Regioselective synthesis of pyrimidine-fused tetrahydropyridines and pyridines by microwave-assisted one-pot reaction

Developments of pyridodipyrimidine heterocycles and their biological activities

The entitled review aimed to assemble and highlight the synthetic approaches and biological aspects of heterocycles with pyridodipyrimidine motifs. The recent synthetic approaches were categorized according to the accomplishments of the approaches under catalyst or catalyst-free conditions. The topic involved the synthesis of substituted tricyclic systems and spirocyclic systems. The present study offered an overview of the recent literature in addition to a scope of the preceding literature. The proposed mechanisms of the varied target products were discussed. Pyridodipyrimidine displayed potential and privileged cytotoxic, antioxidant, and antimicrobial performances. The competitions, challenges, and prospects are also deliberated.

One-pot multicomponent synthesis of benzophenazine tethered tetrahydropyridopyrimidine derivatives

A simple, facile, and efficient green methodology has been developed for the synthesis of benzophenazine tethered tetrahydropyridopyrimidine derivatives by the one-pot four-component reaction of cinnamaldehyde/crotonaldehyde, 2-hydroxy-1,4-naphthoquinone, 1,3-dimethyl-6-amino uracil, and o-phenylenediamine in ethanol medium under reflux conditions using p-TSA as a catalyst. In this environmentally benign methodology, three C-N and two C-C bonds are formed in one pot. The hybrid products have three bioactive moieties such as benzophenazine, tetrahydropyridine, and pyrimidine. Operational simplicity, metal-free conditions, wide substrate scope, readily available starting materials, moderate to good yields of the desired products, presence of pharmaceutically active moieties, and easy purification process are the notable features of this methodology.

Antibacterial and antioxidant assay of novel heteroaryl-substituted methane derivatives synthesized via ceric ammonium nitrate (CAN) catalyzed one-pot green approach

Individually, hydroxycoumarin and amino pyrimidine derivatives are of significant biological interest owing to their importance in drugs and pharmaceuticals. To access their combined biological impact into one molecule, we designed a novel, one-pot green approach for synthesizing trisubstituted methanes. A series of new heteroaryl-substituted methanes have been synthesized and subjected to in vitro antibacterial and antioxidant evaluation. Tests against clinical isolates of Escherichia coli (gram-negative) and Staphylococcus aureus showed potent activity of the derivatives 4a, 4b, 4d, 4e, 4f, 4l, and 5 against the former, and 4a, 4e, 4j, and 4l against the later one. Further, antioxidant assay for these TRSMs was also studied where 4a, 4b, 4f, 4j, and 4l exhibited the most promising results. These preliminary bioassay evaluations strongly suggest the promise and scope of these molecules in medical science. A one pot methodology for the synthesis of coumarin and uracil tethered trisubstituted methanes has been reported. The synthesized derivatives were further analyzed for their antibacterial and antioxidant properties to explore their medicinal applications. The salient features of this methodology are operational simplicity, short reaction time, good to moderate yields of the products, easy purification method. Biochemical assay of the synthesized TRSMs a reveals their utility in medicinal & pharma industry.

Evaluation of xanthene-appended quinoline hybrids as potential leads against antimalarial drug targets

A series of fused heterocycle xanthene-appended quinoline 6a-n was successfully synthesized with regioselectivity and characterized using IR, ¹H NMR, ¹³C NMR, and mass spectral data. Molecular docking was performed to find the binding efficacy of all these newly synthesized compounds towards thirteen antimalarial drug targets. Molecular dynamics simulation was carried out to predict the stability of the ligand-bound complex in a solvent medium. Blind and site-directed docking with compounds 6a-n against 13 drug targets revealed most of the ligands to have a good binding affinity with the targets. Analysis on the basis of binding energy, binding modalities of the ligands, intermolecular interactions, and pharmacophore, we identified only one of the ligand-receptor complexes to provide better results. Molecular dynamic simulation of the selected receptor-ligand complex revealed that the synthesized compound had a better binding affinity with the receptor than the native ligand complex. Further analysis of the synthesized ligand in the laboratory may prove promising results in the search for potential antimalarial drugs.

Recent Progress in the Synthesis of Heterocycles Based on 1,3-Diketones

N,O-heterocycles containing the dicarbonyl ring play a significant role in heterocyclic and therapeutic chemistry. Since the discovery of 1,3-diketones, numerous research works have been achieved regarding the synthesis and its chemical reactivity. In this review, we have described the most relevant publications involving β-diketone compounds published during the period between 2018 to date. In addition, we include the 1,3-diketones-based heterocyclic compounds prepared by various synthetic methodologies.

Synthesis of styryl-linked fused dihydropyridines by catalyst-free multicomponent reactions

Herein, we report a rapid catalyst-free three-component reaction of 2-hydroxy-1,4-naphthoquinone, cinnamaldehydes and 3-aminopyrazoles in ethanol medium under reflux conditions for the easy access of styryl-linked dihydropyridines fused with naphthoquinone and pyrazole moiety. A wide variety of cinnamaldehyde derivatives and 3-aminopyrazoles were found suitable for this three-component reaction. All the products were fully characterized by spectroscopic tools and by recording single crystal XRD of one of the product. Catalyst-free reaction conditions, short reaction time, good yields of the products, easy purification process, formation of three new bonds (Two C-C and one C-N) in one-pot and products having four different bioactive moieties are the notable features of this methodology.

The microwave-assisted syntheses and applications of non-fused single-nitrogen-containing heterocycles

Microwave technology has emerged as a great tool for the efficient synthesis of organic compounds and it provides opportunities for chemists to achieve chemical transformations that tend to be challenging using classical approaches. Additionally, N-heterocycles are well-known for their medicinal/biological significance, along with their applications as excellent building blocks in chemical synthesis. The dominance of N-heterocycles in drug molecules and other pharmacological agents makes them attractive scaffolds, which encourages chemists to develop a wide range of strategies towards the greener synthesis and functionalization of these heterocycles. In this regard, we have collated and discussed literature relating to the microwave-assisted synthesis and the modification of non-(benzo)fused single-nitrogen-containing N-heterocycles from the past decade. The role of the microwave technique and its benefits over the conventional approach have also been emphasized in terms of overall reaction efficiency, reaction time, yield, reduced side-product generation, neat and clean reactions, chemo-/regio-/enantio-selectivity, and the use of mild reagents/reaction conditions to achieve the objectives of green and sustainable chemistry.