Annulated Heterocyclic Systems Research Articles

Friedländer reactions for novel annulated pyridotriazolothiazolopyridines: Synthetic approaches and antimicrobial evaluation

o-Aminoaldehyde 1 was employed as starting precursor for construction of some linear heterocyclic compounds. o-Aminoaldehyde 1 was permitted to undergo Friedländer reaction with some acyclic and cyclic methylene ketones giving the novel annulated heterocyclic systems 2-10. Moreover, the reactivity of o-aminoaldehyde 1 was examined toward some cyclic enamines and enols producing the corresponding annulated heterocyclic systems. The prepared compounds were investigated for their antimicrobial efficiency displaying different inhibition action toward the tested microorganisms. Based on analytical spectral and results, structures of the produced compounds were established.

Domino Reactions of Chromones with Heterocyclic Enamines

AbstractDomino reactions of heterocyclic enamines with chromone derivatives provides a convenient synthesis of a great variety of annulated heterocyclic ring systems. The course of the reaction depends on the type of substituent located at position 3 of the chromone. Reactions of 3-unsubstituted chromones, 3-nitrochromones, and 3-halochromones proceed by conjugate addition of the carbon atom of the enamine to carbon C-2 of the chromone, ring cleavage, and recyclization via the chromone carbonyl group. In the case of 3-formylchromes, 3-dichloroacetylchromone, 3-perfluoroalkanoylthiochromones, 3-(2-fluorobenzoyl)chromones, and 3-methoxalylchromones the final cyclization proceeds via the carbonyl group located outside the chromone moiety. The functional groups located at the carbonyl group at position 3 of the chromone allow for further synthetic transformations including additional ring closures.Contents1 Introduction2 3-Unsubstituted Chromones3 3-Nitrochromones4 3-Formylchromes5 3-Dichloroacetylchromone6 3-Perfluoroalkanoylthiochromones7 3-Methoxalylchromones8 3-(2-Fluorobenzoyl)chromones9 3-Halochromones10 Chromone-3-carboxylic Acids11 Conclusions

One-Pot Access to Diverse Functionalized Pyran Annulated Heterocyclic Systems Using SCMNPs@BPy-SO3H as a Novel Magnetic Nanocatalyst

The SCMNPs@BPy-SO3H catalyst was prepared and characterized using Fourier Transform Infrared Spectroscopy (FTIR), Thermogravimetric Analysis (TGA), Vibrating Sample Magnetometry (VSM), Energy Dispersive X-ray Spectroscopy (EDX), X-ray Diffraction (XRD), and Scanning Electron Microscopy (SEM). Afterwards, its capability was efficiently used to promote the one-pot, three-component synthesis of pyrano[2,3-c]pyrazole and 2-amino-3-cyano-pyrano[3,2-c]chromen-5(4H)-one derivatives. The strategy resulted in the desired products with excellent yields and short reaction times. The SCMNPs@BPy-SO3H catalyst was readily recovered using a permanent magnetic field and it was reused in six runs with a slight decrease in catalytic activity. Copyright © 2020 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Uric Acid as a Naturally Biodegradable and Reusable Catalyst for the Convenient and Eco-Safe Synthesis of Biologically Active Pyran Annulated Heterocyclic Systems

A naturally biodegradable, reusable, and eco-safe catalyst, i.e., uric acid was developed and exploited for the green, facile and economical one-pot synthesis of pyran annulated heterocyclic systems from starting materials. This method gives an insight into the credibility of pathway followed by the aforementioned green and reusable catalyst in aiding the heterocyclic compounds formation. High atom economy, cleaner reaction profile, simple column-free work up condition, shorter reaction times, high to excellent yields, eco-safe and high catalytic activity make this present procedure an interesting alternative to the multistep approaches.

Nitroacetonitrile as a versatile precursor in energetic materials synthesis.

Nitroacetonitrile is the simplest α-nitronitrile; it possesses a single central carbon attached to two strong electronegative, electron-withdrawing groups allowing extensive chemistry through the active methylene center. Free nitroacetonitrile has purification and stability issues, however stable salts of nitroacetonitrile possess the same reactivity as the free acid and are much more stable. Nitroacetonitrile serves as a versatile synthetic precursor in the formation of heterocyclic and polyfunctional aliphatic products and can allow for straightforward conversion to amino, acyl, and other functional groups. A main advantage of using nitroacetonitrile in the formation of heterocyclic-based energetics is its ability to add vicinal amino and nitro moieties onto fused ring structures, a common structural motif in insensitive energetic materials. In this minireview we discuss the preparation of nitroacetonitrile and its stable salts, as well as discuss the range of energetic materials this versatile precursor has found use in.

Quantum-Chemical Study of the Reaction Mechanism of 2-Mercaptobenzothiazole with Iodomethyl(dimethyl)phenylsilane in the Presence of Iodine

A quantum-chemical study of the reaction mechanism of 2-mercaptobenzothiazole with (iodomethyl)(dimethyl)phenylsilane in the presence of iodine was performed by the B3LYP/6-311G(d,p) method. Possible routes of formation of annulated heterocyclic systems were proposed. It was found the molecular iodine involved in the reaction has a decisive effect on the thermodynamic and kinetic characteristics of the cyclization process.

Green Synthesis of Dihydropyrimidine Annulated Heterocyclic Systems Catalyzed by Nanoporous Na+-Montmorillonite Perchloric Acid and Evaluation of Their Biological Activities

An efficient and environmentally benign method for the green one-pot synthesis of dihydrobenzoimidazolo pyrimidine derivatives has been developed by multi-component reaction of 2-aminobenzimidazole, ethyl acetoacetate or malononitrile and aromatic aldehydes using nanoporous Na+-montmorillonite perchloric acid as a novel heterogeneous solid acid catalyst. The catalyst was easily prepared and characterized by X-ray powder diffraction, FTIR, SEM-EDX, TGA, BET, nitrogen adsorption–desorption measurements, pH analysis, and Hammett acidity function. Also, the antibacterial activity of synthesized compounds was evaluated and some products showed good activity. Availability and low cost of the reagent, ease of preparation and reusability of the catalyst, short reaction times, high yields of the products, operational simplicity, and solvent-free reaction conditions are some of the main advantages of this novel synthetic method.

K2CO3: A Mild and Efficient Catalyst for the Synthesis of Pyran Annulated Heterocyclic Systems by Grinding Method Under Solvent-Free Conditions

Abstract The potassium carbonate was applied as a green and efficient catalyst for the one-pot synthesis of pyran annulated heterocyclic systems, via the condensation between aromatic aldehydes, malononitrile and dimedone/1-naphtole by a grinding method at room temperature and solvent-free conditions. Short reaction times, environmentally friendly procedure and excellent yields are the main advantages of this procedure which makes it more economic than other environmentally synthetic methods.

Synthesis of annulated heterocyclic systems based on 2-mercaptoimidazoline and α-iodo ketones

The reaction of 2-mercaptoimidazoline with 1-iodopropan-2-one or 1,3-diiodopropan-2-one in the absence or in presence of iodine allowed to synthesize new types of annulated heterocyclic systems in one preparative step.

An Efficient Eco-Friendly Synthesis of Pyran Annulated Heterocyclic Systems under Conventional Heating and Microwave Irradiation in Solvent-Free Conditions

ABSTRACT1,4-Diazabicyclo[2.2.2]octane (DABCO) has been used as an efficient and reusable solid base catalyst for the rapid and green synthesis of pyran annulated heterocyclic ring systems by the condensation reaction of various activated CH-acids and tetracyanoethylene under conventional heating and microwave irradiation in solvent-free conditions. Excellent yield, very short reaction time (2–5 min), operatinal simplity, easy work-up procedure, avoidance of hazardous or toxic catalysts, and organic solvents are the main advantages of this green methodology which makes it more economic than the other conventional methods.

Microwave-Assisted and L-proline Catalysed Domino Cyclisation in an Aqueous Medium: A Rapid, Highly Efficient and Green Synthesis of Benzo[a]Phenazine Annulated Heterocycles

A highly efficient one-pot, two-step microwave-assisted procedure was applied for the rapid and green synthesis of benzo[a]phenazine annulated heterocyclic ring systems from the three- or four-component condensation reactions of 2-hydroxynaphthalene-1,4-dione, o-phenylenediamine, aromatic aldehydes and 1,3-indandione using L-proline as a bifunctional organocatalyst in water. This new procedure has a number of advantages such as high yields, very short reaction times, operational simplicity, simple work-up procedures and avoidance of hazardous or toxic catalysts and organic solvents. Moreover, the catalyst can be recovered and reused several times without much loss of its performance.

ChemInform Abstract: Titanium Dioxide Nanoparticles as Efficient Catalyst for the Synthesis of Pyran′s Annulated Heterocyclic Systems via Three‐Component Reaction.

AbstractThe catalyst can be reused for six times without significant decrease in efficiency.

γ-Alumina Catalyzed Green Synthesis of Pyran’s Annulated Heterocyclic Systems via Three-Component Reaction

γ-Alumina was found as a new efficient heterogeneous catalyst for the synthesis of pyran’s annulated heterocyclic systems. Three-component reaction of various aromatic aldehydes, malononitrile and cyclic CH-acids in the presence of γ-alumina in H2O as a green solvent at 50 °C gave pyran derivatives in high yields. γ-Alumina has some advantages such as cheap, available and recyclable.

ChemInform Abstract: Synthesis of Annulated Heterocyclic Systems Based on 4‐CF3‐ or 4‐CHF2‐3‐cyano‐(1H)‐pyridine‐2‐thiones.

Abstract3‐Cyano‐4‐difluoro‐ and trifluoromethylpyridine‐2(1H)‐thiones are synthesized by a simple and convenient method and used for the synthesis of a number of annulated heterocyclic systems.

Full Kinetics and a Mechanistic Investigation of the Synthesis of Tetrahydrobenzo[ b]pyrans in the Presence of Sodium Acetate as a Catalyst by a One-pot Three-component Reaction

Sodium acetate effectively catalyzes the three component reaction between 4-nitrobenzaldehyde, malononitrile and dimedone for the formation of corresponding pyran annulated heterocyclic systems. This method offers the advantages of proceeding in neutral and mild environmental conditions, lack of toxicity, short reaction time, giving high to excellent yields of the products and simple work-up. Moreover, for the first time, an investigation of the kinetics and mechanism was made for the reaction between 4-nitrobenzaldehyde 2, malononitrile 3 and dimedone 1 compounds in the presence of sodium acetate as a catalyst. For determining the kinetics parameters of the reactions, they were monitored using UV/Vis spectrophotometery. The second order rate constant (k1) was automatically calculated by the standard equations contained within the program. In the studied temperature range, the second order rate constant depended (Lnk1, Lnk1/T) on reciprocal temperature was in good consistency with Arrhenius and Eyring equations, respectively. This data provided the suitable plots for calculating the activation energy and parameters (Ea, ΔG#, ΔS# and ΔH#) of the reaction. Furthermore, from studying the effect of solvent, concentration and catalyst on the reaction mechanism, useful information was obtained. The results showed that the first step of the reaction mechanism is a rate determining step (RDS). The mechanism which we proposed was confirmed in accordance with experimental data form UV/Vis experiment and also the steady state assumption. Keywords: Dimedone, tetrahydrobenzo[b]pyran, Sodium acetate, 4-nitrobenzaldehyde, malononitrile, Kinetics and Mechanistic Investigation, UV/Vis spectrophotometery.

Synthesis of annulated heterocyclic systems based on 4-CF3- or 4-CHF2-3-cyano-(1H)-pyridine-2-thiones

A simple and convenient preparative method for the synthesis of 3-cyano-4-difluoro- and -trifluoromethylpyridine-2(1H)-thiones was developed. During studies of synthetic potential of these compounds, approaches to the synthesis of a number of annulated heterocyclic systems were suggested.

TiO2 and TiO2 nanoparticles as efficient and recoverable catalysts for the synthesis of pyran annulated heterocyclic systems

TiO2 catalyzed reactions between various activated CH-acids and tetracyanoethylene are described. This reaction affords the corresponding pyran annulated heterocyclic systems in high yields at room temperature in 3 h. The work-up procedure is very simple, and the products do not require further purification. The catalysts can be recycled and reused several times without observable loss of performance.

Pyrimidines과 pyrimidine의 헤테로고리의 합성

Imine 화합물 1을 hydrazine hydrate와 같은 nitrogenous 시약과 반응시켜서 치환된 pyrimidines 화합물을 합성하였다. 얻어진 화합물 2를 다양한 반응조건, 즉 propionic acid, formic acid, ethyl chloroformate, acdetic anhydride, carbon disulphide, cyanogene bromide, triflauroacetic acid 및 ethyl chloroacetate와 반응시켜서 대응하는 화합물을 좋은 수율로 얻었으며, 반응은 Dimroth-type 자리옮김 반응을 통하여 진행되었다. We have involved the imine compound 1 in condensations with various nitrogenous reagents including hydrazine hydrate to construct differently substituted pyrimidines. One of the pyrimidines so obtained was further subjected to interactions with different reagents such as propionic acid, formic acid, ethyl chloroformate, acdetic anhydride, carbon disulphide, cyanogene bromide, triflauroacetic acid and ethyl chloroacetate which resulted in the formation of annulated heterocyclic systems as pairs of isomers in most cases as a result of Dimroth-type rearrangement.

One‐pot synthesis of functionalized fused 4H‐pyran systems

Abstract magnified image Cyclohexyl isocyanides react with dialkyl acetylenedicarboxylates in the presence of CH‐acids such as cyclohexane‐1,3‐dione or N,N′‐dimethylbarbituric acid in one‐pot to afford 4H‐pyran annulated heterocyclic systems in fairly high yields. J. Heterocyclic Chem., (2010)

ChemInform Abstract: Pyridine‐Functionalized MCM‐41 as an Efficient and Recoverable Catalyst for the Synthesis of Pyran Annulated Heterocyclic Systems.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.