Sustainable alternative protocols for the multicomponent synthesis of spiro-4H-pyrans catalyzed by 4-dimethylaminopyridine

A new DES-mediated synthesis of Henna-based benzopyranophenazines and benzoxanthenetriones

MTPPBr/THFTCA-DES was prepared as a new deep eutectic solvent (DES) from a mixture (molar ratio 7:3) of methyltriphenyl-phosphonium bromide (MTPPBr) and tetrahydrofuran-2,3,4,5-tetra-carboxylic acid (THFTCA), and characterized with various spectroscopic techniques, densitometer, and eutectic point. Then, it was used as a new and powerful catalyst for the synthesis of two sets of biologically important compounds, namely the Henna-based benzopyranophenazines and benzoxan-thenetriones. Solvent-free conditions, short reaction time, high efficiency, and easy recycling and separation of the DES catalyst are among the most important features of the presented method. Also, there is a nice consistency between the proposed structure of the DES compound, the integration values of the 1H NMR peaks, and the ratio of MTPPBr to THFTCA obtained from the eutectic point phase diagram. In addition, the reduction of peak splitting patterns in DES compared to the two primary materials can be good evidence of the formation of hydrogen bonds between the two components.

Recent developments on microwave-assisted organic synthesis of nitrogen- and oxygen-containing preferred heterocyclic scaffolds

In recent decades, the utilization of microwave energy has experienced an extraordinary surge, leading to the introduction of innovative and revolutionary applications across various fields of chemistry such as medicinal chemistry, materials science, organic synthesis and heterocyclic chemistry. Herein, we provide a comprehensive literature review on the microwave-assisted organic synthesis of selected heterocycles. We highlight the use of microwave irradiation as an effective method for constructing a diverse range of molecules with high yield and selectivity. We also emphasize the impact of microwave irradiation on the efficient synthesis of N- and O-containing heterocycles that possess bioactive properties, such as anti-cancer, anti-proliferative, and anti-tumor activities. Specific attention is given to the efficient synthesis of pyrazolopyrimidines-, coumarin-, quinoline-, and isatin-based scaffolds, which have been extensively studied for their potential in drug discovery. The article provides valuable insights into the recent synthetic protocols and trends for the development of new drugs using heterocyclic molecules.

Organocatalyzed Heterocyclic Transformations In Green Media: A Review

Background:

Since the discovery of metal-free catalysts or organocatalysts about twenty years ago, a number of small molecules with different structures have been used to accelerate organic transformations. With the development of environmental awareness, to obtain highly efficient scaffolds, scientists have directed their studies towards synthetic methodologies that minimize or preferably eliminate the formation of waste, avoid toxic solvents and reagents and use renewable starting materials as far as possible.

Methods:

In this connection, the organocatalytic reactions providing efficiency and selectivity for most of the transformations have become an endless topic in organic chemistry since several advantages from both practical and environmental standpoints. Organocatalysts contributing to the transformation of reactants into products with the least possible waste production, have been serving the concept of green chemistry.

Results and Conclusion:

Organocatalysts have been classified based on their binding capacity to the substrate with covalent or noncovalent interactions involving hydrogen bonding and electrostatic interaction. Diverse types of small organic compounds including proline and its derivatives, phase-transfer catalysts, (thio)urease, phosphoric acids, sulfones, N-oxides, guanidines, cinchona derivatives, aminoindanol, and amino acids have been utilized as hydrogen bonding organocatalysts in different chemical transformations.

New Approaches for the Synthesis of Heterocyclic Compounds Corporating Benzo[d]imidazole as Anticancer Agents, Tyrosine, Pim-1 Kinases Inhibitions and their PAINS Evaluations

BACKGROUND

Benzo[d]imidazoles are highly biologically active, in addition, they are considered as a class of heterocyclic compounds with many pharmaceutical applications.

OBJECTIVE

We are aiming in this work to synthesize target molecules that possess not only anti-tumor activities but also kinase inhibitors. The target molecules were obtained starting from the benzo[d]imidazole derivatives followed by their heterocyclization reactions to produce anticancer target molecules.

METHODS

The 1-(1H-benzo[d]imidazol-2-yl)propan-2-one (3) and the ethyl 2-(1H-benzo[d]imidazol-2- yl)acetate (16) were used as the key starting material which reacted with salicylaldehyde to give the corresponding benzo[4,5]imidazo[1,2-a]quinoline derivatives. On the other hand, both of them were reacted with different reagents to give thiophene, pyran and benzo[4,5]imidazo[1,2-c]pyrimidine derivatives. The synthesized compounds were evaluated against the six cancer cell lines A549, HT-29, MKN-45, U87MG, SMMC-7721, and H460 together with inhibitions toward tyrosine kinases, c-Met kinase and prostate cancer cell line PC-3 using the standard MTT assay in vitro, with foretinib as the positive control.

RESULTS

Most of the synthesized compounds exhibited high inhibitions toward the tested cancer cell lines. In addition, tyrosine and Pim-1 kinases inhibitions were performed for the most active compounds where the variation of substituent through the aryl ring and heterocyclic ring afforded compounds with high activities. Our analysis showed that there is a strong correlation between the structure of the compound and the substituents of target molecules.

CONCLUSION

Our present research proved that the synthesized heterocyclic compounds with varieties of substituents have a strong impact on the activity of compounds. The evaluations through different cell lines and tyrosine kinases indicated that the compounds were the excellent candidates as anticancer agents. This could encourage doing further research within this field for the building of compounds with high inhibitions.

Synthesis and evaluation of antimicrobial activity, cytotoxic and pro-apoptotic effects of novel spiro-4H-pyran derivatives

A new library of spiropyrans were synthesized via a one-pot four component reaction of cyanoacetohydrazide, ninhydrin, malononitrile and various cyclic CH-acids in EtOH at reflux conditions. The products were isolated and tested in vitro for antibacterial effects on Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). Furthermore cytotoxic activity of the spiropyrans on non-small-cell lung cancer cells (A549 cells), a breast epithelial cancer cell line (MCF-7), human malignant melanoma cells (A375), prostate cancer cells (PC3 cells, LNCaP cells) and normal cells HDF (human dermal fibroblast) was investigated. Interestingly, it was found that compounds 5a, 5b, 5f, 5g and 5i have the best MIC against S. auerus and compound 5a displayed the most potent activity against A549, A375, and LNCaP tumor cells. Moreover, DAPI staining of the A549 cancer cell lines that were treated with 5a were associated with the death of A549 cells. By using RT-PCR method, it was finally confirmed that apoptosis occurs in A549 cells by up-regulated Bax expression and down-regulated Bcl-2 expression from the mitochondrial pathway of apoptosis.

The molecular diversity scope of 4-hydroxycoumarin in the synthesis of heterocyclic compounds via multicomponent reactions

4-Hydroxycoumarins are some of the most versatile heterocyclic scaffolds and are frequently applied in the synthesis of various organic compounds. 4-Hydroxycoumarin-based compounds are important among heterocyclic structures due to their biological and pharmaceutical activities. In this study, we provide an overview on the recent applications of 4-hydroxycoumarin in multicomponent reactions for the synthesis of various heterocyclic compounds during the time period of 2015-2018.

Synthesis of Novel Thiophene, Thiazole and Coumarin Derivatives Based on Benzimidazole Nucleus and Their Cytotoxicity and Toxicity Evaluations

The reactivity of compounds 2-(1-(2-chloroacetyl)-1H-benzo[d]imidazol-2-yl)acetonitrile 2 and 3-(1-(2-chloroacetyl)-1H-benzo[d]imidazol-2-yl)-2H-chromen-2-one 8 towards different chemical reagents were studied and a series of novel benzimidazole derivatives were obtained (2-6a-d and 8-12a-d). Moreover, in vitro growth inhibitory effect of the newly synthesized compounds were evaluated in term of [IC₅₀ µM] against the six cancer cell lines, human lung carcinoma (A549), lung cancer (H460), human colorectal (HT29), gasteric cancer cell (MKN-45), glioma cell line (U87MG) and cellosaurus cell line (SMMC-7721) where foretinib was used as standard reference. The results showed that compounds 2 (only for A549 cell line), 3a, 4, 6c, 6d, 8, 9a, 9e and 9f were the most active compounds towards the six cancer cell lines. On the other hand, the toxicity of these most potent compounds against shrimp larvae indicated that compounds 3a, 4, 6d, 9e and 9f were non toxic while compounds 6c and 8 were very toxic and compounds 2 and 9a were harmful against the tested organisms.

Uses of Cyclohexan-1,4-dione for the Synthesis of 2-Amino-4,5-dihydrobenzo[b]thiophen-6(7H)-one Derivatives with Anti-proliferative and Pim-1 Kinase Activities

The reaction of cyclohexan-1,4-dione with elemental sulfur and any of the 2-cyano-N-arylacetamide derivatives 2a-c gave the 2-amino-4,5-dihydrobenzo[b]thiophen-6(7H)-one derivatives 3a-c to be used in some heterocyclization reactions. The multicomponent reactions of any of compounds 3a-c with aromatic aldehydes 6a-c and either of malononitrile or ethylcyanoacetate gave the 5,9-dihydro-4H-thieno[2,3-f]chromene derivatives 9a-r, respectively. The anti-proliferative evaluation of the newly synthesized compounds against the six cancer cell lines A549, HT-29, MKN-45, U87MG, SMMC-7721 and H460 showed that the nine compounds 3c, 5c, 9e, 9h, 9i, 9j, 9l, 9q, 11e and 13e with highest cytotoxcity. Toxicity of these compounds against shrimp larvae revealed that compounds 3c, 9j, 9q, and 13e showed no toxicity against the tested organisms. The c-Met kinase inhibition of the most potent compounds showed that compounds 9j, 9q, 10e, 12e and 13e have the highest activities. Compounds 9j, 9l, 9q and 11e showed high activity towards tyrosine kinases. Moreover, compounds 9j, 9q and 13e showed the highest inhibitor activity towards Pim-1 kinase.

An efficient, room temperature, oxygen radical anion (O2•−) mediated, one-pot, and multicomponent synthesis of spirooxindoles

The present report highlights an efficient use of oxygen radical anion to promote a room temperature multi-component synthesis of spirooxindoles (4a–4l) under mild reaction conditions. The potassium superoxide (KO2) and tetraethylammonium bromide (TEAB) combination generate the oxygen radical anion in situ to promote this transformation. This method offers a sustainable and direct access to the biologically important spirooxindole derivatives in good to excellent yields.

Synthesis of Novel Heterocyclic Compounds Incorporate 4,5,6,7-Tetrahydrobenzo[b]thiophene Together with Their Cytotoxic Evaluations

The 2-amino-3-cyano-4,5,6,7-tetrahydrobenzo[b]thiophene was the key starting compound used to synthesize new thiazole, pyrimidine, pyran, pyridine and thiazine derivatives. The cytotoxicity of the synthesized compounds was studied towards the three cancer cell lines namely MCF-7 (breast adenocarcinoma), NCI-H460 (non-small cell lung cancer) and SF-268 (central nervous system (CNS) cancer) in addition to the normal cell line (WI-38) using doxorubicin as the reference drug. The study showed that compounds 5, 9a, 15b, 17c, 18 and 21b were the most potent compounds.

Synthesis of spiropyran derivatives over 1-(carboxymethyl) pyridinium iodide as nanostructured pyridinium salt under aqueous media

In this work, acetic acid functionalized pyridinium salt, namely 1-(carboxymethyl)pyridinium iodide {[cmpy]I}, has been applied as reusable nanostructured catalyst for green, simple and efficient preparation of spiropyrans by the one-pot domino Knoevenagel–Michael–cyclization reaction of isatin derivatives or acenaphthenquinone, with malononitrile, and 1,3-dicarbonyl compounds under aqueous media. Moreover, 1H and 13C NMR, mass, CHN analysis, Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), thermal gravimetric analysis (TGA), differential thermal gravimetric (DTG), X-ray diffraction analysis (XRD), and calculation of crystallite size and interplaner distance of the catalyst have been studied.