Aqueous N-Heterocyclization of Primary Amines and Hydrazines with Dihalides: Microwave-Assisted Syntheses of N-Azacycloalkanes, Isoindole, Pyrazole, Pyrazolidine, and Phthalazine Derivatives

Construction of N-Aryl-Substituted Pyrrolidines by Successive Reductive Amination of Diketones via Transfer Hydrogenation

N-aryl-substituted pyrrolidines are important moieties widely found in bioactive substances and drugs. Herein, we present a practical reductive amination of diketones with anilines for the synthesis of N-aryl-substituted pyrrolidines in good to excellent yields. In this process, the N-aryl-substituted pyrrolidines were furnished via successive reductive amination of diketones via iridium-catalyzed transfer hydrogenation. The scale-up performance, water as a solvent, simple operation, as well as derivation of drug molecules showcased the potential application in organic synthesis.

Synthesis, docking and biological evaluation of purine-5-N-isosteresas anti-inflammatory agents

An operationally simple one-pot three-component and convenient synthesis method for a series of diverse purine analogues of 5-amino-7-(substituted)-N-(4-sulfamoylphenyl)-4,7-dihydro-[1,2,4]-triazolo[1,5-a][1,3,5]triazine-2-carboxamide derivatives generated in situ via the reaction of 2-hydrazinyl-N-(4-sulfamoylphenyl)-2-thioxoacetamide, cyanoguanidine and a variety of aldehydes was achieved under green conditions. This experiment was conducted to evaluate the anti-inflammatory effect of the newly synthesized compounds using indomethacin as a reference medication; all compounds were tested for in vitro anti-inflammatory activity using the inhibition of albumin denaturation, RBC hemolysis technique and COX inhibition assay. The results showed that all evaluated compounds exhibited significant in vitro anti-inflammatory efficacy leading to excellently effective RBC membrane stabilization, inhibition of protein denaturation, and inhibition of COX enzymes when compared to those of indomethacin. At concentrations of 50, 100, 200, and 300 μg ml-1, these compounds decreased COX-1 and COX-2 activities more than indomethacin and have IC50 values in the range of 40.04-87.29 μg ml-1 for COX-1 and 27.76-42.3 μg ml-1 for COX-2 while indomethacin showed IC50 = 91.57 for COX-1 and 42.66 μg ml-1 for COX-2. The anti-inflammatory findings show the need for more investigation to define the properties underlying the evaluated compounds' anti-inflammatory abilities. The enzyme cyclooxygenase-2 (COX 2) (PDB ID: 5IKT) was docked with ten synthetic substances. With docking scores (S) of -8.82, -7.82, and -7.76 kcal mol-1, 7-furan triazolo-triazine (4), 7-(2-hydroxy phenyl) triazolo-triazine (11), and 7-(4-dimethylamino phenyl) triazolo-triazine (12) had the greatest binding affinities, respectively. Therefore, these substances have COX-2 (PDB ID: 5IKT) inhibitory capabilities and hence may be investigated for COX 2 targeting development. Furthermore, both the top-ranked compounds (4 and 11) and the standard indomethacin were subjected to DFT analysis. The HOMO - LUMO energy difference (ΔE) of the mentioned compounds was found to be less than that of indomethacin.

Synthesis and in Silico Studies of Some New 1,2,3-Triazolyltetrazole Bearing Indazole Derivatives as Potent Antimicrobial Agents

1,2,3-Triazole and tetrazole derivatives bearing pyrrolidines are found to exhibit notable biological activity and have become useful scaffolds in medicinal chemistry for application in lead discovery and optimization. Novel indazole bearing 1,2,3-triazolyltetrazoles were designed as potential antimicrobial candidates. The structure of duel heterocyclics was validated by a spectroscopic technique of infrared (IR), nuclear magnetic resonance (1 H and 13 C NMR), and mass spectral data. Compounds 4b, 4c, 4d, and 4h were found to have a stronger antibacterial effect against Gram-positive (S. aureus, B. subtilis, M. Luteus) and Gram-negative (E. coli, P. aeruginosa) microorganisms with MICs ranging from 5±0.03-18±0.02 μM, respectively. Moreover, scaffolds 4a, 4h showed potent antifungal activity against A. flavus, M. gypsuem strains with MIC values of 10±0.02, 11±0.01 μM, which are similar activity that of the standard Itraconazole (MIC=8±0.02, 10±0.01 μM). The binding mode for compound 4 inside the catalytic pocket of S. aureus complexed with nicotinamide adenine dinucleotide phosphate and trimethoprim and produced a network of hydrophobic and hydrophilic interactions (3FRE). From in silico results, 4b demonstrated highly stable hydrogen binding amino acids Leu62(X) [N18…O, 2.47 Å], Arg44(X) [N17…N, 3.11 Å], Thr96(X) [N10…OG1, 3.05 Å], Gly94(X) [F7…N, 2.82 Å], and Gly43(X) [F7…N, 2.90 Å], which are plays a crucial role in ensuring efficient binding of the ligand in a crystal structure of antibacterial receptor. Furthermore, the physicochemical and ADME filtration molecular properties, estimation of toxicity, and bioactivity scores of these novel scaffolds were evaluated by using SwissADME and ADMETlab2.0 online protocols. Thus, the significant antimicrobial activity of indazole linked to duel heterocyclic compounds can be used for development of new antimicrobial agents with further modifications.

In-silico investigation of 4-nitro-N-1H-pyrazol-3-ylbenzamide towards its potential use against SARS-CoV-2: a DFT, molecular docking and molecular dynamics study

In the present research work, we report the synthesis and characterization of novel pyrazole derivative obtained by the condensation reaction of 4-nitro benzaldehyde group with one equivalent of the 2-amino pyrazole yielding 4-nitro-N-1H-pyrazol-3-ylbenzamide with high yield. The two symmetry-independent molecules (molecule A and molecule B) differ about the central C-N bond, with the dihedral angles between the pyrazole ring system and the nitrobenzene ring being 13.90° and 18.64°, respectively. By optimizing the symmetry-independent dimer molecules, the rotational barrier between the conformers is found to be within the 2.5-5.5 kcal/mol range. QTAIM and RDG based NCI isosurface revealed the presence of strong N-H…N and C-H…O hydrogen bonds which stabilize the two independent centrosymmetric inversion-related dimers. Further, weak and short directional interactions such as C-H…N, H…H and C-H…π were also analyzed systematically using various topological parameters. The compound is found to adhere to the Lipinski's rule of five and exhibit good pharmacokinetic properties. The results of molecular docking studies performed against SARS-CoV-2 virus main protease (PDB IDs: 6LU7, 6W9C and 6WQF) revealed that the compound showed better docking scores. Molecular docking studies verified the inhibition activity of the synthesized novel compound. Finally, the binding free energy and contributed energies were calculated using MM-GBSA method. The 6LU7-ligand complex showed highest binding free energy and among all other interactions, the contributions of the covalent binding and van der Waals energy are found to be significant.Communicated by Ramaswamy H. Sarma.

Inherent efficacies of pyrazole-based derivatives for cancer therapy: the interface between experiment and in silico

There has been an increasing trend in the design of novel pyrazole derivatives for desired biological applications. For a cost-effective strategy, scientists have implemented various computational drug design tools to go hand in hand with experiments for the design and discovery of potentially effective pyrazole-based therapeutics. This review highlights the milestones of pyrazole-containing inhibitors and the use of molecular modeling techniques in conjunction with experimental studies to provide a view of the binding mechanism of these compounds. The review focuses on the established targets that play a key role in cancer therapy, including proteins involved in tubulin polymerization, carbonic anhydrase and tyrosine kinase. Overall, using both experimental and computational methods in drug design represents a promising approach to cancer therapy.

Antiproliferative Activity of New Pyrazole-4-sulfonamide Derivatives: Synthesis and Biological Evaluation

Pyrazole and sulfonamide constitute an important class of drugs, with several types of pharmacological agents. Facile synthesis of two new series of 3,5-dimethyl-1H-pyrazole-4-sulfonamide and 1,3,5-trimethyl-1H-pyrazole-4-sulfonamide derivatives was designed and synthesized. These pyrazole-4-sulfonamide derivatives are characterized by Fourier transform infrared (FT-IR), ¹H NMR, ¹³C NMR, and elemental analysis, and their biological evolution data are presented. This paved way for the development of new pyrazole-4-sulfonamide derivatives. These compounds are tested for their in vitro antiproliferative activity against U937 cells by the CellTiter-Glo Luminescent cell viability assay using Mitomycin C. Cytotoxicity detection is based on the measurement of LDH activity, while these compounds did not exhibit cytotoxic activity on these cells. Half maximal inhibitory concentration (IC₅₀) was calculated by Graph Pad Prism software for each dose. Their structure-activity relationships were obtained and discussed.

Intramolecular Heterocyclization/Fluoromethylthiolation of Alkynes Enabled by a Multicomponent Reagent System

The BnSR_f (R_f = CF₂H or CF₃)/mCPBA/Tf₂O system was found to be an effective multicomponent reagent system for the one-pot synthesis of di/trifluoromethylthiolated heterocycles from alkynes. The reaction was postulated to proceed via a cascade sequence involving the oxidation of BnSR_f by mCPBA, activation of the in situ-generated sulfoxide by Tf₂O, and intramolecular cyclization/fluoromethylthiolation of the alkyne substrates enabled by the formed electrophilic sulfonium salt to give di/trifluoromethylthiolated heterocycles.

Synthetic Approaches, Biological Activities, and Structure-Activity Relationship of Pyrazolines and Related Derivatives

It has been established that pyrazolines and their analogs are pharmacologically active scaffolds. The pyrazoline moiety is present in several marketed molecules with a wide range of uses, which has established its importance in pharmaceutical and agricultural sectors, as well as in industry. Due to its broad-spectrum utility, scientists are continuously captivated by pyrazolines and their derivatives to study their chemistry. Pyrazolines or their analogs can be prepared by several synthesis strategies, and the focus will always be on new greener and more economical ways for their synthesis. Among these methods, chalcones, hydrazines, diazo compounds, and hydrazones are most commonly applied under different reaction conditions for the synthesis of pyrazoline and its analogs. However, there is scope for other molecules such as Huisgen zwitterions, different metal catalysts, and nitrile imine to be used as starting reagents. The present article consists of recently reported synthetic protocols, pharmacological activities, and the structure-activity relationship of pyrazoline and its derivatives, which will be very useful to researchers.

Pyrazole and pyrazoline derivatives as antimalarial agents: A key review

Malaria poses a severe public health risk and a significant economic burden in disease-endemic countries. One of the most severe issues in malaria control is the development of drug resistance in malaria parasites. The standard treatment for malaria is artemisinin-combination therapy (ACT). Nevertheless, the Plasmodium parasite's extensive resistance to prior drugs and reduced ACT efficiency necessitates novel drug discovery. The progress in discovering novel, affordable, and effective antimalarial agents is significant in combating drug resistance, and the hybrid drug concept can be used to covalently link two or more active pharmacophores that may act on multiple targets. Pyrazole and pyrazoline derivatives are considered pharmacologically necessary active heterocyclic scaffolds that possess almost all types of pharmacological activities. This review summarized recent progress in antimalarial activities of synthesized pyrazole and pyrazoline derivatives. The studies published since 2000 are included in this systematic review. This review is anticipated to be beneficial for future study and new ideas in searching for rational development strategies for more effective pyrazole and pyrazoline derivatives as antimalarial drugs.

Recent Advances in Synthetic Routes to Azacycles

A heterocycle is an important structural scaffold of many organic compounds found in pharmaceuticals, materials, agrochemicals, and biological processes. Azacycles are one of the most common motifs of a heterocycle and have a variety of applications, including in pharmaceuticals. Therefore, azacycles have received significant attention from scientists and a variety of methods of synthesizing azacycles have been developed because their efficient synthesis plays a vital role in the production of many useful compounds. In this review, we summarize recent approaches to preparing azacycles via different methods as well as describe plausible reaction mechanisms.

Formation of nitrogen-containing six-membered heterocycles on steroidal ring system: A review

Steroidal heterocyclic compounds constitute interesting and promising scaffolds for drug discovery as they have displayed diverse chemical reactivity and several types of biological activities. This study is a concise report on the most recent advancements in the chemistry of the steroid skeleton, including reactions at the A, B, and D ring systems. The modern synthetic methods for the steroidal nitrogen-containing six-membered heterocyclic derivatives from 3-keto-, 6-keto-, 17-keto-, and 20-keto-steroids, as well as 2-Aldo-, 4-Aldo-, 6-Aldo-, and 16-Aldo-steroids, are discussed. However, some other methods for the synthesis of steroidal N-containing 6-membered heterocyclic derivatives are also included. These compounds have shown therapeutic potential as cytotoxic agents against various cell lines and have also shown antiproliferative, anti-inflammatory, and antioxidant activities. Therefore, they could be used as prospective candidates for the development of various medications. This paper not only describes synthetic details involved in creating N-containing 6-membered heterocyclic steroid derivatives, but also provides a brief overview of the medicinal applications of these compounds. This information will be highly useful for the medicinal chemists conducting research in this field.

1,3 Dipolar Cycloaddition of Münchnones: Factors behind the Regioselectivity

The 1,3 dipolar cycloaddition reactions of münchnones and alkenes provide an expedite synthetic way to substituted pyrroles, an exceedingly important structural motif in the pharmaceutical and material science fields of research. The factors governing their regioselectivity rationalization are not well understood. Using several approaches, we investigate a set of 14 reactions (featuring two münchnones, 12 different alkenes, and two alkynes). The Natural Bond Theory and the Non-Covalent Interaction Index analyses of the noncovalent interaction energies fail to predict the experimental major regioisomer. Employing global cDFT descriptors or local ones such as the Fukui function and dual descriptor yields similarly inaccurate predictions. Only the local softness pairing, within Pearson's Hard and Soft Acids and Bases principle, constitutes a reliable predictor for the major reaction product. By taking into account an estimator for the steric effects, the correct regioisomer is predicted. Steric effects play a major role in driving the regioselectivity, as was corroborated by energy decomposition analysis of the transition states.

Recent Advances in N-Heterocyclic Small Molecules for Synthesis and Application in Direct Fluorescence Cell Imaging

Nitrogen-containing heterocycles are ubiquitous in natural products and drugs. Various organic small molecules with nitrogen-containing heterocycles, such as nitrogen-containing boron compounds, cyanine, pyridine derivatives, indole derivatives, quinoline derivatives, maleimide derivatives, etc., have unique biological features, which could be applied in various biological fields, including biological imaging. Fluorescence cell imaging is a significant and effective imaging modality in biological imaging. This review focuses on the synthesis and applications in direct fluorescence cell imaging of N-heterocyclic organic small molecules in the last five years, to provide useful information and enlightenment for researchers in this field.

2-[2-(Diphenylphosphoryl)phenyl]-1H-perimidine

In this paper, we report the crystal structure of 2-[2-(diphenylphosphoryl)phenyl]-1H-perimidine (L1) obtained from the ring closure reaction of 1,8-diaminonaphthalene and 2-(diphenylphosphino)benzaldehyde, followed by the dehydrogenation reaction with sodium metabisulfite (Na2S2O5). L1 was characterised using 1H, 13C & 31P NMR, FT-IR and X-ray single structure analyses.

Synthetic Imidazopyridine-Based Derivatives as Potential Inhibitors against Multi-Drug Resistant Bacterial Infections: A Review

Fused pyridines are reported to display various pharmacological activities, such as antipyretic, analgesic, antiprotozoal, antibacterial, antitumor, antifungal, anti-inflammatory, and antiapoptotic. They are widely used in the field of medicinal chemistry. Imidazopyridines (IZPs) are crucial classes of fused heterocycles that are expansively reported on in the literature. Evidence suggests that IZPs, as fused scaffolds, possess more diverse profiles than individual imidazole and pyridine moieties. Bacterial infections and antibacterial resistance are ever-growing risks in the 21st century. Only one IZP, i.e., rifaximin, is available on the market as an antibiotic. In this review, the authors highlight strategies for preparing other IZPs. A particular focus is on the antibacterial profile and structure-activity relationship (SAR) of various synthesized IZP derivatives. This research provides a foundation for the tuning of available compounds to create novel, potent antibacterial agents with fewer side effects.

Pyrazole Scaffolds: Centrality in Anti-Inflammatory and Antiviral Drug Design

BACKGROUND

Pyrazole is a component of a diversity of bioactive heterocyclic congeners with a broad-spectrum range of biological and pharmacological uses. Designing novel pyrazole and its analogues, revealing new routes for synthesizing this nucleus, exploring various potencies of that heterocycles, and looking for possible applications of pyrazoles are all becoming more important due to their numerous potential applications.

OBJECTIVES

Pyrazole scaffolds have been proven to be successful as anti-viral and anti-inflammatory therapeutic against multiple targets like HSV-1, NNRTI, H1N1, CoX-1, and CoX-2. Due to this miscellany in the biotic area, this moiety has engrossed the consideration of many scientists to study chemistry and pharmacological profile.

RESULTS

The review encompasses pyrazole having various scaffolds with multiple biological activities and attempts have also been made to correlate their structure-activity relationship. Multiple pyrazole correspondents have been synthesized as lead molecules and performed valuation for their actions.

CONCLUSION

The incorporation of pyrazole with other pharmacophores in the molecule might lead to novel potent therapeutic agents that will further help in designing potent lead molecules.

Facile tin(II)-catalyzed synthesis of N-heterocycles from dicarboxylic acids and arylamines

A novel efficient transformation reaction of dicarboxylic acids into N-aryl-substituted azacycles is described. In this synthetic procedure, both catalytic SnCl₂ and phenylsilane were used as crucial reagents for reaction of arylamines with dicarboxylic acids to produce the desired azacycles. Using this SnCl₂-catalyzed synthetic method, various N-aryl-substituted azacycles were successfully prepared from arylamines with dicarboxylic acids in high yield. This practical synthetic method using catalytic SnCl₂ can provide a useful approach for preparation of the desired azacycle products from many available dicarboxylic acid starting materials.

A Molecular Insight into Pyrazole Congeners as Antimicrobial, Anticancer, and Antimalarial Agents

BACKGROUND

Pyrazole is a bioactive heterocyclic congener found in a wide range of biological and pharmacological applications. Due to their multiple prospective uses, developing innovative pyrazoles and analogues, disclosing revolutionary ways for synthesizing this nucleus, investigating diverse potencies of that heterocycle, and seeking for possible applications of pyrazoles are all growing more significant Objectives: Pyrazole scaffolds have been proven to be successful as antimicrobial, anticancer, antimalarial therapeutic against multiple targets like DNA gyrase, topoisomerase IV, Hsp90, and several kinase enzymes. Its moiety has absorbed the attention of many scientists to research chemical and pharmacological profile due to this miscellany in the biotic region.

RESULTS

The review covers pyrazole scaffolds with a variety of biological functions, as well as attempts to connect the structure-activity relationship. Multiple pyrazole analogues have been produced as lead compounds, and their activities have been evaluated.

CONCLUSION

The combination of pyrazole with other pharmacophores in a molecule might lead to novel potent therapeutic medicines, which could aid in the development of potent lead compounds.

Improving the yield of graphene oxide-catalysed N-heterocyclization of amines through fed batch mode

The use of graphene oxide, a metal-free, heterogeneous carbocatalyst for a facile, efficient, and simple protocol for N-heterocyclization of aromatic amines with dihaloalkane to give azacycloalkanes and isolindolines in fed batch strategy was studied.

Design, synthesis, and molecular docking of cysteine-based sulphonamide derivatives as antimicrobial agents

Background and purpose:

The preponderance of microbial infections remains a global challenge. In the present study, synthesis of novel cysteine-based antimicrobial agents and their biological evaluation is reported.

Experimental approach:

The reaction of p-toluenesulphonyl chloride with cysteine afforded 2-{[(4-methylphenyl)sulphonyl]amino}-3-sulphanylpropanoic acid (3) which was acetylated based on Lumiere-Barbier method using acetic anhydride. The ammonolysis of the acetylated compound (4) gave the carboxamide derivative (5) which reacted with aniline, aminopyridine and diaminopyrimidine via nickel catalyzed Buchwald-Hartwig amidation reaction to afford compounds 6a, 6b, and 6c, respectively. The compounds were characterized using FTIR, ¹H-NMR, ¹³C-NMR, and elemental analysis. The in vitro antimicrobial activities were determined. Their physicochemical properties were generated in silico and the molecular docking studied bacterial and fungal infections.

Findings/Results:

Compounds 4, 6b, and 6c exhibited excellent in vitro antibacterial activities while compound 4 had the best antifungal activities. From the in silico antimicrobial results, compound 3 had a better binding affinity (-10.95 kcal/mol) than penicillin (-10.89 kcal/mol) while compounds 3 and 4 had binding affinities (-10.07 and -10.62kcal/mol) comparable to ketoconazole (-10.85 kcal/mol).

Conclusion and implication:

All the synthesized compounds exhibited significant antibacterial and antifungal activities and were confirmed to be potential antimicrobial agents.

Evaluation of a new series of pyrazole derivatives as a potent epidermal growth factor receptor inhibitory activity: QSAR modeling using quantum-chemical descriptors

Pyrazole derivatives correspond to a family of heterocycle molecules with important pharmacological and physiological applications. At present, we perform a density functional theory (DFT) calculations and a quantitative structure-activity relationship (QSAR) evaluation on a series of 1-(4,5-dihydro-1H-pyrazol-1-yl) ethan-1-one and 4,5-dihydro-1H-pyrazole-1-carbothioamide derivatives as an epidermal growth factor receptor (EGFR) inhibitory activity. We thus propose a virtual screening protocol based on a machine-learning study. This theoretical model relates the studied compounds' biological activity to their calculated physicochemical descriptors. Moreover, the linear regression function is used to validate the model via the evaluation of Q² _ext and Q² _cv parameters for external and internal validations, respectively. Our QSAR model shows a good correlation between observed activities IC₅₀ and predicted ones. Our model allows us to mitigate time-consuming problems and waste chemical and biological products in the preclinical phases.

Formal Fluorinative Ring Opening of 2-Benzoylpyrrolidines Utilizing [1,2]-Phospha-Brook Rearrangement for Synthesis of 2-Aryl-3-fluoropiperidines

A ring expansion of 2-benzoylpyrrolidines, which involves the formal fluorinative ring opening utilizing the [1,2]-phospha-Brook rearrangement under Brønsted base catalysis and a subsequent intramolecular reductive amination, was developed. The operationally simple three-step protocol provides an efficient access to 2-aryl-3-fluoropiperidines. The methodology was further applied to the syntheses of azepanes and tetrahydroquinolines.

Diphenyl pyrimidine exhibits protective effect on Staphylococcus aureus pneumonia in rat model by targeting NLRP3 expression

Pneumonia is one of the most frequent disorder induced by S. aureus infection and accounts for 13.3% of the all the infections caused by staphylococcus. In the present study effect of diphenyl pyrimidine was investigated against Staphylococcus aureus (S. aureus) induced pneumonia in the rat model. The results demonstrated that diphenyl pyrimidine treatment of the rats effectively prevented S. aureus induced increase in mortality in dose-dependent manner. Diphenyl pyrimidine treatment inhibited histopathological changes in S. aureus infected rat lungs. Treatment of the rats with 1.25, 2.5, 5 and 10 mg/kg doses of diphenyl pyrimidine significantly (P < 0.05) reversed S. aureus infection induced increase in interleukin (IL)-1β, IL-18 and tumor necrosis factor (TNF)-α levels. Treatment with 1.25, 2.5, 5 and 10 mg/kg doses of diphenyl pyrimidine significantly (P < 0.05) reversed S. aureus infection induced increase nucleotide-binding domain and leucine-rich repeat containing (NLR) protein (NLRP3), apoptosis-associated speck-like protein containing a C-terminal caspase recruitment domain (ASC) and caspase-1 protein expression in rat lungs in dose-dependent manner. The NLRP3, ASC and caspase-1 mRNA level in S. aureus infected rat pulmonary tissues was significantly (P < 0.05) reduced by diphenyl pyrimidine treatment in dose-dependent manner. Thus, diphenyl pyrimidine protects S. aureus-induced pneumonia through suppression of NLRP3 and inflammatory cytokine expression. Therefore, diphenyl pyrimidine can be of therapeutic importance for the treatment of S. aureus induced pneumonia.

Azetidines of pharmacological interest

Azetidines are almost unexplored among nitrogen-containing saturated heterocycles due to difficulties associated with their synthesis. However, over the past few years, attempts have been made by scientists to advance their synthetic feasibility. Compounds with the azetidine moiety display an important and diverse range of pharmacological activities, such as anticancer, antibacterial, antimicrobial, antischizophrenic, antimalarial, antiobesity, anti-inflammatory, antidiabetic, antiviral, antioxidant, analgesic, and dopamine antagonist activities, and are also useful for the treatment of central nervous system disorders and so forth. Owing to its satisfactory stability, molecular rigidity, and chemical and biological properties, azetidine has emerged as a valuable scaffold and it has drawn the attention of medicinal researchers. The present review sheds light on the traditional method of synthesis of azetidine and advancements in synthetic methodology over the past few years, along with its application with various examples, and its biological significance.

Applications of aryl-sulfinamides in the synthesis of N-heterocycles

Enantiopure aryl-sulfinamides are important chiral auxiliaries in the asymmetric synthesis of amines and their derivatives. Here, we provide an overview of arylsulfinamide mediated asymmetric methods towards N-heterocycle synthesis. This methodology through sulfinylimines offers general access to structurally diverse piperidines, pyrrolidines, aziridines and their derivatives which represent the structural motif of many natural products and therapeutically important compounds. The review covers articles from 2006–2020 and we have categorized the review based on the ring size as 3-, 5-, and 6- membered heterocycles and their derivatives.

The review comprehends the usage of arylsulfinamides for the construction of diverse N-heterocycles like piperidines, pyrrolidines, aziridines, and their fused derivatives.

Recent Advancement of Pyrazole Scaffold Based Neuroprotective Agents: A Review

As a source of therapeutic agents, heterocyclic nitrogen-containing compounds and their derivatives are still interesting and essential. Pyrazole, a five-member heteroaromatic ring with two nitrogen atoms, has a major impact on chemical industries as well as pharmaceutical industries. Due to its wide range of biological activities against various diseases, it has been identified as a biologically important heterocyclic scaffold. The treatment of neurological disorders has always been a difficult task. Therefore, identifying therapeutically effective molecules for neurological conditions remains an open challenge in biomedical research and development. For developing novel entities as neuroprotective agents, recently, pyrazole scaffold has attracted medicinal chemists worldwide. The major focus of research in this area is to discover novel molecules as neuroprotective agents with minimal adverse effects and better effectiveness in improving the neurological condition. This review mainly covers recent developments in the neuropharmacological role of pyrazole incorporated compounds, including their structural-activity relationship (SAR), which also further includes IC50 values (in mM as well as in μM), recent patents, and a brief history as neuroprotective agents.

Recent advances on heterocyclic compounds with antiviral properties

In recent years several important viral infections have emerged and antiviral chemotherapeutic agents are not sufficiently effective in clinic, leading to serious human diseases and mortality. Therefore, novel antiviral candidates are urgently desirable, which undoubtedly is essential for the therapy of various fatal and debilitating viral infections. Heterocyclic compounds are obtaining importance in the field of medicinal chemistry because of the broad spectrum of their physiological activities. Among N- and S-containing heterocycles, indole, imidazole, thiazole, pyridine, and quinaxoline derivatives are especially attractive. The present review highlights antiviral behavior of these heterocyclic compounds.

Research developments in the syntheses, anti-inflammatory activities and structure-activity relationships of pyrimidines

Pyrimidines are aromatic heterocyclic compounds that contain two nitrogen atoms at positions 1 and 3 of the six-membered ring. Numerous natural and synthetic pyrimidines are known to exist. They display a range of pharmacological effects including antioxidants, antibacterial, antiviral, antifungal, antituberculosis, and anti-inflammatory. This review sums up recent developments in the synthesis, anti-inflammatory effects, and structure-activity relationships (SARs) of pyrimidine derivatives. Numerous methods for the synthesis of pyrimidines are described. Anti-inflammatory effects of pyrimidines are attributed to their inhibitory response versus the expression and activities of certain vital inflammatory mediators namely prostaglandin E2, inducible nitric oxide synthase, tumor necrosis factor-α, nuclear factor κB, leukotrienes, and some interleukins. Literature studies reveal that a large number of pyrimidines exhibit potent anti-inflammatory effects. SARs of numerous pyrimidines have been discussed in detail. Several possible research guidelines and suggestions for the development of new pyrimidines as anti-inflammatory agents are also given. Detailed SAR analysis and prospects together provide clues for the synthesis of novel pyrimidine analogs possessing enhanced anti-inflammatory activities with minimum toxicity.

Recent investigations into synthesis and pharmacological activities of phenoxy acetamide and its derivatives (chalcone, indole and quinoline) as possible therapeutic candidates

Medicinal chemistry can rightfully be regarded as a cornerstone in the public health of our modern society that combines chemistry and pharmacology with the aim of designing and developing new pharmaceutical compounds. For this purpose, many chemical techniques as well as new computational chemistry applications are used to study the utilization of drugs and their biological effects. In the biological interface, medicinal chemistry constitutes a group of interdisciplinary sciences, as well as controlling its organic, physical and computational pillars. Therefore, medicinal chemists working to design an integrated and developing system that portends an era of novel and safe tailored drugs either by synthesizing new pharmaceuticals or to improving the processes by which existing pharmaceuticals are made. It includes researching the effects of synthetic, semi-synthetic and natural biologically active substances based on molecular interactions in terms of molecular structure with triggered functional groups or the specific physicochemical properties. The present work focuses on the literature survey of chemical diversity of phenoxy acetamide and its derivatives (Chalcone, Indole and Quinoline) in the molecular framework in order to get complete information regarding pharmacologically interesting compounds of widely different composition. From a biological and industrial point of view, this literature review may provide an opportunity for the chemists to design new derivatives of phenoxy acetamide and its derivatives that proved to be the successful agent in view of safety and efficacy to enhance life quality.

Applications of tert-butanesulfinamide in the synthesis of N-heterocycles via sulfinimines

Chiral sulfinamides are among the best known chiral auxiliaries in the stereoselective synthesis of amines and their derivatives. The most extensively used enantiopure tert-butanesulfinamide emerged as the gold standard among many others over the last two decades. The present review attempts to provide an overview of tert-butanesulfinamide mediated asymmetric N-heterocycle synthesis via sulfinimines and covers literature from 2010-2020. This methodology offers general access to structurally diverse piperidines, pyrrolidines, azetidines, and their fused derivatives that represent the structural motif of many natural products and therapeutically applicable compounds.