Synthesis, antimicrobial and antioxidant evaluation of quinolines and bis(indolyl)methanes

FeCl3-Catalyzed Decyanative [4 + 2] Annulation of α-Aminonitriles with Alkynes: Access to 2,4-Diaryl Quinolines in Batch and Continuous-Flow Processes

FeCl₃-catalyzed decyanation of α-aminonitriles followed by a [4 + 2] annulation with terminal alkynes has been developed to synthesize 2,4-diaryl quinolines. A broad range of aniline, aldehyde, and arylacetylene derivatives were well tolerated to access 2,4-diaryl quinolines in moderate to good yields. The control experiment studies suggested that the reaction proceeds through a nonradical pathway involving Povarov-type [4 + 2] annulation from the in situ generated iminium species. The synthetic application of this strategy (i) includes gram-scale synthesis and (ii) a continuous-flow process for a few representative compounds in a shorter reaction time (22 min) and (iii) worked well with styrene as a proof of concept.

2-(4-Chlorophenyl)-4-(3,4-dimethoxy-phenyl)-6-methoxy-3-methylquinoline

A 2,4-diarylquinoline derivative, 2-(4-chlorophenyl)-4-(3,4-dimethoxyphenyl)-6-methoxy-3-methylquinoline, was synthesized in a conventional two-step procedure from p-anisidine, p-chlorobenzaldehyde and methyl isoeugenol as available starting reagents through a sequence of BF3·OEt2-catalyzed Povarov cycloaddition reaction/oxidative dehydrogenation aromatization processes under microwave irradiation conditions in the presence of a green oxidative I2-DMSO system. The structure of the compound was fully characterized by FT-IR, 1H and 13C-NMR, ESI-MS, and elemental analysis. Its physicochemical parameters (Lipinski’s descriptors) were also calculated using the Molinspiration Cheminformatics software. The diarylquinoline molecule obtained is an interesting model with increased lipophilicity and thus permeability, an important descriptor for quinoline-based drug design. Such types of derivatives are known for their anticancer, antitubercular, antifungal, and antiviral activities.

Synthesis and antifungal evaluation of phenol-derived bis(indolyl)methanes combined with FLC against Candida albicans

With the widespread use of azole antifungals in the clinic, the drug resistance has been emerging continuously. In this work, we focus on boron trifluoride etherate catalyzed condensation of indole and salicylaldehydes to form bis(indolyl)methanes (BIMs) in high yields, and in vitro antifungal activity against Candida albicans were evaluated. The results showed that most phenol-derived BIMs combined with fluconazole (FLC) exhibited good antifungal activity against sensitive and drug-resistant C. albicans. Further mechanism study demonstrated that BI-10 combined with FLC could inhibit hyphal growth, result in ROS accumulation, and decrease mitochondrial membrane potential (MMP) as well as altering membrane permeability.

Borane-Catalyzed Dehydrogenative C‒C Bond Formation of Indoles with N-Tosylhydrazones: An Experimental and Computational Study

A novel dehydrogenative C‒C bond formation of indoles and N-tosylhydrazones to di(indolyl)methanes (DIMs) has been demonstrated using tris(pentafluorophenyl)borane as catalyst. A wide range of functional groups can be tolerated under...

Recent Advancement in the One-Pot Synthesis of the Tri-Substituted Methanes (TRSMs) and Their Biological Applications

The history of tri-substituted methanes (TRSMs) in chemical industries is much older. Tri-substituted methanes were previously used as dyes in the chemical industries. Still, there is a significant surge in researchers' interest in them due to their wide range of bioactivities. Tri-substituted methane derivatives show a wide range of biological activities like anti-tumor, antimicrobial, antibiofilm, antioxidant, anti-inflammatory, anti-arthritic activities. Due to the wide range of medicinal applications shown by tri-substituted methanes, most of the methodologies reported in the literature for the synthesis of TRSMs are focused on the one-pot method. This review explored the recently reported one-pot processes for synthesizing tri-substituted methanes and their various medicinal applications. Based on the substitution attached to the -CH carbon, this review categorizes them into two major classes: (I) symmetrical and (II) unsymmetrical trisubstituted methanes. In addition, this review gives an insight into the growing opportunities for the construction of trisubstituted scaffolds via one-pot methodologies. To the best of our knowledge, no one has yet reported a review on the one-pot synthesis of TRSMs. Therefore, here we present a brief literature review of the synthesis of both symmetrical and unsymmetrical TRSMs covering various one-pot methodologies along with their medicinal applications.

Cycloisomerization of π-Coupled Heteroatom Nucleophiles by Gold Catalysis: En Route to Regiochemically Defined Heterocycles

Since the dawn of millennium, catalytic gold chemistry is at the forefront to set off diverse organic reactions via unique activation of π-bonded molecules. Within this purview, cycloisomerization of heteroatom nucleophiles linked to a π-system is one of the well recognized chemistry for the construction of numerous heterocyclic cores. Though the rudimentary aspects of this transformation are reviewed by several groups in different timeline, a holistic view on regiochemistry of such reactions went largely overlooked. Hence, this account emphasizes the gold catalyzed regioselective cycloisomerization of structurally distinctive π-connected hetero-nucleophiles leading to different heterocycles documented in the last two decades. From an application perspective, this account also highlights those methodologies which find a role in the total synthesis of natural products. Wherever appropriate, mechanistic details and contributing factors for selectivity are also discussed.

Crystal structures of 1-(4-chloro-phen-yl)-4-(4-methyl-phen-yl)-2,5-dioxo-1,2,5,6,7,8-hexa-hydro-quinoline-3-carb-oxy-lic acid and 4-(4-meth-oxy-phen-yl)-1-(4-methyl-phen-yl)-2,5-dioxo-1,2,5,6,7,8-hexa-hydro-quinoline-3-carbo-nitrile

In the title compounds C23H21ClN2O3 [I, namely 1-(4-chloro-phen-yl)-4-(4-methyl-phen-yl)-3,8-dioxo-1,2,5,6,7,8-hexa-hydro-quine-3-carb-oxy-lic acid] and C24H22N2O3 [II, namely 4-(4-meth-oxy-phen-yl)-1-(4-methyl-phen-yl)-2,5-dioxo-1,2,5,6,7,8-hexa-hydro-quinoline-3-carbo-nitrile], each of the cyclo-hexene and di-hydro-pyridine rings of the 1,2,5,6,7,8-hexa-hydro-quinoline moieties adopts a twisted-boat conformation. The asymmetric units of both compounds I and II consist of two independent mol-ecules (A and B). In II A, three carbon atoms of the cyclo-hexene ring are disordered over two sets of sites in a 0.670 (11):0.330 (11) occupancy ratio. In the crystal of I, mol-ecules are linked through classical N-H⋯O hydrogen bonds, forming inversion dimers with an R 2 2(8) ring motif and with their mol-ecular planes parallel to the crystallographic (020) plane. Non-classical C-H⋯O hydrogen-bonding inter-actions connect the dimers, resulting in a three-dimensional network. In the crystal of II, mol-ecules are linked by C-H⋯N, C-H⋯O and C-H⋯π inter-actions, forming a three-dimensional network.

Organocatalytic Combinatorial Synthesis of Quinazoline, Quinoxaline and Bis(indolyl)methanes

AIMS AND OBJECTIVE

An efficient and practical procedure for the synthesis of heterocyclic compounds such as quinazolines, quinoxalines and bis(indolyl)methanes was developed using 3,5-bis(trifluoromethyl) phenyl ammonium hexafluorophosphate (BFPHP) as a novel organocatalyst.

MATERIALS AND METHODS

All of the obtained products are known compounds and identified by IR, 1HNMR, 13CNMR and melting points.

RESULT

Various products were obtained in good to excellent yields under reaction conditions.

CONCLUSION

The BFPHP organocatalyst demonstrates a novel class of non-asymmetric organocatalysts, which has gained much attention in green chemistry.

Development of an efficient, one-pot, multicomponent protocol for synthesis of 8-hydroxy-4-phenyl-1,2-dihydroquinoline derivatives

A one-pot quick and efficient multicomponent reaction has been developed for the synthesis of a new series of functionalized 8-hydroxy-4-phenyl-1,2-dihydroquinoline derivatives using 30 mol% ammonium acetate in ethanol as solvent. This economical protocol run smoothly to give variety of quinoline derivatives in 55% to 98% yield from inexpensive reagents and catalyst in mild reaction conditions. Various spectroscopic techniques like FTIR, 1H NMR and 13C NMR, MALDI-TOF-MS, and EI-MS were used to study and confirm their structure.

Synthesis and antibacterial activity of novel arylbis(indol-3-yl)methane derivatives

A series of new compounds-arylbis(indol-3-yl)methylium derivatives-were synthesized and their antimicrobial activity was evaluated. All the compounds turned out to be highly active, with MIC depending on their structure and the length of N-alkyl residues. The parent triarylmethane compounds possess weaker activity.

Meglumine as a green, efficient and reusable catalyst for synthesis and molecular docking studies of bis(indolyl)methanes as antioxidant agents

An efficient and convenient Meglumine catalyzed procedure for the synthesis of bis(indolyl) methanes at ambient temperature under aqueous conditions in high yields. The catalytic reaction proceeds very smoothly. Clean reaction, ease of product isolation/purification, easily available reactants, metal free and environmentally friendly reaction conditions are the notable advantages of the present methodology. All the entitled compounds were characterized by IR, ¹H, ¹³C NMR, mass spectra and evaluated for their antioxidant (DPPH, H₂O₂ and NO scavenging methods). They exhibited potent in vitro antioxidant activity dose-dependently. The binding interactions and molecular docking studies for entitled compounds were studied against 3MNG protein. 4d exhibited marked binding affinity with excellent docking score of -7.6 K.cal/mol and emerged as a lead compound.

Catalyst-free visible-light-induced condensation to synthesize bis(indolyl)methanes and biological activity evaluation of them as potent human carboxylesterase 2 inhibitors

A mild strategy for visible-light-induced synthesis of bis(indolyl)methanes was developed using aromatic aldehydes and indole as substrates. This reaction could be performed at room temperature under catalyst- and additive-free conditions to synthesize a series of bis(indolyl)methanes in good to excellent yields. In addition, all synthesized bis(indolyl)methanes together with β-substituted indole derivatives synthesized according to our previous work, were evaluated for their inhibitory effect against human carboxylesterase (CES1 and CES2). Primary structure–activity relationship analysis of all tested compounds showed that the modifications of β-substituted indole at the β-site with another indolyl group led to a significant enhancement of the inhibitory effect on CES2, and the bisindolyl structure is essential for CES2 inhibition. These results demonstrated that these bis(indolyl)methanes are potent and selective CES2 inhibitors, which might be helpful for medicinal chemists to design and develop more potent and selective CES2 inhibitors for biomedical applications.

Bis(indolyl)methanes were synthesized by a green protocol. Primary structure–activity relationship analysis showed that the bisindolyl structure is essential for CES2 inhibition.

B(C6F5)3-catalyzed Markovnikov addition of indoles to aryl alkynes: an approach toward bis(indolyl)alkanes

The first example of the metal- and solvent-free B(C6F5)3-catalyzed Markovnikov addition of indoles to aryl alkynes was disclosed. Both N-H and N-protected indoles were tolerated, leading to a wide spectrum of versatile bis(indolyl)alkanes in moderate to good yields with high regioselectivities.

The crystal structure of 6-chloro-2,4-diphenylquinoline

C21H14ClN, orthorhombic, Pca21 (No. 29), a = 7.6860(5) Å, b = 10.1610(5) Å, c = 19.8990(5) Å, V = 1554.1(13) Å3, Z = 4, R gt (F) = 0.0318, wR ref (F 2 ) = 0.0783, T = 100(2) K.

Anticancer activity of synthetic bis(indolyl)methane-ortho-biaryls against human cervical cancer (HeLa) cells

Bis(indolyl)methane appended biaryls were designed, synthesized and evaluated in human cervical cancer cell lines (HeLa) for their anticancer activities and compared against normal rat cardiac myoblasts (H9C2) cells. Compounds 1-12 were synthesized, with variations in one of the phenyl unit, in a single step by condensation of biaryl-2-carbaldehydes with indole in the presence of para-toluenesulfonic acid. Compound 1 exhibited a GI50 value of 11.00 ± 0.707 μM and the derivatives, compounds 4 and 11 showed a GI50 value of 8.33 ± 0.416 μM and 9.13 ± 0.177 μM respectively in HeLa cells and was found to be non-toxic to H9C2 cells up to 20 μM. Furthermore, compounds 1, 4 and 11 induced caspase dependent cellular apoptosis in a concentration-dependent manner, reduced mitochondrial membrane potential, inhibited the cell migration and downregulated the production of MMP-2 and MMP-9 in HeLa cells.

Non-redox metal ion promoted oxidative coupling of indoles with olefins by the palladium(ii) acetate catalyst through dioxygen activation: experimental results with DFT calculations

Non-redox metal ions can sharply improve the Pd(ii)-catalyzed oxidative coupling of indoles with acrylates, leading to one-step synthesis of bis(indolyl)methane derivatives.

Cu(OTf)2 catalyzed three component strategy for the synthesis of thienopyridine containing spirooxindoles and their cytotoxic evaluation

Compound 5v docked in caspase-3 (−10.5 kcal mol⁻¹).

In-vitro antimicrobial, antibiofilm, cytotoxic, antifeedant and larvicidal properties of novel quinone isolated from Aegle marmelos (Linn.) Correa

Background

Plant metabolites have wide applications and have the potential to cure different diseases caused by microorganisms. The aim of the study was to evaluate the antimicrobial, antibiofilm, cytotoxic, antifeedant and larvicidal properties of novel quinine isolated from Aegle marmelos (Linn.) Correa.

Methods

A compound was obtained by eluting the crude extract, using varying concentrations of the solvents by the chromatographic purification. Broth micro dilution method was used to assess the antimicrobial activity and anticancer study was evaluated using MTT assay. Larvicidal activity was studied using leaf disc no-choice method.

Results

Based on the IR, ¹³C NMR and ¹H NMR spectral data, the compounds were identified as quinone related antibiotic. It exhibited significant activity against Gram positive and Gram negative bacteria. The lowest Minimum Inhibitory Concentration (MIC) of the compound against Bacillus subtilis and Staphylococcus aureus was 100 and 75 μg mL⁻¹ respectively. Against Escherichia coli and Pseudomonas aeruginosa it exhibited MIC value of 25 μg mL⁻¹. The MIC of the compound against Aspergillus niger, A. clavatus, Penicillium roqueforti was 20 μg mL⁻¹ and that against Fusarium oxysporum (20 μg mL⁻¹), A. oryzae (40 μg mL⁻¹), and Candida albicans (60 μg mL⁻¹), respectively. It showed effective antibiofilm activity against E. coli, S. typhii and P. aeroginosa at 8 μg mL⁻¹ and did not exhibit considerable cytotoxic activity against Vero and HEP2 cell lines. Additionally, the compound documented significant antifeedant and larvicidal activities against Helicoverpa armigera and Spodoptera litura at 125, 250, 500 and 1000 ppm concentrations.

Conclusion

The results concluded that the compound can be evaluated further in industrial applications and also an agent to prepare botanical new pesticide formulations.

Synthesis, and the antioxidant, neuroprotective and P-glycoprotein induction activity of 4-arylquinoline-2-carboxylates

An efficient synthesis of 4-arylquinoline-2-carboxylates and their antioxidant, neuroprotective and P-glycoprotein induction activity have been described.

Palladium-catalyzed synthesis of polysubstituted quinolines from 2-amino aromatic ketones and alkynes

A palladium-catalyzed one-pot method for the synthesis of quinolines from commercial or readily available 2-amino aromatic ketones and alkynes is reported for the first time.

Recent advances in the synthesis of quinolines: a review

This review article gives information about the recent advances in the synthesis of quinoline derivatives by various eco-friendly, green and clean protocols.