2-(4-Methoxyphenoxy)pyrazine (original) (raw)
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Structural characterisation of 2,3-disubstituted pyrazines: NMR and X-ray crystallography
Journal of Molecular Structure, 2005
2-Formyl-3-aminopyrazine (1), 2-acetyl-3-aminopyrazine (2) and 2-benzoyl-3-aminopyrazine (3) have been studied by multinuclear magnetic resonance spectroscopy in solution and in solid state. Amino-imine tautomerism in such derivatives has been discussed on the basis of the calculated stabilities of the different tautomers by the hybrid B3LYP/6-31G** method. The crystalline structure of compound 3 has been solved, it belongs to the monoclinic P21/n space group, and shows supramolecular architectures involving N–H⋯O and N–H⋯N-pyrazine intermolecular hydrogen bonds.
New Journal of Chemistry, 2004
A series of 2,5-di(aryleneethynyl)pyrazine derivatives has been synthesised in 23-41% yields by twofold reaction of 2,5-dibromo-3,6-dimethylpyrazine 3 with ethynylarenes (arene ¼ phenyl, 2-pyridyl, 4-ethylphenyl, 4-chlorophenyl, 4-biphenyl) under standard Sonogashira conditions [CuI, Pd(PPh 3) 2 Cl 2 , NEt 3 , THF]. Compound 3 has been converted into 2,5-diethynyl-3,6-dimethylpyrazine, which reacts with 2-iodothiophene to yield 2,5-bis(thien-2-ylethynyl)-3,6-dimethylpyrazine. In the X-ray crystal structure of 2,5-di(phenylethynyl)-3,6-dimethylpyrazine 4 the two phenyl rings are parallel and the pyrazine ring is inclined to their planes by 14.2. Quantum chemical calculations establish that the HOMO-LUMO gap for 4 (3.56 eV) is lower than that of di(phenylethynyl)benzene 12 (3.72 eV). The nitrogen atoms of 4 serve to localise the HOMO on the central ring 's carbon atoms, resulting in a quinoidal-type population, in contrast to 12. Cyclic voltammetric studies establish that 4 undergoes a reduction to the radical anion at ca. À1.9 V (vs. Ag/Ag þ in MeCN), which is almost reversible at high scan rates (500 mV s À1). The UV-vis absorption and photoluminescence profiles of 4 in cyclohexane are similar to those of 12; the emission for 4 (l max 379 and 395 nm) is red-shifted compared to 12. Single-layer OLEDs using MEH-PPV as the emissive polymer show significantly enhanced external quantum efficiencies (up to 0.07%) when 20% by weight of 2,5-di(biphenyl-4-ethynyl)-3,6-dimethylpyrazine 8 is added as a dopant: this is ascribed to the enhanced electron-transporting properties of the pyrazine system.
Efficient regioselective heterocyclisation leading to fluorescent fused pyrazine derivatives
Tetrahedron, 2011
The regioselective syntheses of substituted pyrrolo[2,3-b]quinoxaline, pyrido[2,3-b]pyrrolo[2,3-e]pyrazine, pyrido[2,3-b]pyrrolo[3,2-e]pyrazine and pyrido [3,4-b]pyrrolo[3,2-e]pyrazine are reported. Differential reactivity between two amino groups in ortho-diaminopyridine can be exploited to obtain new regio-defined unsymmetrical pyridopyrrolopyrazine derivatives. Weak electron-donating methyl or moderately electron-withdrawing carboxylic groups attached to the aromatic ortho-diamines reduce the regioselectivity of obtaining unsymmetrical substituted pyrrolo[2,3-b]quinoxaline. The fluorescence properties of the resultant 1-alkyl pyridopyrrolopyrazine and substituted pyrrolo[2,3-b]quinoxaline derivatives are presented.
Acta Poloniae Pharmaceutica, 2023
In this study, a series of novel 2-pyrazoline derivatives were synthesized and their structures were established by using spectral methods. The antiproliferative activities of compounds were investigated against human cell lines A-549 and MCF-7 by MTT assay and L-929 (mouse normal fibroblast) cell cytotoxicity was also examined. Apoptotic effects of the compounds in breast and lung cancer cells were assessed by Annexin V-FITC apoptosis assay using flow cytometry. The antiproliferative effect on lung carcinoma of the synthesized compounds was higher than breast carcinoma. Moreover, it was observed that none of the synthesized compounds have cytotoxic activity in healthy cells. Flow cytometry studies have shown that compounds induced apoptosis at high concentrations. Additionally, fluorescence cell imaging studies were performed for the first time in A-549 and MCF-7 cancer cell lines to determine the potential of the biosensor compounds by fluorescence microscopy. Compounds 4b, 4d, 4e, and 4f showed fluorescence properties by considering microscopic imaging.
Unveiling a versatile heterocycle: pyrazoline – a review
RSC Advances, 2017
The design and synthesis of novel fluorescent heterocyclic dyes is a "hotspot" research area, due to their favourable photophysical properties and crucial role in charge transfer processes, which could allow huge advances in the fields of physics, chemistry and biology. One group of electron-rich nitrogen carriers, pyrazolines, are enjoying brisk growth, since they combine exciting electronic properties with the potential for dynamic applications. Concerning multi-functional applications, pyrazolines could provide a new range of applications that would revolutionize various fields. As reported in many studies, the potential applications of pyrazolines are vast and ever growing, but they have yet to make inroads into real-life applications. This review provides an overview on the current status of pyrazoline derivatives in terms of synthesis, physico-chemical properties and various applications in order to realize their full potential for practical applications, and to trigger the synthesis and study of novel pyrazoline based compounds with much promise. We also present our conclusions and outlook for the future. Beena Varghese received her Master's degree in Analytical Chemistry from Mahatma Gandhi University (India) in 2004. She completed her PhD (2015) and Post-doctoral fellowship (2016) at Sultan Qaboos University (Oman) in the research group of Prof. Salma Al-Kindy. Presently, she is working as a visiting faculty member in the Department of Chemistry at Sultan Qaboos University, and her research interests include novel uorescent labels, their analytical applications, and uorescent organic nanoparticles based on electron rich heterocyclic rings for application in biomedicine, sensors and in opto-electronics. Saleh Nasser Al-Busa obtained his MSc (1994) and a PhD (1999) in Organic Chemistry from the University of Reading, Reading, United Kingdom. He has been a member of the RSC (MRSC) since 2012. He joined the Department of Chemistry at Sultan Qaboos University in Sultanate of Oman, in 1991, where he is now an Associate Professor. His research interests include isolation of natural products and the synthesis of uorescent organic labels.
Unequivocal role of pyrazine ring in medicinally important compounds: a review
Mini reviews in medicinal chemistry, 2013
Pyrazine is one of the important class of heterocyclic compounds that can be obtained naturally or synthesized chemically. Pyrazine ring has got importance in exhibiting various biological activities in association with other scaffolds like pyrrole, pyrazole, imidazole, triazole, tetrazole, thiophene, oxazole, pyridine, piperidine and piperazine. Presence of pyrazine ring as a basic scaffold in various clinically used drugs exhibits its importance in drug design. In this review, attempt has been made to disclose various therapeutic applications of pyrazine derivatives reported during the last decade.
N -(4-Bromophenyl)pyrazine-2-carboxamide
Acta Crystallographica Section E Structure Reports Online, 2010
The molecular structure of (I), Fig. 1, is essentially planar with the dihedral angle formed between the pyrazine and benzene rings being 10.2 (3)°; the r.m.s. deviation of all 16 non-H atoms = 0.103 Å (Spek, 2009). The observed conformation is stabilized by an intramolecular N-H•••N hydrogen bond, Table 1. An analysis of the crystal packing reveals C-H•••O, N•••Br, Br•••π, and π-π interactions. The C-H•••O contacts lead to the formation of a supramolecular chain with a flat topology along the a axis. These are sustained in the crystal packing by
Journal of Molecular Structure, 2018
The new compound of 5-(2-Methoxy-4-(prop-1-en-1-yl)phenoxy)pyrazine-2,3-dicarbonitrile was synthesized and structure was characterized by using XRD, FT-IR and NMR techniques. All theoretical computations were calculated by using density functional theory (DFT) B3LYP method with the help of 6-31 þ G(d) basis set. Theoretical calculations help to obtaining detailed information about chemical activity, electrophilic/nucleophilic nature, molecular and chemical properties that can not be obtained by experimental ways. Accordingly, molecular electrostatic potential, hardness/softness parameters, net charges analyses were investigated to gain electrophilic/nucleophilic nature of molecule. Also, the electron density based local reactivity descriptors such as Fukui functions were discussed with regard to electrophilic/nucleophilic nature. The results from natural bond orbital analysis were analyzed interms of the hybridization of atoms and the electronic structure of the title molecule. The stability of the molecule arising from hyperconjugative interactions, charge delocalization was analyzed by using natural bond orbital analysis. The dipole moment (m) and polarizability (a), and first order hyperpolarizability (b) of the molecule was reported and the results of these were given information about the material capability to generate non-linear effects (NLO). The interactions between the molecule with DNA bases such as adenine, cytosine, guanine, and thymine were investigated by using the ECT (electrophilicity-based charge transfer) method and DN (charge transfer).