Heterocyclic systems

Ebook "Structure, bonding and reactivity of heterocyclic compounds" focuses on the aspects of structure, bonding and reactivity of heterocyclic systems. It aims at presenting a series of different state-of-the-art methods and concepts available in quantum mechanics and theoretical chemistry to probe these different important aspects of heterocyclic compounds.

199p tudohanhtau1006 29-03-2024 1 1   Download

Ebook "Heterocyclic supramolecules II (Topics in heterocyclic chemistry, Volume 18)" which is a continuation of Supramolecular Chemistry I, is a review of recent studies on intermolecular interactions connecting (and occasionally repelling) the molecules together with a few individual topics including formation, structure, and function of crystalline-state host-guest supramolecular systems and intelligent supramolecular nano assemblies and highly stereoselective 1,3-dipolar cycloaddition catalyzed by supramolecular complex.

167p manmanthanhla0201 26-02-2024 2 1   Download

In ebook "High- and low-valent tris-N-heterocyclic carbene iron complexes: A study of molecular and electronic structure" high valent iron nitride and oxo species have been proposed as key intermediates in many bio-catalytic transformations, but until now these species have proven exceedingly challenging to isolate and study. Iron complexes in high oxidation states can thus serve as models for iron-containing enzymes to help us understand biological systems or aid our development of more efficient industrial catalysts.

145p nhanphanguyet 28-01-2024 8 2   Download

In continuation of our interest in identifying new α-glucosidase inhibitors with potential to become antidiabetic drugs, this work focuses on the study of 4-(dimethylaminoalkyl)piperazine-1-carbodithioate derivatives as α-glucosidase inhibitors. The eight heterocyclic piperazine-dithiocarbamate complexes studied in this work contain a variety of substitutions on their benzene ring exhibiting potent, noncompetitive inhibition of α-glucosidase.

9p lyhuyenthu 31-01-2023 9 2   Download

This review article represents a survey covering the synthetic strategies leading to 5-membered heterocycles. The reactions are subdivided into groups that cover the synthetic methods of those heterocycles, i.e. pyrroles, furans, thiophenes, pyrazoles, isoxazoles, thiazoles, and others, utilizing benzoylacetonitriles as starting precursor from 1985 up to the present. The reactions are subdivided into groups that cover the synthetic methods for those heterocycles from benzoylacetonitriles.

27p langthannam 29-12-2021 8 0   Download

Novel benzimidazolium salts having N-benzyl or N-(4-substitutedbenzyl) groups were synthesized and their microwave-promoted catalytic activity for the Suzuki–Miyaura cross-coupling reaction were determined using in situ formed palladium(0) nanoparticles (PdNPs) from a catalytic system consisting of Pd(OAc) 2 /K2CO3 in DMF/H2 O. PdNPs were characterized by X-ray diffraction (XRD) pattern and particle size of in situ generated PdNPs from the Pd(111) plane was determined to be of diameter 19.6 nm by the Debye–Scherrer equation.

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The current review summarizes the known routes to different azoles linked directly to imidazole. This review is divided into classes based on the type of azoles connected to an imidazole ring. Some medical applications are mentioned. As a continuation of our very recently published review article concerning the synthesis of biologically active heterocyclic systems, 20−23 we prepared this review to present for the reader a survey of the literature on different azoles linked directly with an imidazole nucleus. Some of the medicinal applications are also mentioned.

27p langthannam 29-12-2021 8 0   Download

A new, less expensive, solvent-free procedure was developed for the synthesis of some new derivatives of various fused heterocyclic ring systems, namely azolopyridazine, azolotriazine, azinotriazine, thienopyridine, and pyrazolopyridine. The structures of the products prepared were established by their spectral data and elemental analyses. Eight compounds were evaluated for their in vitro antimicrobial activity. Some of the tested compounds exhibited moderate to significant antibacterial and antifungal activities.

15p langthannam 29-12-2021 10 0   Download

A series of asymmetrical substituted tetrahydropyrimidinium salts and different kinds of bridged bistetrahydropyrimidinium salts were prepared through the quaterization of tetrahydropyrimidine or the dehydrogenation of hexahydropyrimidine. They were characterized and used as NHC precursors in the palladium catalyzed Buchwald– Hartwig amination reaction.

9p langthannam 29-12-2021 8 1   Download

In this account the authors’ latest results in C–C coupling catalysis are reviewed. First, an efficient catalytic system for the Kumada–Tamao–Corriu coupling reaction based on NHC-phosphine (NHC = N-heterocyclic carbene) nickel complexes is presented. Then the use of palladium complexes of chiral ferrocenyl NHC-phosphines in the asymmetric Suzuki–Miyaura coupling reaction is reported. High catalytic activities and moderate enantioselectivities (ee up to 46%) were obtained.

13p langthannam 29-12-2021 9 0   Download

In this study, a series of benzimidazole-piperidine derivatives were synthesized with the objective of developing potent antinociceptive agents. Some 2-(4-substituted-phenyl)-1-[2-(piperidin-1-yl)ethyl]-1H-benzimidazole derivatives were obtained by microwave-supported reaction of an appropriate 2-(4-substituted-phenyl)-1H-benzimidazole with 2-(piperidine-1-yl)ethyl chloride. The chemical structures of the compounds were elucidated by FT-IR, 1H NMR, 13C NMR, and HRMS spectral data. Antinociceptive activity was assessed by conducting hot-plate, paw-pressure, and formalin tests.

13p tudichquannguyet 29-11-2021 9 1   Download

The tetrahydropyridine (THP) ring system has received considerable focus due to its excellent ability to act as a pharmacophore. It is recognized as a major constituent in natural alkaloids. THP derivatives have been reported for a diverse range of biological activities. Recent synthetic works contain syntheses of monosubstituted, disubstituted, trisubstituted, highly functionalized, and condensed structures. In this review, we summarize the recent literature dealing with the bioactive nature of this important heterocycle.

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Many benzimidazole salts bearing a 3-phenylpropyl substituent (1a–1h) were synthesized and their structures were identified by 1H NMR, 13C NMR, and IR spectroscopic methods and elemental analysis. These N-heterocyclic carbene (NHC) precursors were used as a part of a catalytic system including Pd(OAc) 2 and the base in the Suzuki– Miyaura cross-coupling reaction under microwave irradiation. They were also used as catalysts in the cyclotrimerization of phenyl isocyanate to yield 1,3,5-triphenyl-1,3,5-triazinane-2,4,6-trione.

31p tudichquannguyet 29-11-2021 3 1   Download

The piperazine ring system is among the medicinally important nitrogen-containing heterocyclic ring systems and is exploited for the synthesis of various drug molecules. A number of FDA-approved anticancer drugs contain piperazine rings and thus it is considered as an attractive scaffold having extraordinary potential for the development of new anticancer agents. In recent decades there has been an alarming increase in the number of people suffering from cancerous diseases all over the world, which resulted in an extraordinary increase in research reports on new anticancer drug candidates.

23p tudichquannguyet 29-11-2021 9 1   Download

In this study, a series of cyclotriphosphazene derivatives containing a Schiff base (3a–3d) were synthesized by the reactions of hexachlorocyclotriphosphazene (1) with bis-aryl Schiff bases (2a–2d) having different terminal groups (H, F, Cl, and Br). The products (3a–3d) were characterized by elemental and mass analyses, FT-IR, and 1 H, 13 C, and 31P NMR spectroscopies. Furthermore, the structure of compound 3a was also determined by X-ray crystallography.

17p tudichquannguyet 29-11-2021 10 1   Download

The present review article aims to review the work reported on therapeutic potentials of oxazole scaffolds which are valuable for medical applications during new millennium.azole derivatives

24p vijiraiya2711 27-05-2020 8 1   Download

Chalcones are intent in the daily diet as a favorable chemotherapeutic compound; on the other hand thiophene moiety is present in a large number of bioactive molecules having diverse biological effciency.

8p vijiraiya2711 27-05-2020 9 1   Download

Mechano heterocyclic chemistry (MCH) is a recent quickly growing technique in the synthesis of het‑ erocycles and draws the attention of heterocyclic chemists towards the uses of grindstone technique in a solvent free green efficient synthesis of many heterocyclic systems.

7p vijiraiya2711 27-05-2020 10 1   Download

N fertilizers and high yielding varieties were major drivers of the enormous increase in rice productivity during the past 50 years. Despite increasing food production higher nitrogen use also contributed in environmental pollution and Increasing consciousness of conservation of environment and mitigation of climate change brought a major shift in cultivation practices of major crops towards organic agriculture. An important issue regarding the acceptance of organic agriculture is the question of productivity.

19p nguaconbaynhay5 16-05-2020 14 0   Download

The reaction of 6-amino-1,3-dimethylpyrimidine-2,4(1H,3H)-dione (1) as a binucleophile with primary aromatic or heterocyclic amines and formaldehyde or aromatic (heterocyclic) aldehydes in a molar ratio (1:1:2) gave the pyrimido[4,5-d]pyrimidin-2,4-dione ring systems 2–5. Treatment of 1 with diamines and formalin in molar ratio (2:1:4) gave the bis-pyrimido[4,5-d]pyrimidin-2,4-diones 6–8. Furthermore, substituted pyrimido[4,5-d]pyrimidin-2,4-diones with uracil derivative 11 or spiro indole 16 were synthesized.

7p kethamoi1 17-11-2019 16 1   Download