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Synthesis of some D-homo-D-aza estratriene derivatives
Petrovi? Julijana A.,Saka? Marija N.,Penov-Ga?i Katarina M.,Pejanovi? Vjera M.
Acta Periodica Technologica , 2004, DOI: 10.2298/apt0435225p
Abstract: In this paper two synthetic routes for obtaining D-homo-D-aza estratriene derivatives were described. Namely, starting from 3-methoxyestra-1,3,5(10)-trien-16-oximino-17-one (1) 3-methoxy-17-aza-D-homoestra-1,3,5(10)-triene (5) was synthesized in two step. Another D-aza derivative was synthesize, starting from 3-methoxy-17-oxo-16,17-secoestra-1,3,5(10)-trien-16-nitrile (6). For that purpose, the seco-cyanoaldehyde was converted into its 17-ethylenacetal 7 followed by subsequent reduction of the nitrile function with sodium borohydride in the presence of cobalt chloride hexahydrate. Finally, under acidic conditions the obtained 16-amino-17-ethylenacetal 8 was transformed into 3-metoxy-17-aza-D-homoestra-1,3,5(10),17(17a)-tetraene (9).
Partitioning of π-electrons in rings of aza-derivatives of naphthalene
IVAN GUTMAN,BORIS FURTULA,RADMILA KOVACEVIC
Journal of the Serbian Chemical Society , 2007,
Abstract: A recently proposed method for calculating the π-electron contents (EC) of rings of heteroatom-containing polycyclic conjugated molecules was applied to the aza-derivatives of naphthalene. The main finding was that a nitrogen atom in position α (resp. β) diminishes (resp. increases) the EC-value of the respective ring. Such a regularity in the displacement of π-electrons can be (qualitatively) rationali-zed by means of resonance-theoretical reasoning.
Synthesis, Cytotoxicity and Antileishmanial Activity of Aza-stilbene derivatives  [PDF]
Elaine S. Coimbra
Mediterranean Journal of Chemistry , 2013,
Abstract: Stilbenes are compounds found in numerous medicinal plants and food products with some known biological and even antileishmanial activity. This paper describes the preparation of Aza-stilbene derivatives and their in vitro biological activities against Leishmania species. Most of the compounds with hydroxyl groups (2a,2b, 2d, 2e and 2f) showed interesting results against three Leishmania species tested. Compound 2f showed the best activity against intracellular forms of L. amazonensis, with IC50 of 7.48 μM, very similar when compared to reference drug Miltefosine. It not possible associate NO production with leishmanicidal activity for all azastilbene derivatives. It is noteworthy that none of compounds tested showed cytotoxicity against macrophages
Adsorption of cytosine and aza derivatives of cytidine on Au single crystal surfaces  [PDF]
M. Iakhnenko,V. Feyer,N. Tsud,O. Plekan,F. Wang,M. Ahmed,O. Slobodyanyuk,R. G. Acres,V. Matolín,K. C. Prince
Physics , 2013,
Abstract: The adsorption of cytosine on the Au(111) and Au(110) surfaces has been studied using both aqueous deposition and evaporation in vacuum to prepare the samples. Soft X-ray photoelectron spectroscopy (XPS) and near edge X-ray absorption fine structure spectroscopy (NEXAFS) were used to determine the electronic structure and orientation of the adsorbates. In addition, three derivatives of cytosine, 6-azacytosine, 6-azacytidine and 5- azacytidine, were studied. Monolayer films of the latter three samples were adsorbed on Au(111) from aqueous solution, and the nature of bonding was determined. Spectra have been interpreted in the light of published calculations of free cytosine molecules and new ab initio calculations of the other compounds. Surface core level shifts of Au 4f imply that all of these compounds are chemisorbed. Cytosine adsorbs as a single tautomer, but in two chemical states with different surface-molecule bonding. For deposition in vacuum, a flat-lying molecular state bonded through the N(3) atom of the pyrimidine ring dominates, but a second state is also present. For deposition from solution, the second state dominates, with the molecular plane no longer parallel to the surface. This state also bonds through the N(3) atom, but in addition interacts with the surface via the amino group. Two tautomers of 6-azacytosine were observed, and they and 6-azacytidine adsorb with similar geometries, chemically bonding via the azacytosine ring. The ribose ring does not appear to perturb the adsorption of azacytidine compared with azacytosine. The azacytosine ring is nearly but not perfectly parallel to the surface, like 5-azacytidine, which adsorbs as an imino tautomer. ...
Organocatalytic cascade aza-Michael/hemiacetal reaction between disubstituted hydrazines and α,β-unsaturated aldehydes: Highly diastereo- and enantioselective synthesis of pyrazolidine derivatives  [cached]
Zhi-Cong Geng,Jian Chen,Ning Li,Xiao-Fei Huang
Beilstein Journal of Organic Chemistry , 2012, DOI: 10.3762/bjoc.8.195
Abstract: The catalytic synthesis of nitrogen-containing heterocycles is of great importance to medicinal and synthetic chemists, and also a challenge for modern chemical methodology. In this paper, we report the synthesis of pyrazolidine derivatives through a domino aza-Michael/hemiacetal sequence with chiral or achiral secondary amines as organocatalysts. Thus, a series of achiral pyrazolidine derivatives were obtained with good yields (up to 90%) and high diastereoselectivities (>20:1) with pyrrolidine as an organocatalyst, and enantioenriched pyrazolidines are also achieved with good results (up to 86% yield, >10/1 regioselectivity, >20:1 dr, 99% ee) in the presence of (S)-diphenylprolinol trimethylsilyl ether catalyst.
Antibacterial activity of cobalt(II) complexes with some benzimidazole derivatives  [PDF]
S. O. PODUNAVAC-KUZMANOVIC,V. M. LEOVAC,D. D. CVETKOVIC
Journal of the Serbian Chemical Society , 2008,
Abstract: The antibacterial activities of cobalt(II) complexes with two series of benzimidazoles were evaluated in vitro against three Gram-positive bacterial strains (Bacillus cereus, Staphylococcus aureus, and Sarcina lutea) and one Gram-negative isolate (Pseudomonas aeruginosa). The minimum inhibitory concentration was determined for all the complexes. The majority of the investtigated complexes displayed in vitro inhibitory activity against very persistent bacteria. They were found to be more active against Gram-positive than Gram-negative bacteria. It may be concluded that the antibacterial activity of the compounds is related to the cell wall structure of the tested bacteria. Comparing the inhibitory activities of the tested complexes, it was found that the 1-substituted-2-aminobenzimidazole derivatives were more active than complexes of 1-substituted-2-amino-5,6-dimethylbenzimidazoles. The effect of chemical structure on the antibacterial activity is discussed.
An Efficient One-Pot Multicomponent Synthesis of 4-Aza-Podophyllotoxin Derivatives in Ionic Liquid  [PDF]
Hossein Naeimi,Zahra Rashid,Amir Hassan Zarnani,Ramin Ghahremanzadeh
Journal of Chemistry , 2013, DOI: 10.1155/2013/169695
Abstract: A simple, green, and efficient procedure for the synthesis of 4-aza-podophyllotoxin derivatives by using a one-pot three-component reaction of benzaldehydes, 1,3-cyclohexanediones, and anilinolactones in the presence of catalytic amount of alum in 1-butyl-3-methylimidazolium triflate as green media is described. This reaction proceeded under mild conditions with the use of an inexpensive and readily available catalyst, high to excellent yields, and simple workup procedure. 1. Introduction Multicomponent reactions (MCRs) are one-pot processes in which three or more reactants come together in a single reaction vessel to give a final product containing substantial elements of all the reactants [1–4], and in recent year much attention has been directed toward the one-pot multicomponent reactions, because of their wide range of applications in pharmaceutical chemistry for the production of structural scaffolds and combinatorial libraries for drug discovery [5–8]. The strategies of MCRs offer significant advantages over conventional linear-type syntheses because of high degree of atom economy, high selectivity, and procedural simplicity due to formation of carbon-carbon and carbon-heteroatom bonds in one-pot procedure [9–11]. MCRs, particularly those performed in green and eco-friendly media, have become increasingly useful tools for the synthesis of chemically and biologically important compounds because of their environmentally friendly atom economy and green characteristics, and the “greening” of global chemical processes has became a major issue in the chemical industry [12, 13]. Organic reactions in ionic liquid (IL) media have received the considerable attention of synthetic organic chemists in recent years; IL is an environmentally friendly solvent with unique properties such as high ionic conductivity, nonvolatility, high thermal stability, nonflammability, and miscibility with organic compounds, especially with the heterocyclic compounds [14–17]. Because of these useful properties numerous works have been published in the last decades reporting the possibility to perform several organic reactions and catalyzed processes in these green media [18–20]. 1,4-Dihydropyridine compounds are molecules based upon pyridine and this nucleus is one of the significant core structures among the most extensively natural and unnatural heterocyclic compounds, have been recognized as vital drugs for the treatment of cardiovascular diseases, and are well known as calcium channel modulators [21, 22]. 1,4-Dihydropyridine derivatives exhibit a variety of biological
Cobalt(II) Chloride Hexahydrate as an Efficient and Inexpensive Catalyst for the Preparation of Biscoumarin Derivatives  [PDF]
Mohammad Reza Nazarifar
Advances in Chemistry , 2014, DOI: 10.1155/2014/340786
Abstract: Cobalt(II) chloride hexahydrate (CoCl2·6H2O) has been found to be an efficient catalyst for the one-pot synthesis of biscoumarin derivatives through a combination of aromatic aldehydes and 4-hydroxycoumarin in aqueous media at 70°C. Several types of aromatic aldehyde, containing electron-withdrawing groups as well as electron-donating groups, were used in the reaction and in all cases the desired products were synthesized successfully. The present approach offers remarkable advantages such as short reaction times, excellent yields, straightforward procedure, easy purification, environment friendliness, and low catalyst loading. 1. Introduction Coumarin derivatives, especially biscoumarins, are important compounds in organic synthesis due to their wide spectrum of pharmacological properties such as antifungal, anti-HIV, anticancer, anticoagulant, antithrombotic, antimicrobial, and antioxidant [1–5]. These compounds are also utilized as urease inhibitors [6]. A number of methods have been reported for the synthesis of these compounds in the presence of various catalysts like molecular iodine [7], sodium dodecyl sulfate (SDS) [8], tetrabutylammonium bromide (TBAB) [9], ([][HSO4]) [10], tetrabutylammonium hexatungstate ([W6O19]) [11], sulfated titania (TiO2/) [12], ruthenium(III) chloride hydrate (·) [13], n-dodecylbenzene sulfonic acid (DBSA) [14], and silica chloride nanoparticles (nano SiO2Cl) [15]. However, these methods suffer from one or more disadvantages such as low yields of products, long reaction times, use of expensive catalyst, toxic solvents, or harsh reaction conditions. Therefore, introducing a clean procedure by the use of green and environmentally friendly catalyst with high catalytic activity, moderate temperature, and short reaction time accompanied with excellent yield for the production of biscoumarin derivatives is needed. We hoped to develop a more general protocol for the efficient synthesis of biscoumarin derivatives via ·, which have recently attracted much attention as catalyst to organic synthesis due to their low toxicity and easy availability [16–18]. 2. Results and Discussion We herein present efficient and eco-friendly procedure for the synthesis of biscoumarin derivatives (3 a–m) by three-component condensation of 4-hydroxycoumarin (1) and aromatic aldehyde (2) catalyzed by · in water-ethanol solvent system 70°C (Scheme 1). Scheme 1: Synthesis of biscoumarins. For this study, a reaction between 4-hydroxycoumarin (2?mmol) and 3-nitrobenzaldehyde (1?mmol) was examined as the model reaction. Initial studies showed that better
Recherches récentes sur le cobalt carbonyle et ses dérivés Recent Studies of Cobalt Carbonyl and Its Derivatives
Poilblanc R.,Attali S.,Arabi M. S.,Labroue D.
Oil & Gas Science and Technology , 2006, DOI: 10.2516/ogst:1974018
Abstract: Faisant le point sur l'ensemble de leurs résultats obtenus au cours des dernières années, les auteurs développent divers aspects relatifs aux synthèses, à la physico-chimie et aux structures des complexes dérivés des cobalt carbonyle. L'étude concerne essentiellement : - les dérivés de simple substitution de l'octacarbonyle dicobalt et la tautomérie des complexes dinucléaires; - les dérivés mononucléaires ioniques et leur relation avec les formes alkyle et acétyle du cobalt (I); - le bis (tétracarbonyle cobalt) mercure et ses dérivés de substitution ; - les dérivés tétranucléaires et le phénomène de migration intramoléculaire des ligands. Les caractéristiques spectrographiques de quelque soixante-dix complexes sont fournies en annexe. The authors review their findings concerning the synthesis, physico-chemical properties and structural nature of cobalt carbonyl derivatives. The article deals with : - Normal substitution of Col (CO),, and tautomerism of binuclear complexes; - lonic mononuclear derivatives in relation with alkyl and acetylcobaltcarbonyls ; - Bis (tetracarbonylcobalt) mercury and its substituted derivatives ; - Tetranuclear cobalt complexes exhibiting intramolecular scrambling. Spectrographic data of some 70 compounds are given.
Studies with aza-heterocyclic N-oxides: Synthesis of some new aromatic N-oxide derivatives  [cached]
Ahmed Ali Fadda,Fathy Mohamed Abdelrazek,Ahmed Mahmoud Fouda
European Journal of Chemistry , 2011, DOI: 10.5155/eurjchem.2.1.51-57.249
Abstract: Benzofuroxan derivative (1a) reacts with the cyanoacetanilides (2a-d) to give the benzimidazole derivatives (3a-d). Benzofuroxan (1b) reacts with rhodanine derivatives (4a,b) in presence of sodium ethoxide to give the arylaminobenzoimidazole derivatives (6a,b); while the last reaction afforded the thiazolidinone derivatives (8a,b) and the o-benzoquinone dioxime derivatives (9a,b) when it was repeated in the presence of sodium acetate. Moreover, a series of quinoxalinyl 1,4-di-N-oxide derivatives were prepared starting from quinoxalin-1,4-di-N-oxide derivatives (10a-c). Plausible mechanisms to account for the formation of the products are discussed.
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