5670-67-7Relevant academic research and scientific papers
Four-Step Domino Reaction Enables Fully Controlled Non-Statistical Synthesis of Hexaarylbenzene with Six Different Aryl Groups**
Dill, Maximilian,Grau, Benedikt W.,Hampel, Frank,Jux, Norbert,Kahnt, Axel,Tsogoeva, Svetlana B.
supporting information, p. 22307 - 22314 (2021/08/25)
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.
Exploiting the chiral ligands of bis(Imidazolinyl)-and bis(oxazolinyl)thiophenes—Synthesis and application in Cu-catalyzed friedel–crafts asymmetric alkylation
Al-Majid, Abdullah Mohammed,Alammari, Abdullah Saleh,Alshahrani, Saeed,Barakat, Assem,Haukka, Matti,Islam, Mohammad Shahidul
, (2021/12/17)
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.
Co-Polymeric Nanosponges from Cellulose Biomass as Heterogeneous Catalysts for amine-catalyzed Organic Reactions
Riva, Laura,Punta, Carlo,Sacchetti, Alessandro
, p. 6214 - 6222 (2020/10/02)
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.
Catalyst-free sulfa-Michael addition of pyrimidine-2-thiol to nitroolefins
Li, Zheng,Song, Geyang,He, Jiaojiao,Du, Yan,Yang, Jingya
, p. 686 - 698 (2017/09/06)
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.
Chloro/bromotrimethylsilane-Cu(NO3)2·3H2O: Safe and efficient reagent system for the decarboxylative ipso-nitration and dibromination of cinnamic acids
Roshandel, Sahar,Gurung, Laxman,Mathew, Thomas,Prakash, G.K. Surya
supporting information, p. 2842 - 2845 (2017/06/27)
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.
Tetraarylphosphonium inner-salts (TAPIS) as both Lewis base catalyst and phase tag
Guo, Shuhui,Mi, Xueling
supporting information, p. 2881 - 2884 (2017/07/11)
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.
Organocatalytic asymmetric intramolecular aza-Henry reaction: Facile synthesis of trans-2,3-disubstituted tetrahydroquinolines
Maity, Rajendra,Pan, Subhas Chandra
supporting information, p. 6825 - 6831 (2015/06/25)
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
(1R,2R)-(+)-(1,2)-DPEN-Bonded Sulfonic Acid Resin: A Trifunctional Heterogeneous Catalyst for Asymmetric Michael Additions of Acetone to Nitroolefins
Zhang, Chao,Li, Jing,Tian, Jun,Fang, Wangwang,Li, Yang,Chen, Ligong,Yan, Xilong
supporting information, p. 1248 - 1258 (2015/03/30)
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.
Synthesis of β-nitrostyrenes in the presence of sulfated zirconia and secondary amines
González-Olvera,Vergara-Arenas,Negrón-Silva,Angeles-Beltrán,Lomas-Romero,Gutiérrez-Carrillo,Lara,Morales-Serna
, p. 99188 - 99192 (2015/12/05)
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.
An Acid/Base-Regulated Recyclable Strategy for Homogeneous Cinchona Alkaloid-Derived Primary Amine Organocatalysts in Aldol, Vinylogous Michael and Double-Michael Cascade Reactions
Wan, Jingwei,Zhao, Zhiwei,Wang, Falu,Ma, Xuebing
supporting information, p. 5755 - 5763 (2015/09/15)
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
