Novel 1,4-dihydropyrano[2,3-c]pyrazole derivatives: Synthesis, characterization, biological evaluation and in silico study

A Comprehensive Examination of Heterocyclic Scaffold Chemistry for Antitubercular Activity

Tuberculosis is a communicable disease which affects humans particularly the lungs and is transmitted mainly through air. Despite two decades of intensive research aimed at understanding and combating tuberculosis, persistent biological uncertainties continue to hinder progress. Nowadays, heterocyclic compounds have proven themselves in effective treatment of tuberculosis because of their wide range of biological and pharmacological activities. Antituberculosis or antimycobacterial agents encompass a broad array of compounds utilized singly or in conjunction to combat Mycobacterium infections, spanning from tuberculosis to leprosy. Here, we summarize the synthesis of various heterocyclic compounds which includes the greener synthetic route as well as use of nano compounds as catalyst along with their anti TB activities.

Alamir H, Al-Shukarji AH, Ahmed BA, Qassem TA, Kamal M, Almeleebia TM, Alwaily ER, Hasan Kadhum E, Alawadi A, Alsalamy A. Choline chloride/urea as a green and efficient deep eutectic solvent in three-component and four-component synthesis of novel pyrazole and pyrano[2,3-c] pyrazole derivatives with antibacterial and antifungal activity

In this study, choline chloride/urea was used as a green deep eutectic solvent in the three-component reaction of hydrazine/phenylhydrazine, malononitrile, and aromatic aldehydes for synthesizing pyrazole derivatives, and in the four-component reaction of methyl/ethyl acetoacetate, hydrazine/phenylhydrazine, malononitrile, and aromatic aldehydes for synthesizing pyrano[2,3-c]pyrazole derivatives. Elemental analysis, 1H, and 13C NMR spectroscopy were used to confirm the structure of the synthesized pyrazole and pyrano[2,3-c] pyrazole derivatives. The antimicrobial effects of the synthesized pyrazole and pyrano[2,3-c] pyrazole derivatives were investigated. In antimicrobial tests, instructions from clinical and laboratory standards institutes were used. Antimicrobial study was done on pathogenic gram-positive and gram-negative species, and specialized aquatic strains and fungal species. Using choline chloride/urea, novel pyrazole derivatives and pyrano[2,3-c]pyrazole derivatives were synthesized, and other derivatives were synthesized with higher efficiency in less time than some previously reported methods. MIC (minimum inhibitory concentration) and MBC (minimum bactericidal concentration) obtained for derivatives were higher than some antibiotic drugs. Synthesis and reports of new derivatives of pyrazole and pyrano[2,3-c]pyrazole, and investigation and reports of their antimicrobial properties on gram-positive, gram-negative, and specialized aquatic and fungal species are among the novel and important findings of this study.

Green multicomponent synthesis of pyrano[2,3-c]pyrazole derivatives: current insights and future directions

The past decade has witnessed significant progress in synthesizing structurally diverse and biologically relevant pyrano[2,3-c]pyrazole derivatives through the integration of green methodologies. This review summarizes the recent advances in the green multicomponent synthesis of pyrano[2,3-c]pyrazole and spiro-pyrano[2,3-c]pyrazole derivatives. These include the application of energy-efficient techniques such as microwave and ultrasound-assisted synthesis, benign catalysts and biodegradable composites, solvent selection with a focus on water as a renewable and non-toxic medium, and solvent-free conditions. The review consolidates the current knowledge and future research directions, providing a valuable resource for researchers dedicated to advancing green chemistry practices.

Water-SDS-[BMIm]Br composite system for one-pot multicomponent synthesis of pyrano[2,3-c]pyrazole derivatives and their structural assessment by NMR, X-ray, and DFT studies

Here, we report a simple, efficient, and green protocol for the one-pot synthesis of pyrano[2,3-c]pyrazole derivatives via a sequential three-component strategy using aromatic aldehydes, malononitrile and pyrazolin-5-one in a water-SDS-ionic liquid system. This is a base and volatile organic solvent-free approach that could be applicable to a wide substrate scope. The key advantages of the method over other established protocols are very high yield, eco-friendly conditions, chromatography-free purification and recyclability of the reaction medium. Our study revealed that the N-substituent present in pyrazolinone controls the selectivity of the process. N-unsubstituted pyrazolinone favours the formation of 2,4-dihydro pyrano[2,3-c]pyrazoles whereas under identical conditions N-phenyl substituent pyrazolinone favours the formation 1,4-dihydro pyrano[2,3-c]pyrazoles. Structures of the synthesized products were established by NMR and X-ray diffraction techniques. Energy optimized structures and energy gaps between the HOMO-LUMO of some selected compounds were estimated using density functional theory to explain the extra stability of the 2,4-dihydro pyrano[2,3-c]pyrazoles over 1,4-dihydro pyrano[2,3-c]pyrazoles.

Identification of novel anti-tuberculosis agent: An in silico investigation

BACKGROUND

Multi-drug resistance tuberculosis is chronic and highly affected to mankind. Millions of people are affected by tuberculosis and lost their lives every year. Mycobacterium tuberculosis is resistant to the most commonly used anti-TB drugs, hence new drugs need to be developed in a short time. In this direction, many chemical compounds including benzimidazole derivatives have been identified as potent anti-tb agents.

METHOD

Various benzimidazole derivatives were subjected to in-silico computational screening to identify the potent anti-tubercular analogues. The ADME pharmacokinetics evaluation was performed to identify the drug-like molecules. Molecular docking investigation of selected compounds was performed against Mycobacterium Tuberculosis Enoyl Reductase (Inha) with PDB ID: 2B37, 1QG6, 4TZK, and 4TZK. The common pharmacophore hypothesis was generated using the molecular docking post-processing module.

RESULT

The result of ADME pharmacokinetics of some compounds is very close to the drug-like properties and can be developed as good inhibitors. Molecular docking study suggests that the proposed benzimidazole and 4H-pyran derivative have better binding affinity than standard and triclosan derivatives. Results from the pharmacophore hypothesis development study also support and suggest our prediction regarding the minimum pharmacophore features required in ligands to behave as a Mycobacterium Tuberculosis inhibitor.

CONCLUSION

Coumarin, phenylurea clubbed benzimidazole moiety and pyrano[2,3-c]pyrazole derivatives have shown greater selectivity and potency towards Mycobacterium Tuberculosis. By employing a combination of ADME, docking, and pharmacophore study calculations, novel potent hits to inhibit enoyl-acp reductase were identified with the points for consideration for designing of enoyl-acp reductase inhibitor.

A New Pathway for the Preparation of Pyrano[2,3-c]pyrazoles and molecular Docking as Inhibitors of p38 MAP Kinase

We report a new pathway to synthesize pyrano[2,3-c]pyrazoles and their binding mode to p38 MAP kinase. Pyrano[2,3-c]pyrazole derivatives have been prepared through a four-component reaction of benzyl alcohols, ethyl acetoacetate, phenylhydrazine, and malononitrile in the presence of sulfonated amorphous carbon and eosin Y as catalysts. All products were characterized by melting point, ¹H and ¹³C NMR, and HRMS (ESI). The products were screened in silico for their binding activities to both the ATP-binding pocket and the lipid-binding pocket of p38 MAP kinase, using a structure-based flexible docking provided by the engine ADFR. The results showed that eight synthesized compounds had a higher affinity to the lipid pocket than to the other target site, which implied potential applications as allosteric inhibitors. Finally, the most biologically active compound, 5, had a binding affinity comparable to those of other proven lipid pocket inhibitors, with affinity to the target pocket reaching -10.9932 kcal/mol, and also had the best binding affinity to the ATP-binding pockets in all of our products. Thus, our research provides a novel pathway for synthesizing pyrano[2,3-c]pyrazoles and bioinformatic evidence for their biological capability to block p38 MAP kinase pockets, which could be useful for developing cancer or immune drugs.

Palladium-catalysed diastereodivergent inverse-electron-demand oxa-Diels-Alder reactions of in situ formed cyclopentadienones via ligand-control

Here we report Pd(0)-catalysed asymmetric inverse-electron-demand oxa-Diels-Alder reactions between the carbonates of 4-hydroxy-2-cyclopentenones and α-cyano chalcones, by in situ generating η2-Pd(0)-cyclopentadienone complexes as HOMO-raised dienophiles, and diastereodivergent synthesis could be...

Synthesis, Anti-Bacterial and Anti-Oxidant Activity of Azo-Oxazolone and Their Ring Opening Azo-Benzamide Derivatives

This article describes the controlled synthesis and characterization of azo oxazolone scaffold compounds containing multifunctional groups such as carbonyl group, imine and carbon-carbon double bond. The reaction of the azo-oxazolone with aromatic amines led to the ring-opening of the azo-oxazolone into the corresponding azo-benzamide derivatives in a short time (average 10 min), resulting in high yield (>90%). All newly synthesized compounds were characterized by the common spectral analysis such as UV, IR, ¹H-NMR, ¹³CNMR, Elemental analysis and MS spectrometry.

OBJECTIVE

The aim of the study was to synthesize new bioactive azo-benzamides by using azo-oxazolone as a synthon utilizing its ring-opening function.

MATERIALS AND METHODS

Azo-benzamide derivatives were prepared in very good yield via ring-opening reaction of azo-oxazolone with aromatic amines in the presence of acetic acid under reflux for few minutes.

RESULTS AND DISCUSSION

Chemical structures of the newly synthesized compounds were characterized by UV, IR, ¹H-NMR, ¹³C-NMR, Elemental analysis and MS spectrometry.

CONCLUSION

The new azo-oxazolone 4 and azo-benzamide compounds 5a, 5c, 5f, 5h, 5j were screened against Escherichia coli as G(-ve) and Staphylococcus aureus as G(+ve) using ciprofloxacin as a standard. All compounds showed high inhibition potency against E-Coli but low inhibition for S-aureus. Compounds 4, 5c, and 5J showed more reactivity against E-coli. Others: Also, the compounds were tested for their anti-oxidant activity by both DPPH and FRAP methods. The results showed that some compounds possessed moderate anti-oxidant activity in comparison to ascorbic acid as control, typically the compounds bearing OCH₃ and OCH₂CH₃ groups.