Synthesis and antitumor activity of some indeno[1,2-b]quinoline-based bis carboxamides

Efficient synthesis of benzoacridines and indenoquinolines catalyzed by acidic magnetic dendrimer

A novel solid acid catalyst with recoverability, named as Fe3O4@SiO2@TAD-G2-SO3H, was successfully synthesized by immobilizing sulfonic acid groups on triazine dendrimer-modified magnetic nanoparticles. This nanomaterial structure and composition were thoroughly characterized using various analytical techniques, including thermogravimetric analysis (TGA), elemental analysis, Fourier transform infrared spectroscopy (FT-IR), energy-dispersive X-ray spectroscopy (EDX), elemental mapping, acid-base titration, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and vibrating sample magnetometry (VSM). The acid-decorated magnetic dendrimer was served as a highly effective catalyst for the synthesis of tetrahydrobenzo[c]acridin-8(9H)-one and benzo[h]indeno[1,2-b]quinoline-8-one derivatives. The reaction proceeded smoothly under mild conditions through the one-pot condensation of aromatic aldehydes, 1-naphthylamine, and either dimedone or 1,3-indanedione, affording the desired products in high yields ranging from 90 to 96%. The catalyst was easily separated from the reaction mixture by employing a magnetic field, allowing for its recycling up to five times with slight loss in its activity (only 10%). Nearly, quantitative recovery of catalyst (up to 95%) could be obtained from each run. So, this catalyst facilitates the reaction progress and simplifies the purification process. Other remarkable features of this method are operational simplicity, excellent yields, mild condition, and a wide range of substrate applicability.

Indole-fused spirochromenes as potential anti-tubercular agents: design, synthesis and in vitro evaluation

As part of an ongoing effort to develop new anti-tubercular agents, a series of novel indole-fused spirochromene hybrids (7a-l) were efficiently synthesized in excellent yields by the popular 'Fisher-Indole synthesis' approach. The structure elucidation of the target compounds was carried out by different spectral techniques including 1H-NMR, 13C-NMR, ESI Mass, and FTIR analysis. Additionally, the proposed structure of 7i was proved by single-crystal X-ray analysis. These compounds (7a-l) were screened for in vitro anti-tubercular activity against Mycobacterium tuberculosis H37Rv (ATCC 27294) strain. The results showed that most of the targets exhibited promising antimycobacterial activity with MICs of 1.56-6.25 μg/mL and weak cytotoxicity (19.93-32.16% at 50 μg/mL). Among them, compound 7l was found to be the most active compound (MIC of 1.56 μg/mL) with a good safety profile (32.16% at 50 μg/mL).

Dimeric Drugs

This review intends to summarize the structures of an extensive number of symmetrical-dimeric drugs, having two monomers linked via a bridging entity while emphasizing the large versatility of biologically active substances reported to possess dimeric structures. The largest number of classes of these compounds consist of anticancer agents, antibiotics/antimicrobials, and anti-AIDS drugs. Other symmetrical-dimeric drugs include antidiabetics, antidepressants, analgesics, anti-inflammatories, drugs for the treatment of Alzheimer's disease, anticholesterolemics, estrogenics, antioxidants, enzyme inhibitors, anti-Parkisonians, laxatives, antiallergy compounds, cannabinoids, etc. Most of the articles reviewed do not compare the activity/potency of the dimers to that of their corresponding monomers. Only in limited cases, various suggestions have been made to justify unexpected higher activity of the dimers vs. the corresponding monomers. These suggestions include statistical effects, the presence of dimeric receptors, binding of a dimer to two receptors simultaneously, and others. It is virtually impossible to predict which dimers will be preferable to their respective monomers, or which linking bridges will lead to the most active compounds. It is expected that the extensive number of articles summarized, and the large variety of substances mentioned, which display various biological activities, should be of interest to many academic and industrial medicinal chemists.

Fe3O4@urea/HITh-SO3H as an efficient and reusable catalyst for the solvent-free synthesis of 7-aryl-8H-benzo[h]indeno[1,2-b]quinoline-8-one and indeno[2′,1′:5,6]pyrido[2,3-d]pyrimidine derivatives

In this study, Fe3O4@urea/HITh-SO3H MNPs as a new, efficient, and recyclable solid acid magnetic nanocatalyst was synthesized and characterized using various methods including Fourier transform infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy, transmission electron microscopy, vibrating sample magnetometry, energy-dispersive X-ray spectroscopy, and X-ray powder diffraction. After the characterization of this new magnetic nanocatalyst, it was efficiently utilized for the promotion of the one-pot synthesis of 7-aryl-8H-benzo[h]indeno[1,2-b]quinoline-8-one and indeno[2′,1′:5,6]pyrido[2,3-d]pyrimidine derivatives via three-component reaction of the 1,3-indanedione, aldehyde, and 1-naphthylamine/1,3-dimethyl-6-aminouracil under solvent-free conditions at 80°C. The procedure gave the desired heterocyclic structures in high-to-excellent yields and short reaction times. Also because of the magnetic nature of the nanocatalyst, it can be separated with an external magnetic field and reused at least six runs without any considerable decrease in the catalytic behavior.

Recent applications of ninhydrin in multicomponent reactions

Ninhydrin (1,2,3-indanetrione hydrate) has a remarkable breadth in different fields, including organic chemistry, biochemistry, analytical chemistry and the forensic sciences. For the past several years, it has been considered an important building block in organic synthesis. Therefore, there is increasing interest in ninhydrin-based multicomponent reactions to rapidly build versatile scaffolds. Most of the works described here are simple reactions with readily available starting materials that result in complex molecular architectures. Some of the synthesized compounds exhibit interesting biological activities and constitute a new hope for anticancer agents. The present review aims to highlight the multicomponent reactions of ninhydrin towards diverse organic molecules during the period from 2014 to 2019.

This article aims to review recent multicomponent reactions of ninhydrin towards diverse organic scaffolds, such as indeno-fused heterocycles, spiro-indeno heterocycles, quinoxalines, propellanes, cage-like compounds, and dispiro heterocycles.

Rhodium catalyzed cascade cyclization featuring B-H and C-H activation: one-step construction of carborane-fused N-polyheterocycles

A one-pot strategy for efficient and facile synthesis of C,B-substituted carborane-fused N-polyheterocycles is reported. A rhodium catalyzed cascade cyclization of carboranyl N-arylimines with vinyl ketones enables the effective construction of three new B-C and C-C bonds in one reaction. Both carboranyl B-H and aryl C-H bonds are sequentially activated, leading to a series of previously unavailable C,B-substituted carborane-fused cyclopenta[b]quinoline derivatives, for potential applications in pharmaceuticals and materials, in a step-economical manner. The successful isolation and structural identification of a key intermediate provide solid evidence for the reaction mechanism, involving a tandem sequence of regioselective B-H activation, alkene insertion, nucleophilic cyclization, C-H activation, nucleophilic cyclization, dehydration and oxidative aromatization.

Bis-spirochromanones as potent inhibitors of Mycobacterium tuberculosis: synthesis and biological evaluation

On the basis of reported antimycobacterial property of chroman-4-one pharmacophore, a series of chemically modified bis-spirochromanones were synthesized starting from 2-hydroxyacetophenone and 1,4-dioxaspiro[4.5] decan-8-one using a Kabbe condensation approach. The synthesized bis-spirochromanones were established based on their spectral data and X-ray crystal structure of 6e. All synthesized compounds were evaluated against Mycobacterium tuberculosis H37Rv (ATCC 27294) strain, finding that some products exhibited good antimycobacterial activity with minimum inhibitory concentration as low as [Formula: see text]. Docking studies were carried out to identify the binding interactions of compounds II, 6a and 6n with FtsZ. Compounds exhibiting good in vitro potency in the MTB MIC assay were further evaluated for toxicity using the HEK cell line.

Methyl 2-phenylquinoline-4-carboxylate

The asymmetric unit of the title compound, C17H13NO2, contains two independent molecules which differ primarily in the rotational orientation of the pendant phenyl group, being conrotatory, with respect to the plane of the quinoline moiety. In the crystal, the molecules form stacks parallel to the b axis through π–π stacking interactions of the heterocyclic rings [shortest inter-centroid distance = 3.5775 (8) Å].

A new chemical inhibitor of angiogenesis and tumorigenesis that targets the VEGF signaling pathway upstream of Ras

The efficacy of anti-angiogenic therapies on cancer patients is limited by the emergence of drug resistance, urging the search for second-generation drugs. In this study, we screened an academic chemical library (DCM, University of Grenoble-Alpes) and identified a leader molecule, COB223, that inhibits endothelial cell migration and proliferation. It inhibits also Lewis lung carcinoma (LLC/2) cell proliferation whereas it does not affect fibroblast proliferation. The anti-angiogenic activity of COB223 was confirmed using several in vitro and in vivo assays. In a mouse LLC/2 tumor model, ip administration of doses as low as 4 mg/kg COB223 efficiently reduced the tumor growth rate. We observed that COB223 inhibits endothelial cell ERK1/2 phosphorylation induced by VEGF, FGF-2 or serum and that it acts downstream of PKC and upstream of Ras. This molecule represents a novel anti-angiogenic and anti-tumorigenic agent with an original mechanism of action that deserves further development as an anti-cancer drug.

Metal free TBHP-promoted intramolecular carbonylation of arenes via radical cross-dehydrogenative coupling: synthesis of indenoquinolinones, 4-azafluorenones and fluorenones

Analogues of indenoquinolinones, 4-azafluorenones and fluorenones were accessed in good to excellent yields. One of the synthesized derivative is known for antibacterial activity.

Novel synthesis of a series of spiro 1,3-indanedione-fused dihydropyridines through the condensation of a tetrone with N-aryl/alkylenamines in presence of solid support silica sulfuric acid

A convenient protocol for the library synthesis of biologically important 1-aryl-2',6-spiro(1',3'-indanedione)-1H-indeno[1,2-b]quinoline-5,7-diones has been developed. In this one-pot reaction protocol a tetrone is condensed with various N-aryl/alkylenamines of 1,3-cyclohexadiones on the surface of a solid-supported acid catalyst silica sulfuric acid under solvent-free condition. The significant advantages of this methodology are the use of solvent-free reaction conditions, operational simplicity of the reaction, good yield of the products with high atom economy, and employment of a recyclable catalyst. All these favorable factors make the present method convenient, economic, and 'benign by design'.

O-Acetylation: Synthesis of Acetylated Phenols from Aryl-Methyl Ethers Over Boron Alkoxides

A new acetylation procedure has been applied to 13 aryl-methyl ethers using boron chemistry. In this procedure, demethylation of aryl-methyl ethers and acetylation of the resulting phenols were combined into one procedure in order to shorten the number of stages and to achieve easy purification. Eleven known with/without bromine and two new [bis(3,4-diacetoxyphenyl)methanone and 5,5'-methylenebis(1,2-diacetoxy-3,4-dibromobenzene) (a natural bromophenol's acetylated derivative)] acetylated arene compounds were synthesised from their methoxy derivatives by this method. The effectiveness of the method was illustrated by producing an acetylated natural bromophenol from its methyl ether. The phenol form was obtained by hydrolysing the acetylated natural bromophenol. Thus, the advantage of this method in the natural product chemistry of phenolic compounds was confirmed.

Ultrasound Promoted One-Pot Three-Component Synthesis of Novel 7-Aryl-8H-Benzo[h]Indeno[1,2-b]Quinolin-8-Ones Under Solvent-Free Conditions

A series of novel derivatives of 7-phenyl-8 H-benzo[h]indeno[1,2-b]quinolin-8-ones were synthesised directly by one-pot three-component reaction of indanedione, α-naphthylamine and various substituted arylaldehydes under solvent-free conditions using ultrasonic irradiation as a clean source of energy. This fast method provided the products in high yields (70–93%) and low reaction times (10–75 min).

Quinone methide generation via photoinduced electron transfer

Photochemical activation of water-soluble 1,8-naphthalimide derivatives (NIs) as alkylating agents has been achieved by irradiation at 310 and 355 nm in aqueous acetonitrile. Reactivity in aqueous and neat acetonitrile has been extensively investigated by laser flash photolysis (LFP) at 355 nm, as well as by steady-state preparative irradiation at 310 nm in the presence of water, amines, thiols, and ethyl vinyl ether. Product distribution analysis revealed fairly efficient benzylation of the amines, hydration reaction, and 2-ethoxychromane generation, in the presence of ethyl vinyl ether, resulting from a [4 + 2] cycloaddition onto a transient quinone methide. Remarkably, we found that the reactivity was dramatically suppressed under the presence of oxygen and radical scavengers, such as thiols, which was usually associated with side product formation. In order to unravel the mechanism responsible for the photoreactivity of these NI-based molecules, a detailed LFP study has been carried out with the aim to characterize the transient species involved. LFP data suggest a photoinduced electron transfer (PET) involving the NI triplet excited state (λ(max) 470 nm) of the NI core and the tethered quinone methide precursor (QMP) generating a radical ions pair NI(•-) (λ(max) 410 nm) and QMP(•+). The latter underwent fast deprotonation to generate a detectable phenoxyl radical (λ(max) 390 and 700 nm), which was efficiently reduced by the radical anion NI(•-), generating detectable QM. The mechanism proposed has been validated through a LFP investigation at 355 nm exploiting an intermolecular reaction between the photo-oxidant N-pentylnaphthalimide (NI-P) and a quaternary ammonium salt of a Mannich base as QMP (2a), in both neat and aqueous acetonitrile. Remarkably, these experiments revealed the generation of the model o-QM (λ(max) 400 nm) as a long living transient mediated by the same reactivity pathway. Negligible QM generation has been observed under the very same conditions by irradiation of the QMP in the absence of the NI. Owing to the NIs redox and recognition properties, these results represent the first step toward new molecular devices capable of both biological target recognition and photoreleasing of QMs as alkylating species, under physiological conditions.

Efficient and direct synthesis of poly-substituted indeno[1,2-b]quinolines assisted by p-toluene sulfonic acid using high-temperature water and microwave heating via one-pot, three-component reaction

Reactions of aldehydes, 1,3-indanedione and enaminones were successfully carried out using p-toluene sulfonic acid (p-TsOH) as a catalyst and high-temperature water as a solvent under microwave irradiation. This method provided several advantages such as rapid reaction times, high yields, and a simple workup procedure. In addition, a possible mechanism to account for the reaction was proposed.