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Tetrahydroquinolines and Isoxazoles: Nitrogen heterocycles as potential antibacterial agents

Tetrahydroquinolines and Isoxazoles: Nitrogen heterocycles as potential antibacterial agents

Nitrogen heterocycles are a part of a special group of organic substances found in many biologically active natural and synthetic products with properties pharmacologically relevant. The synthesis and spectroscopic characterization of tetrahydroquinolines (THQs) and isoxazole are shown. These compounds were evaluated for their in vitro antibacterial activity against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Acinetobacter baumannii. With the purpose of evaluate the structural features in the antibacterial activity, in the present work, some substituents such as: methyl, methoxy and hydrogen in different positions on the THQ ring are reported.

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Investigating Hydrothermal and Radiation Effects on Nitrogen Heterocycles Relevant to Meteorite Parent Bodies

Investigating Hydrothermal and Radiation Effects on Nitrogen Heterocycles Relevant to Meteorite Parent Bodies

In this study, HPLC with UV detection was used for qualitative identification of nitrogen heterocycles. Initially, 15 nitrogen heterocycles were chosen for analysis as they are either known to be produced in room temperature cyanide reactions or are found in formic acid extracts of meteorites. Many nitrogen heterocycles, including nucleobases, have a significant UV absorbance at 260 nm or nearby. The exception to this was s-triazine whose lambda max is near 200 nm and has virtually no detectable absorbance at the monitoring wavelength of 260 nm. Therefore, triazines were not searched for in the supernatant samples due to current instrumental limitations. Triazines have been previously shown to be produced in cyanide reactions and have been identified in meteorite extracts. 47

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Synthesis of nitrogen heterocycles via amidyl radical cyclisations

Synthesis of nitrogen heterocycles via amidyl radical cyclisations

Crotyl alcohol (8.53 ml, 0.1 mol), triethylorthoacetate (46 pi, 0.25 mol) and hexanoic acid (85 pi, 6 mmol) were added to a dried flask which was set up for distillation. The solution was heated in an oil bath with distillation of ethanol. Additional portions of hexanoic acid were added after 3, 3.5 and 4.5 hours. After 6 hours, the solution was cooled and potassium hydroxide (0.1 mol) in water (3 ml) and methanol (75 ml) was added. The reaction mixture was heated at reflux for 1 hour under nitrogen. After cooling to room temperature the solution was washed 3 times with diethyl ether (ether washings discarded) and then acidified with concentrated hydrochloric acid before being extracted with diethyl ether. The organic extracts were dried over anhydrous magnesium sulphate and concentrated on a rotary evaporator to give 3-methylpent-4-enoic acid as a yellow oil (74%) which was used without further purification.1,3 Spectral details matched those published.

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Synthesis and evaluation of some nitrogen heterocycles as antimalarials

Synthesis and evaluation of some nitrogen heterocycles as antimalarials

N - [ 6 - ( 7 ,-Trifluoromethylquinolin-4’-yl)hex-5-en-l-yl]phthalimide (VII.38) 4-Bromo-7-trifluoromethylquinoline (2.3 g), A-(hex-5-en-l-yl)phthalimide (2.1 g), palladium acetate (0.020 g), tri-o-tolylphosphine (0.053 g), sodium iodide (0.030 g) and tributylamine (2.0 ml) in dimethylformamide (3.0 ml) were heated at 100° under nitrogen for 17 h. The residue was diluted with water, extracted with ethyl acetate, and the extract washed with dilute hydrochloric acid, saturated sodium bicarbonate solution, water, and then dried (Na 2 SC> 4 ). The solvent was evaporated and the product subjected to column chromatography (alumina; 10-15% ethyl acetate in hexane) and recrystallised from ethanol to give white crystals of the title compound (0.719 g), m.p. 103.5-105° (Found: C, 67.8; H, 4.7; N, 6.5. C 24 H 19 F 3 N 2 O 2 requires C, 67.9; H, 4.5; N, 6.6%). *H n.m.r. 5 1.70, complex, H2,3; 2.44, complex, H4; 3.76; t, J 7 Hz, HI; 6.47, dt, 15,6 16 Hz, 14,5 7 Hz,

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Kinetic and NMR studies of some nitrogen heterocycles

Kinetic and NMR studies of some nitrogen heterocycles

various pyrrole derivatives with diazonium ions. Butler, Pogorzelec and Shepherd^ studied the kinetics and products of the reaction of pyrrole and substituted derivatives and proposed the mechanism shown in Scheme 1. Imidazole and its methylated derivatives also react with diazonium ions to give highly coloured products. As part of an extension of the investigation into the reactions of pyrrole reactions with diazonium ions, the mechanism of the imidazole reaction was compared with that of pyrrole. It was expected that the two mechanisms would be similar, the extra ring nitrogen present in imidazole having little effect except to reduce the susceptibility of the ring to electrophilic attack. One of the most important previous studies is that due to Ridd et aP. In 1953 they reported an investigation into the kinetics of the diazo-coupling reaction of imidazole and proposed that reaction proceeds via an anionic intermediate. Preliminary kinetic studies confirmed that imidazole reacts more slowly with diazonium ions than pyrrole, consistent with the electron withdrawing effect of the second nitrogen. Further kinetic work, however, did not confirm a mechanism of the type shown in Scheme 1 but was consistent with reaction via the imidazole anion. The aim of this work was to confirm the anionic intermediate by the use of a variety of experimental techniques not available to Ridd et al, in 1953.

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A radical approach to nitrogen heterocycles

A radical approach to nitrogen heterocycles

Therefore, it can be assumed that the radicals cyclise via a ‘chair-like’ transition state with the methyl group in an equatorial position. This could be confirmed by MO calculations (AMI and DFT) that showed that the transition state for cyclisation of [107a] to the trans isomer cyclised product [116a] was lower in energy than that to the corresponding cis isomer cyclised product [117a], The greatest diastereoselectivity was established when the nitrogen substituent was a methoxycarbonyl group It was assumed that the electronic nature of the nitrogen may affect the stereoselectivity although how this electronic effect influences the stereoselectivity is less certain This electronic nature, however, was found to increase the rate of the cyclisation presumably due to the greater nucleophilicity of the radical. For the cyclisations with primary alkyl substituents, the diastereoselectivities o f the reactions were similar However, the cyclisation afforded low yields of desired cyclised products due to the difficulty in removing the tin-residues.

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Synthesis of some benzothiazolyl and imidazole derivatives and evaluation of antibacterial activities

Synthesis of some benzothiazolyl and imidazole derivatives and evaluation of antibacterial activities

In this investigation, benzothiazolyl and imidazole derivatives were prepared using a simple, general reaction scheme. By variation of alkyl and aromatic groups, a series of new compounds were prepared and characterized. The potential antimicrobial activities of organic compounds were evaluated against standard drug. The scope of the present investigation provides an opportunity for adopting a simple general scheme of reaction procedure for the synthesis of nitrogen heterocycles that can be used for development of new potential drug molecule.

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Methyl (4 formyl 2 meth­oxy­carbonyl­pyrrol 1 yl)­acetate

Methyl (4 formyl 2 meth­oxy­carbonyl­pyrrol 1 yl)­acetate

nitrogen heterocycles widely used in medicinal chemistry as well as the pharmaceutical and chemical industries and was selected for crystal structure determination in order to elucidate the conformation of the substituents bonded to the pyrrole ring and the extent of -electron delocalization. There is structural evidence that both the 2-methoxycarbonyl and 4- formyl groups interact with the -cloud of the pyrrole ring. The second methoxycarbonyl group at N1 is twisted out of the pyrrole plane due to rotations around the methylene bonds.

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Application of four membered ring chalcogenation reagents to the synthesis of new phosphorus chalcogen heterocycles

Application of four membered ring chalcogenation reagents to the synthesis of new phosphorus chalcogen heterocycles

Treating Lawesson’s reagent with two  molar  equivalents  of alkyl‐ or aryl‐dithiol in  refluxing toluene gave  the  corresponding five‐ and  six‐membered  ring  heterocycles 1–3  in 45%  to  65%  yields,  respectively,  as  shown  in  Scheme 1. Heterocycles 1–3 were obtained as white solids or pastes in good yields, and are soluble in normal  organic solvents such  as  dichloromethane, chloroform, THF, acetonitrile, acetone and so on.  All of the above  heterocycles were found  to be  air‐stable  both as  solids  and  in solution.  The  identity  of  1–3  was  determined  through a combination of mass spectrometric (EI or CI) techniques, and NMR ( 1 H,  13 C and  31 P) spectroscopy. In  all  cases mass  spectrometry found the expected [M] +  or  [M+H] + . The  1 H  and  13 C  spectra of  1–3  show  clearly  the presence of both the aromatic and alkoxy substituents displaying the expected coupling constants. Singlets  at 71.4, 64.7 and 88.4 ppm were observed respectively in their  31 P{ 1 H} NMR spectra. Attempts to prepare ring  systems of more than six‐members from the reaction of LR with longer‐chain [(‐CH 2 ‐) n , n > 3] dithiol precursors 

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Calculation of Molecular Lipophilicity and Drug Likeness for Few Heterocycles

Calculation of Molecular Lipophilicity and Drug Likeness for Few Heterocycles

Log P value for 16 vinyl, nitrogen and sulphur heterocycles were calculated using eight computer programs: HyperChem 7.0 (based on atom contributions), XLOGP (based on atom contributions),KowWin (based on atom/fragment contributions),CLOGP (based on fragmental contributions), ALOGPS 2.1 (based on atom-type electro topological-state indices and neural network modeling), and IA logP (based on atom-type electrotopological-state indices and neural network modeling), miLogP using Molinspiration and MolSoft. The drug likeness has been calculated using Molinspiration and MolSoft programs. Almost all the heterocycles were found to obey Lipinski’s rule of 5 for an orally active drug.

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SYNTHESIS AND BIOLOGICAL ACTIVITIES OF SOME NEW HETEROCYCLES CONTAINING NITROGEN AND SULPHUR

SYNTHESIS AND BIOLOGICAL ACTIVITIES OF SOME NEW HETEROCYCLES CONTAINING NITROGEN AND SULPHUR

Incorporation of oxygen, nitrogen, sulphur, or an atom of a related element into an organic ring structure in place of a carbon atom gives rise to a heterocyclic compound. Since the heterocyclic atom must form more than one bond in order to be incorporated into a ring structure, halogens do not form heterocyclic compounds although they may be substituents on a heterocyclic ring structure. Heterocyclic compounds, like polycyclic ring compounds, are usually known by non-systematic names. They may be either simple aromatic rings or non- aromatic rings. Some examples are pyridine, pyrrole, furan and thiophene.

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Polyethylene glycol embedded tribromide as an efficient and reusable catalyst for the library synthesis of nitrogen containing heterocycles

Polyethylene glycol embedded tribromide as an efficient and reusable catalyst for the library synthesis of nitrogen containing heterocycles

with KBr followed by the addition of molecular bromine to give PEG embedded potassium tribromide as a dark viscous oil. The synthesized material was found to be an efficient, cost effective, environmentally benign and recyclable catalyst for the library synthesis of nitrogen containing heterocyclic compounds via multicomponent coupling reaction. The method offers a set of advantages such as facile synthesis, low cost, recycling ability and high product yields.

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A Multistep Preparation of 3-Aryl-8-Methoxythiazolo [3’, 2’ : 2, 3] [1, 2, 4] Triazino [5, 6-b] Indoles Under Microwave Ir-radiations

A Multistep Preparation of 3-Aryl-8-Methoxythiazolo [3’, 2’ : 2, 3] [1, 2, 4] Triazino [5, 6-b] Indoles Under Microwave Ir-radiations

recorded in nujol mull or KBr on a Perkin-Elmer 842/Beckman IR-20 / Hitachi 215 spectrometers. The proton magnetic resonance spectra were recorded on a VXR-200 MHz or R-32 Perkin-Elmer 90 MHz spectrometer in CDC1 3 or DMSO-d 6 using tetramethylsilane (TMS) as internal reference stadnard. The chemical shifts are expressed in d (ppm) units downfield from TMS. Mass spectra were scanned on a Jeol JMX-DX-300 spectrometer operating at 70 eV. Carbon, hydrogen and nitrogen analyses were carried out on a Yanaco MT-3 (JAPAN) instrument. Thin layer chromatography (TLC) were performed on silica-gel plates using acetone- benzene (1 : 3 or 1 : 2) as solvent system and iodine chamber as visualizing agent.

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The crystal structures and Hirshfeld surface analysis of 6 (naphthalen 1 yl) 6a nitro 6,6a,6b,7,9,11a hexa­hydro­spiro­[chromeno[3′,4′:3,4]pyrrolo­[1,2 c]thia­zole 11,11′ indeno­[1,2 b]quinoxaline] and 6′ (naphthalen 1 yl) 6a′ nitro 6′,6a′,6b′,7′,8′,9′,10

The crystal structures and Hirshfeld surface analysis of 6 (naphthalen 1 yl) 6a nitro 6,6a,6b,7,9,11a hexa­hydro­spiro­[chromeno[3′,4′:3,4]pyrrolo­[1,2 c]thia­zole 11,11′ indeno­[1,2 b]quinoxaline] and 6′ (naphthalen 1 yl) 6a′ nitro 6′,6a′,6b′,7′,8′,9′,10′,12a′ octa­hydro 2H spiro­[ace­naphthyl­ene 1,12′ chromeno[3,4 a]indolizin] 2 one

The stereochemistry, such as regioselectivity and enanti- oselectivity, of heterocyclic compounds (Huisgen, 1984) can be studied by 1,3-dipolar cycloaddition reactions. Against this background and considering the importance of their natural occurrence, biological, pharmacological and medicinal activ- ities, use as synthetic intermediates, as well as in view of our ongoing research on the design of novel heterocycles, we have synthesized the title compounds and report herein their crystal structures.

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Non bonding 1,5 S•••O interactions govern chemo  and enantioselectivity in isothiourea catalyzed annulations of benzazoles

Non bonding 1,5 S•••O interactions govern chemo and enantioselectivity in isothiourea catalyzed annulations of benzazoles

Isothiourea-catalyzed annulations between 2-acyl benzazoles and a , b -unsaturated acyl ammonium intermediates are selectively tuned to form either lactam or lactone heterocycles in good yields (up to 95%) and high ee (up to 99%) using benzothiazole or benzoxazole derivatives, respectively. Computation gives insight into the signi fi cant role of two 1,5-S / O interactions in controlling the structural preorganization and chemoselectivity observed within the lactam synthesis with benzothiazoles as nucleophiles. When using benzazoles the absence of a second stabilizing non-bonding 1,5-S / O interaction leads to a dominant C – H / O interaction in determining structural preorganization and lactone formation.

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An Efficient Synthesis of Ethyl {[3-(hydroxymethyl) quinolin-2-yl]thio}acetate

An Efficient Synthesis of Ethyl {[3-(hydroxymethyl) quinolin-2-yl]thio}acetate

The family of sulfur–nitrogen heterocycles includes highly stable aromatic compounds, that display physicochemical properties with relevance in the design of new materials especially those relating to molecular conductors and magnets. During the past few decades, interest has been rapidly growing in gaining insight into the properties and transformations of these heterocycles. Heterocycles play an important role in biochemical processes because the side groups of the most typical and essential constituents of living cells, DNA and RNA, are based on aromatic heterocycles 1 . The interesting characteristics found in

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Facile synthesis of fused nitrogen containing heterocycles as anticancer agents

Facile synthesis of fused nitrogen containing heterocycles as anticancer agents

synthesis of pyrazolopyridopyrimidines were based on utilizing amino pyrazole or amino pyrimidine as starting materials with different catalysts[5,13]. Aiming to synthesize these important candidates with low cost starting materials and facile tools, we have prepared different fused derivatives via simple pyrazole (5-methyl-2,4-dihydro-3H-pyrazol-3-one) as starting material. Facile conversion of the pyrazolopyridines into pyrazolopyridopyrimidines has been reported. As for the multifocal nature of liver Carcinoma, the chemotherapy is the main choice for the liver cancer patient's treatment, so developing new therapeutic agents becomes an urgent need for liver cancer patients. Encouraged by this information and continuation to our previous work[14,15]. We have prepared in this report the formation of different derivatives of Nitrogen containing heterocycles and have evaluated their efficiency as an antihepatocellular Carcinoma.

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Novel catalysts for the hydroxymethylation of allyl alcohol : a convenient synthetic route to 1, 4 butanediol

Novel catalysts for the hydroxymethylation of allyl alcohol : a convenient synthetic route to 1, 4 butanediol

Dynamic metal-ligand interactions offer one approach to supramolecular design, 2 and these binding motifs are principally represented by axial coordination of a nitrogen-donor to the metal centre of a metalloporphyrin. This approach has been applied for the construction of coordination polymers and molecular squares, 3 and the interactions are found to be stable under conditions relevant to catalysis. 4 By the templation of zinc(II) salphen on pyridylphosphines, Kleij et al. have illustrated that the coordination geometry of the encapsulated assembly is determined by the configuration of the latter. 5 Thus, sterically demanding tri(m-pyridyl)phosphine-based supramolecular structures were found to be mono-coordinated in several transition metal complexes. Conversely, the rhodium(I) complexes of tri(p-pyridyl)phosphine-based supramolecular structures displayed behaviour typical of chelated rhodium(I) species in the hydroformylation of 1-octene. The activity of these catalysts appeared to be regulated by the substitution pattern of the meso-phenyl functionalities. This coordinative pattern was later advanced by Reek et al. to create a library based on phosphite-modified zinc(II) porphyrins and nitrogen-containing phosphines, popularly termed SUPRAPhos. 6 The chelation behaviour of these assemblies in rhodium(I) species was confirmed both by high pressure NMR spectroscopy and complexation studies. The catalytic parameters of these complexes in the hydroformylation of styrene were shown to be highly dependent upon the structural units, but in all cases chelation was maintained under the operating conditions.

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Synthesis of nitrogen containing heterocycles via radical cyclisation

Synthesis of nitrogen containing heterocycles via radical cyclisation

The N-benzyl protected precursors (127-129) all gave N.M.R. spectra which were broad with individual signals and split, presumably due to restricted rotation around the amide bond. Conjugation between the nitrogen lone pair and the carbonyl leads to increased double bond character in the C-N bond and there was some degree o f restricted rotation about this bond at RT. The major rotamer in each case presumably arose from the corresponding (E) conformation due to the (Z) conformation being higher in energy. The ratio o f (E) to (Z) proved to be dependent on the relative size o f the substituents R|. The smaller the substituent R| the larger the amount of the (Z) conformation observed in the N.M.R. (table 19). The broadening o f the spectra was in agreement with those previously prepared and published.,27h) The yields o f the precursors were generally good and in line with literature values.

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Stierstorfer, Jörg
  

(2009):


	Advanced Energetic Materials Based on 5-Aminotetrazole: Synthesis, Characterization, Testing and Scale-up.


Dissertation, LMU München: Fakultät für Chemie und Pharmazie

Stierstorfer, Jörg (2009): Advanced Energetic Materials Based on 5-Aminotetrazole: Synthesis, Characterization, Testing and Scale-up. Dissertation, LMU München: Fakultät für Chemie und Pharmazie

Development of new high explosives - A never ending challenge! Ongoing worldwide research of new energetic materials for both, civilian and military applications are currently developing pyrotechnics with reduced smoke and new explosives and propellants with higher performance or enhanced insensitivity to thermal or shock insults. The introduction of a new compound into technical application is even hard (or harder) as commercial launch of new pharmaceuticals. Numerous requirements must be fulfilled, which are not conceivable when designing and synthesizing new energetic materials. One approach is the use of high nitrogen or all-nitrogen compounds. Up to date, there is no example of a homo-polyatomic nitrogen compound which could be used as HEDM, since neither thermodynamic nor kinetic stabilization with respect to decomposition into N 2 has been achieved. Therefore, experimental investigations [24] are

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