1489-06-1Relevant academic research and scientific papers
Star-shaped Keggin-type heteropolytungstate nanostructure as a new catalyst for the preparation of quinoxaline derivatives
Masteri-Farahani, Majid,Ghorbani, Melika,Ezabadi, Ali,Farrokhinia, Niki,Ghaemmaghami, Atekeh-Sadat
, p. 1136 - 1143 (2014)
In this work, we report the novel successful preparation of the Keggin-type Cs(CTA)2PW12O40 (CTA = cetyltrimethylammonium cation) nanostructure by a microemulsion method. The microemulsion system included the cationic surfactant CTAB, 1-butanol as co-surfactant, isooctane as oil phase, and an aqueous solution containing CsNO3. The Cs(CTA)2PW12O40 nanostructure was formed by the addition of an aqueous solution of phosphotungstic acid to the microemulsion solution. Characterization of the resultant nanostructure was done using FT-IR spectroscopy, X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray analysis, and CHN elemental analysis. The product was found to be a star-shaped nanostructure composed of some nanorods whose diameter and length are about 100 nm and 500 nm, respectively. The prepared nanostructure was used as a recoverable catalyst for the synthesis of quinoxaline derivatives by the condensation of 1,2-diamines with 1,2-dicarbonyl compounds, which afforded the products in good to high yields in short reaction times.
Zirconium(IV)-modified silica gel: Preparation, characterization and catalytic activity in the synthesis of some biologically important molecules
Sharma,Sharma, Chetna
, p. 327 - 331 (2011)
Zirconium modified silica gel was prepared by the grafting method and the resulting organic-inorganic hybrid material was found to be a highly effective catalyst for the range of organic transformations such as syntheses of coumarins, quinoxalines and 2,4
Synthesis of a polymer-capped palladium nanoparticles and its application as a reusable catalyst in oxidative coupling reaction of α-hydroxyketones and 1,2-diamines for preparation of pyrazines and quinoxalines
Zarchi, Mohammad Ali Karimi,Abadi, Seyed Shahab Addin Darbandizadeh Mohammad
, p. 915 - 929 (2018)
A novel method for the synthesis of pyrazines and quinoxalines has been developed using α-hydroxyketones and 1,2-diamines in the presence of cross-linked poly(4-vinylpyridine)-stabilized Pd(0) nanoparticles, [P4-VP]-PdNPs. The catalyst was easily prepared and characterized using various techniques such as FT-IR and UV–Vis spectroscopy, AAS, TEM, FESEM, EDX analysis and XRD. The results confirm a good dispersion of palladium nanoparticles on the polymer support. The catalyst displayed good catalytic activity when applied to the synthesis of quinoxalines via condensation of α-hydroxyketones with 1,2-diamines. A few pyrazine derivatives and various quinoxalines are prepared via coupling reaction of α-hydroxyketones and 1,2-diamines in high–excellent yields (81–99%) with short reaction times. The quinoxalines products were characterized by FT-IR, 1H and 13C NMR spectroscopy, and the physical properties were compared to the literature values of known compounds. The advantages of the present method over conventional classical methods are rapid and very simple work-up, and the catalyst is reusable many times without a significant loss in its activity.
Nano SbCl5.SiO2: An efficient catalyst for the synthesis of quinoxaline derivatives at room temperature under solventless condition
Bamoniri, Abdolhamid,Mirjalili, Bibi Fatemeh,Karbasizadeh, Hassan
, p. 2851 - 2856 (2015)
Nano SbCl5.SiO2 as an eco-friendly and efficient nanocatalyst was applied for quinoxaline derivatives preparation with improved yield. In this protocol, α-diketones and 1,2-diamines were condensed in the presence of nanocatalyst at room temperature under solventless conditions. The method gave good yields of quinoxaline derivatives in short reaction times in comparison with earlier methods. Using nontoxic and inexpensive materials, simple work-up, short reaction times and high yields of the products are the advantages of this method.
Iodine-mediated efficient synthesis of 2,3-dihydro-pyrazines
Dong, Yansheng,Huang, Li,Yi, Fengping
, p. 430 - 432 (2015)
The synthesis of 2,3-dihydro-pyrazines has been developed by an efficient protocol of annulations of 1,2-diketones and ethylenediamine. A variety of 2,3-dihydro-pyrazines were prepared in high yields in the presence of a catalytic amount of iodine.
A new catalytic method for eco-friendly synthesis of quinoxalines by zirconium (IV) oxide chloride octahydrate under mild conditions
Jafarpour, Maasoumeh,Rezaeifard, Abdolreza,Heidari, Mahdieh
, p. 202 - 209 (2011)
An environmentally benign catalytic method for efficient synthesis of quinoxaline derivatives via the condensation reaction of 1,2-diamines and 1,2-dicarbonyl compounds using ZrOCl2.8H2O in EtOH as a standard green solvent under mild conditions has been developed. The reusability of the catalyst has been successfully examined without any noticeable loss of its catalytic activity.
An Improved Synthesis of Multi-Substituted Pyrazines under Catalyst- and Solvent-Free Conditions
Tamaddon, Fatemeh,Tafti, Arefeh Dehghani,Pooramini, Farzaneh
, p. 4295 - 4299 (2016)
A one-pot pseudo four-component reaction between a variety of 2-hydroxy-1,2-diarylethanone derivatives and ammonium acetate or amines has been developed to synthesize substituted pyrazines under catalyst-free and solvent-free conditions. This procedure provides a synthetic method to access pyrazine derivatives in excellent yields under green conditions.
Increasing the triplet lifetime and extending the ground-state absorption of biscyclometalated Ir(III) complexes for reverse saturable absorption and photodynamic therapy applications
Wang, Chengzhe,Lystrom, Levi,Yin, Huimin,Hetu, Marc,Kilina, Svetlana,McFarland, Sherri A.,Sun, Wenfang
, p. 16366 - 16378 (2016)
The synthesis, photophysics, reverse saturable absorption, and photodynamic therapeutic effect of six cationic biscyclometalated Ir(iii) complexes (1-6) with extended π-conjugation on the diimine ligand and/or the cyclometalating ligands are reported in this paper. All complexes possess ligand-localized 1π,π? absorption bands below 400 nm and charge-transfer absorption bands above 400 nm. They are all emissive in the 500-800 nm range in deoxygenated solutions at room temperature. All complexes exhibit strong and broad triplet excited-state absorption at 430-800 nm, and thus strong reverse saturable absorption for ns laser pulses at 532 nm. Complexes 1-4 are strong reverse saturable absorbers at 532 nm, while complex 6 could be a good candidate as a broadband reverse saturable absorber at 500-850 nm. The degree of π-conjugation of the diimine ligand mainly influences the 1π,π? transitions in their UV-vis absorption spectra, while the degree of π-conjugation of the cyclometalating ligand primarily affects the nature and energies of the lowest singlet and emitting triplet excited states. However, the lowest-energy triplet excited states for complexes 3-6 that contain the same benzo[i]dipyrido[3,2-a:2′,3′-c]phenazine (dppn) diimine ligand but different cyclometalating ligands remain the same as the dppn ligand-localized 3π,π? state, which gives rise to the long-lived, strong excited-state absorption in the visible to the near-IR region. All of the complexes exhibit a photodynamic therapeutic effect upon visible or red light activation, with complex 6 possessing the largest phototherapeutic index reported to date (>400) for an Ir(iii) complex. Interactions with biological targets such as DNA suggest that a novel mechanism of action may be at play for the photosensitizing effect. These Ir(iii) complexes also produce strong intracellular luminescence that highlights their potential as theranostic agents.
Design and construction of copper(I) complexes based on flexi-dentate cyclic N2-donor Schiff bases via in situ reduction of copper(II) precursors
Jana, Subrata,Chattopadhyay, Shouvik
, p. 298 - 307 (2014)
Three copper(I) complexes [Cu(μ2-L1)I]n (1), [CuL1(μ-1,1,3-SeCN)]n (2) and [Cu 2(μ2-I)2(L2)2] (3), where L1 = 5,6-diphenyl-2,3-dihydro
H3PW12O40/MCM-41 nanoparticles as efficient and reusable solid acid catalyst for the synthesis of quinoxalines
Abdollahi-Alibeik, Mohammad,Heidari-Torkabad, Ezzat
, p. 517 - 523 (2012)
The condensation reaction of 1,2-diketones and o-phenylenediamines was investigated in the presence of nano-sized mesoporous silica (MCM-41) supported 12-tungstophosphoric acid (TPA) as solid acid catalyst. Nano-sized MCM-41 was synthesized and the catalysts with different loading amounts of TPA (5-15 wt.%) were prepared and characterized by XRD, FT-IR and SEM techniques. The results confirm good dispersion of TPA on the solid support. The catalyst is reusable many times without loss in its activity.
