, Xuefan,Meng, Mei,Xu, Jingfang
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p. 3715 - 3725
(2013/10/22)
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- Catalyst functional group cooperativity in the amino acid-catalysed nitroaldol condensation reaction
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Several amino acids and their derivatives have been evaluated as organic catalysts for the nitroaldol reaction. It was found that when an unprotected amino group and an unprotected carboxylate group were present in the organocatalyst, both the nitroaldol reaction and subsequent elimination could occur to afford nitroalkenes from aromatic aldehydes and nitromethane. The best results were obtained by use of γ-amino acids derived from l-glutamine. It is suggested that the amino group is important for intermediate Schiff base formation and that the free carboxylate group facilitates the elimination step.
- Karadeniz, Leman,Astley, Stephen T.
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p. 3407 - 3415
(2013/09/23)
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- What controls regiochemistry in 1,3-dipolar cycloadditions of Muenchnones with nitrostyrenes?
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The distinct experimentally observed regiochemistries of the reactions between mesoionic muenchnones and β-nitrostyrenes or phenylacetylene are shown by DFT/BDA/ETS-NOCV analyses of the transition states to be dominated by steric and reactant reorganization factors, rather than the orbital overlap considerations predicted by Frontier Molecular Orbital (FMO) Theory.
- Lopchuk, Justin M.,Hughes, Russell P.,Gribble, Gordon W.
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supporting information
p. 5218 - 5221
(2013/11/06)
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- An intramolecular nitro-Mannich route to functionalised tetrahydroquinolines
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A simple protocol for the diastereoselective synthesis of 3-nitrotetrahydroquinolines has been developed using an intramolecular nitro-Mannich reaction. In situ formation of an imine generated from treatment of 2-(2-nitroethyl)phenylamine with an aldehyde
- Anderson, James C.,Noble, Adam,Torres, Pascual Ribelles
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supporting information
p. 5707 - 5710
(2012/10/30)
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- Catalyst-free and solvent-free Michael addition of 1,3-dicarbonyl compounds to nitroalkenes by a grinding method
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An environmentally benign, fast and convenient protocol has been developed for the Michael addition of 1,3-dicarbonyl compounds to β-nitroalkenes in good to excellent yields by a grinding method under catalyst- and solvent-free conditions.
- Xie, Zong-Bo,Wang, Na,Wu, Ming-Yu,He, Ting,Le, Zhang-Gao,Yu, Xiao-Qi
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supporting information; experimental part
p. 534 - 538
(2012/06/29)
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- Mesoporous nickel hydroxyapatite nanocomposite for microwave-assisted Henry reaction
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The utility of nickel hydroxyapatite nanocomposite (Ni-HAp) as a green catalyst for solvent free, microwave-assisted Henry reaction using nitromethane and a series of aromatic aldehydes as substrates is presented. The selected catalyst performed well to afford the respective nitrostyrenes which were quantified by gas chromatography equipped with a mass spectral detector (GC-MS). A few of the products were identified from the respective nuclear magnetic resonance (NMR) spectral data.
- Neelakandeswari,Sangami,Emayavaramban,Karvembu,Dharmaraj,Kim, Hak Yong
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experimental part
p. 2980 - 2984
(2012/07/28)
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- An expeditious, highly efficient, catalyst-free and solvent-free synthesis of nitroamines and nitrosulfides by Michael addition
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A simple, atom economical, fast and highly efficient green protocol has been developed for the synthesis of nitroamines and nitrosulfides by the Michael addition of amines and thiols to nitroolefins by simple mixing or grinding. This catalyst-free and solvent-free green approach provided the addition products in quantitative yield within minutes at room temperature. This procedure does not require any water quenches, solvent separations and purification steps such as recrystallization and column chromatography.
- Choudhary, Garima,Peddinti, Rama Krishna
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body text
p. 276 - 282
(2011/04/17)
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- Microwave-induced solvent-free, rapid and efficient synthesis of conjugated nitroalkenes using sulfated zirconia
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Sulfated Zirconia catalyzed synthesis of conjugated nitroalkenes has been carrried out under solvent-free condition using sulfated zirconia. Recyclability of catalyst, isolation of pure products by simple filtration and evaporation are important features of this method.
- Bandgar,Kasture
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p. 1239 - 1241
(2007/10/03)
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- Gel entrapped base catalysed (GEBC) Henry reaction: Synthesis of conjugated nitroalkenes
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A new, simple and practical procedure for direct transformation of aldehydes or ketones and nitromethane into conjugated nitroalkenes by using novel gel entrapped base catalyst (GEBC) has been described.
- Bandgar,Uppalla
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p. 2071 - 2075
(2007/10/03)
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- Morpholine adsorbed on silica gel: A novel and mild basic catalyst for the synthesis of α,β-unsaturated nitroalkenes
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Syntheses of α,β-unsaturated nitroalkenes have been carried out under mild condition using morpholine adsorbed on silica gel as a novel catalyst.
- Bandgar, Babasaheb P.,Uppalla, Lav S.,Sadavarte, Vaibhav S.
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p. 949 - 952
(2007/10/03)
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- Electrophilic Aromatic Substitution. Part 25. The Nitration in Aqueous Sulphuric Acid of Some Cinnamic Acids and Other Styrene Derivatives
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The rates of nitration of ethyl cinnamate, cinnamic acid, β-nitrostyrene, and trimethyl(styryl)ammonium ion in sulphuric acid of a range of concentrations have been determined.The nitrovinyl and the trimethyl(vinyl)-ammonium groups deactivate the aromatic nucleus by factors of ca. 330 and 60, respectively.The yields of products from ethyl cinnamate and β-nitrostyrene, nitrated over a range of sulphuric acid concentrations, are reported.With ethyl cinnamate the o:p ratio falls with increasing acidity.The acidity dependences of the rates of reaction of ethyl-4-nitrocinnamate, 4-nitrocinnamic acid, ethyl 3-nitrocinnamate, and 3-nitrocinnamic acid with nitric acid in sulphuric acid show the primary reaction in each case to be attack by the nitronium ion (at the β-carbon atom).The reactions are completed by addition, giving nitroalcohols.A similar but much slower reaction occurs with β,4-dinitrostyrene.In every case the nitroalcohol decomposes in concentrated sulphuric acid to give the nitrobenzaldehyde.With absolute nitric acid, ethyl 4-nitrocinnamate gives the side-chain nitro-nitrate by formal syn-addition.Addition of nitromethane to the reaction solution leads to addition in both stereochemical modes.The nitro-nitrate gives the nitro-alcohol in sulphuric acid, but in aqueous media gives ethyl α-nitro-β-(4-nitrophenyl)acrylates.These apparent side-chain nitrations are thus addition-elimination reactions, as suggested by van der Lee.Similar processes have been detected in the cases of 4-nitrocinnamic acid and β,4-dinitrostyrene.
- Moodie, Roy B.,Schofield, Kenneth,Taylor, Peter G.,Baillie, Philip J.
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p. 842 - 847
(2007/10/02)
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- Experimental and theoretical investigation of the unusual substituent effect of the vinyl group
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?+ Substituent constants for the orto- and para-vinyl group have been determined by the application of the linear free-energy relationship to the nitration of the β-substituted styrene derivative.Energy changes (relative to benzene system) for the proton and hydride ion transfer to individual positions in the styrene molecule have been calculated.Both approaches indicate that the vinyl group is capable of stabilizing both positively and negatively charged transition states.The interactions of the vinyl group with other substituents in the phenyl ring are also determined.Again, stabilizing effects with respect to both ?-donor and ?-acceptor substituents have been demonstrated for the vinyl group.
- Reynolds, W.F.,Modro, T.A.
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p. 412 - 418
(2007/10/02)
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- Research on antitumor chemotherapy: X. β Nitrostyrene and nitrovinyl derivatives
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In previous work, the antitumoral cytotoxicity of β nitrostyrenes obtained by simplification of the aristolochic acid molecule was demonstrated. The effect of modifying the 3 characteristic parts of the β nitrostyrene molecule was then investigated. Results in vitro and in vivo indicate a probable mechanism of action for the β nitrostyrene and nitrovinyl compounds studied, and permit definition of the maximum simplification compatible with retention of biological activity.
- Dore,Viel
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