A general method for the metal-free, regioselective, remote C-H halogenation of 8-substituted quinolines

Iron-Catalyzed Regioselective Remote C(sp2)-H Carboxylation of Naphthyl and Quinoline Amides

Iron(III)-catalyzed regioselective direct remote C-H carboxylation of naphthyl and quinoline amides was developed using CBr₄ and alcohol. The reaction involves a radical pathway using a coordination activation strategy and single electron transfer process. The use of sustainable iron catalysis, selectivity, and the substrate scope are the important practical features.

Visible Light-Promoted Photocatalytic C-5 Carboxylation of 8-Aminoquinoline Amides and Sulfonamides via a Single Electron Transfer Pathway

An efficient photocatalytic method was developed for the remote C5-H bond carboxylation of 8-aminoquinoline amide and sulfonamide derivatives. This methodology uses in situ generated ^•CBr₃ radical as a carboxylation agent with alcohol and is further extended to a variety of arenes and heteroarenes to synthesize the desired carboxylated product in moderate-to-good yields. The reaction proceeding through a single electron transfer pathway was established by a control experiment, and a butylated hydroxytoluene-trapped aryl radical cation intermediate in high-resolution mass spectrometry was identified.

Remarkable electronic effect on the total stereoselectivity of the cycloaddition reaction of arylnitrile oxides with pyrrol-2-one derivatives

The regiospecific 1,3-dipolar cycloaddition of 1,5-dihydropyrrol-2-one and arylnitrile oxides derivatives have been investigated. The asymmetric induction expected by the chiral centre of the 5-hydroxy-3-methyl-1,5-dihydropyrrol-2-one derivatives was very effective, single diastereoisomers anti-3 was formed. The diastereoselectivity was linked to the destabilization of the syn transition state as a result of the electrostatic repulsion between the hydroxy group of the dihydropyrrol-2-one derivatives and the atom oxygen of the dipole.

Design, synthesis and biological profile of heterocyclic benzimidazole analogues as prospective antimicrobial and antiproliferative agents

Background

Nitrogen containing heterocycles are widely used and investigated by pharmaceutical industry, as they are important in discovery and designing of new drug molecules. Drugs with a benzimidazole nucleus possess exclusive structural features and electron-rich atmosphere, which enable them to bind to a number of biologically important targets and result in a wide range of activities. This has served as the basis of the present study whereby new scaffolds with benzimidazole moiety were designed and synthesized.

Methods

The structures of synthesized compounds were confirmed by physicochemical and spectral means. The synthesized compounds were screened for their antimicrobial and antiproliferative activities by tube dilution and Sulforhodamine B (SRB) assays, respectively.

Results and conclusion

The in vitro biological screening results revealed that compound Z24 exhibited promising antimicrobial and anticancer activities which are comparable to standards.

Design, Synthesis, and Cytotoxic Activity of 3-Aryl-N-hydroxy-2-(sulfonamido)propanamides in HepG2, HT-1080, KB, and MCF-7 Cells

A new series of (sulfonamido)propanamides (6a1-6a13, 6b1-6b15, 7c1-7c5, 6d1-6d5, 6e1-6e6) was designed and synthesized. All the synthesized compounds were characterized by NMR and mass spectrometry. The target compounds were evaluated for their in vitro cytotoxic activity against hepatocellular carcinoma (HepG2), fibrosarcoma (HT-1080), mouth epidermal carcinoma (KB), and breast adenocarcinoma (MCF-7) cell lines with the sulforhodamine B (SRB) assay, with gemcitabine and mitomycin C as positive controls. Most of these compounds exhibit a more potent cytotoxic effect than the positive control group on various cancer cell lines and the most potent compound, 6a7, shows the IC₅₀ values of 29.78±0.516 μm, 30.70±0.61 μm, and 64.89±3.09 μm in HepG2, HT-1080, KB, and MCF-7 cell lines, respectively. Thus, these compounds with potent cytotoxic activity have potential for development as new chemotherapy agents.

In-silico design, synthesis, ADMET studies and biological evaluation of novel derivatives of Chlorogenic acid against Urease protein and H. Pylori bacterium

Background

Plants have always played important role in treating human and animal diseases as a therapeutic agent for traditional medicine. Through extensive research throughout the world, potential of natural products have been identified to control the over activity of many enzymes. In-silico screening a library of chlorogenic acid derivatives highlighted some novel compounds which were found effective against urease enzyme and cancer causing H. Pylori bacterium. Selected top ligands possessing minimum binding energy and good docking score were synthesized in wet lab by suitable procedure and evaluated for urease enzyme inhibition and free radical scavenging property. Synthetic scheme includes three step reactions i. e protection of hydroxyl group of quinic acid part of chlorogenic acid with lactonisation process, anilide formation by reaction with substituted anilines followed by extraction with ethyl acetate under vacuum and deprotection of hydroxyl groups by treatment with hydrochloric acid.

Results

In-vitro results of the series concluded that compounds C4a, C4d and C4b (IC₅₀ 11.01 ± 0.013, 13.8 ± 0.041 and 15.86 ± 0.004 µM respectively in urease inhibition and 5.10 ± 0.018, 5.34 ± 0.007 and 6.01 ± 0.005 µM in antioxidant property against DPPH) were found to be significantly potent with excellent dock score − 10.091, − 10.603, − 9.833 and binding energy − 62.674, − 63.352, 56.267 kg/mol as compared to standard drugs thiourea and acetohydroxamic acid (− 3.459, − 3.049 and − 21.156 kJ/mol and − 17.454 kJ/mol) whereas compounds C4c, C4(e, h) exhibited moderate in vivo activity when compared to standard.

Conclusions

Selected candidates from the outcome of in vitro urease inhibitory were further examined for anti-H. Pylori activity by well diffusion method against H. pylori bacterium (DSM 4867). Compound C4a showed significant anti-H. Pylori activity with zone of inhibition 10.00 ± 0.00 mm and MIC value 500 μg/mL as compared to standard drug acetohydroxamic acid having zone of inhibition 9.00 ± 0.50 mm and MIC 1000 μg/mL. Molecular docking studies also showed that compounds show strong inhibition by forming strong hydrogen bonding interactions with residues of pocket site in target protein. Hence, the present investigation studies will provide a new vision for the discovery of potent agents against H. Pylori and urease associated diseases.

Lead optimization for promising monoamine oxidase inhibitor from eugenol for the treatment of neurological disorder: synthesis and in silico based study

Natural based inhibitors of monoamine oxidase are promising drug candidates for the treatment of several neurodegenerative and neuropsychological disorders including depression, anxiety, Parkinson’s disease and Alzheimer’s disease. In the present study we designed and synthesized the eugenol based derivatives and investigated them for human MAO inhibitory potential as promising candidates for therapeutics of neurological disorders. Moreover, radical scavenging activity of designed derivatives was tested by and H₂O₂ and DPPH scavenging methods. Eugenol based derivatives were designed and synthesized for human MAO inhibitory action. The in silico and in vitro models were utilized for the evaluation of hMAO inhibition. The insight into molecular interactions among the compounds and both hMAO-A and hMAO-B active site was achieved by molecular docking studies. The two spectrophotometric titrations techniques were used to evaluate antioxidant potential. Compounds 5b and 16 were found as most active hMAO-A inhibitors with IC₅₀ values of 5.989 ± 0.007 µM and 7.348 ± 0.027 µM respectively, through an appreciable selectivity index value of 0.19 and 0.14 respectively. In case of hMAO-B inhibition compounds 13a and 13b were found as most active hMAO-B inhibitors with IC₅₀ values of 7.494 ± 0.014 µM and 9.183 ± 0.034 µM receptively and outstanding value of selectivity index of 5.14 and 5.72 respectively. Radical scavenging assay showed that compounds 5b, 5a, 9b, 9a were active antioxidants. The findings of present study indicated excellent correlation among dry lab and wet lab hMAO inhibitory experiments. Interestingly, the compounds exhibiting better MAO inhibition activity was also appeared as good antioxidant agents.

Efficient Electrocatalysis for the Preparation of (Hetero)aryl Chlorides and Vinyl Chloride with 1,2-Dichloroethane

Although the application of 1,2-dichloroethane (DCE) as a chlorinating reagent in organic synthesis with the concomitant release of vinyl chloride as a useful byproduct is a fantastic idea, it still presents a tremendous challenge and has not yet been achieved because of the harsh dehydrochlorination conditions and the sluggish C-H chlorination process. Here we report a bifunctional electrocatalysis strategy for the catalytic dehydrochlorination of DCE at the cathode simultaneously with anodic oxidative aromatic chlorination using the released HCl as the chloride source for the efficient synthesis of value-added (hetero)aryl chlorides. The mildness and practicality of the protocol was further demonstrated by the efficient late-stage chlorination of bioactive molecules.

Iron(III)-Catalyzed Highly Regioselective Halogenation of 8-Amidoquinolines in Water

A simple protocol of iron(III)-catalyzed halogenation of 8-amidoquinolines in water under mild conditions was developed, affording the 5-halogenlated products in good to excellent yields up to 98%. The reaction mechanism most likely involves a single-electron transfer (SET) process.

Design, synthesis and evaluation of novel 3,5-disubstituted benzamide derivatives as allosteric glucokinase activators

Glucokinase (GK) is the key enzyme expressed in β-cells of pancreas and liver hepatocytes and helps in the maintenance of blood glucose levels in normal range. Activators of GK are the novel category of drug candidates which activate GK enzyme allosterically and show their antidiabetic activity. A new series of 3,5-disubstituted benzamide analogues was designed, synthesized and evaluated as GK activators by in vitro assay as well as in silico docking studies followed by evaluation of antihyperglycemic activity in animal model. Amongst the synthesized derivatives, compounds 5c, 5f, 5i, 6c, 6e and 6h displayed excellent in vitro GK activation. Compounds 6c and 6e exhibited highest antihyperglycemic activity in oral glucose tolerance test in animal model. Compound 6e displayed most significant antihyperglycemic activity and comparable to that of standard drug in animal studies. In addition, antihyperglycemic activity of the synthesized molecules was further supported by the in silico docking studies of the synthesized derivatives in the allosteric site of GK protein.

Visible light-induced transformation of aldehydes to esters, carboxylic anhydrides and amides

A transition metal- and organophotocatalyst free synthesis of esters, carboxylic anhydrides and amides from aldehydes induced by visible-light has been reported.

A simple, tandem approach to the construction of pyridine derivatives under metal-free conditions: a one-step synthesis of the monoterpene natural product, (−)-actinidine

(−)-Actinidine, along with various diversely substituted pyridines were synthesized from simple starting materials, including natural products, using a mild and metal-free method.

Microwave-assisted synthesis of quinazolin-4(3H)-ones catalyzed by SbCl3

Antimony(III) trichloride (SbCl3) is an effective catalyst (1 mol%) for the condensation of anthranilic amide with various aldehydes or ketones to quinazolin-4(3H)-one derivatives in good to excellent yields under microwave irradiation. The process is carried out within several minutes under solvent-free conditions. This general methodology has the advantages of simplicity, mild reaction conditions and high yields of products.

Design, synthesis and biological evaluation of 3-(2-aminooxazol-5-yl)-2H-chromen-2-one derivatives

BACKGROUND

In view of wide range of biological activities of oxazole, a new series of oxazole analogues was synthesized and its chemical structures were confirmed by spectral data (Proton/Carbon-NMR, IR, MS etc.). The synthesized oxazole derivatives were screened for their antimicrobial and antiproliferative activities.

RESULTS AND DISCUSSION

The antimicrobial activity was performed against selected fungal and bacterial strains using tube dilution method. The antiproliferative potential was evaluated against human colorectal carcinoma (HCT116) and oestrogen- positive human breast carcinoma (MCF7) cancer cell lines using Sulforhodamine B assay and, results were compared to standard drugs, 5-fluorouracil and tamoxifen, respectively.

CONCLUSION

The performed antimicrobial activity indicated that compounds 3, 5, 6, 8 and 14 showed promising activity against selected microbial species. Antiproliferative screening found compound 14 to be the most potent compound against HCT116 (IC₅₀ = 71.8 µM), whereas Compound 6 was the most potent against MCF7 (IC₅₀ = 74.1 µM). Further, the molecular docking study has been carried to find out the interaction between active oxazole compounds with CDK8 (HCT116) and ER-α (MCF7) proteins indicated that compound 14 and 6 showed good dock score with better potency within the ATP binding pocket and may be used as a lead for rational drug designing of the anticancer molecule.

Hybrid caffeic acid derivatives as monoamine oxidases inhibitors: synthesis, radical scavenging activity, molecular docking studies and in silico ADMET analysis

BACKGROUND

Monoamine oxidase has been implicated in numerous neurological disorders. Although synthetic monoamine oxidase inhibitors (MAOI) have emerged with many side effects, the aspiration of natural based MAOI has greatly increased. As they exhibit fewer side effects and food interaction along with improved neuropharmacological profile.

RESULTS

The in silico design of the caffeic acid derivatives led potent MAO inhibitors with remarkable antioxidant activity. The mechanistic insight of the compounds within the hMAO active site was achieved by molecular docking which led us to be more confident of the possible inhibition of MAO.

CONCLUSIONS

The synthesized eugenol based ester of caffeic acid compound 7 exhibited MAO-A inhibition with IC₅₀ values of 07.03 ± 0.022 µM with good selectivity (SI = 0.291) towards MAO-A. Conversely, two anilides compounds 2 and 1, bearing chloro and nitro group at 2, 4 positions showed MAO-A inhibition with IC₅₀ values of 08.51 ± 0.017 µM and 08.87 ± 0.005 µM, respectively. Only one compound 5 was found as a significant MAO-B inhibitor with the IC₅₀ value of 10.80 ± 0.024 µM. Moreover, compounds 1, 2, 4 and 9 have profoundly appeared as potent antioxidants as evaluated in duel assay by scavenging DPPH and H₂O₂.

A Unified Strategy for the Synthesis of β-Carbolines, γ-Carbolines, and Other Fused Azaheteroaromatics under Mild, Metal-Free Conditions

An efficient, unified approach for the synthesis of β-carbolines, γ-carbolines, and other fused azaheteroaromatics has been realized under metal-free conditions, from propargylic amines and (hetero)aromatic aldehydes. This unified strategy provides β- and γ-carbolines as well as a range of fused azaheteroaromatics with a broad substrate scope and excellent functional group compatibility. The formal synthesis of oxopropalines D and G has been achieved on gram scale (3a), in a one-pot reaction from commercially available materials (previous shortest reported route to 3a was 5 steps). NMR studies of the conversion of imine intermediate 3aa to β-carboline 3a were conducted and revealed that the reaction proceeded through an allene intermediate.

Ruthenium(ii)-catalyzed remote C–H addition of 8 aminoquinoline amide to activated aldehyde

Remote C–H addition of 8-aminoquinoline amides at C-5 position to activated aldehydes have been developed using Ru(ii)-catalyst.

Copper-catalyzed one-pot domino reactions via C–H bond activation: synthesis of 3-aroylquinolines from 2-aminobenzylalcohols and propiophenones under metal–organic framework catalysis

A Cu₂(OBA)₂(BPY) metal–organic framework was utilized as a productive heterogeneous catalyst for the synthesis of 3-aroylquinolines via one-pot domino reactions of 2-aminobenzylalcohols with propiophenones. This Cu-MOF was considerably more active towards the one-pot domino reaction than a series of transition metal salts, as well as nano oxide and MOF-based catalysts. The MOF-based catalyst was reusable without a significant decline in catalytic efficiency. To the best of our knowledge, the transformation of 2-aminobenzylalcohols to 3-aroylquinolines was not previously reported in the literature, and this protocol would be complementary to previous strategies for the synthesis of these valuable heterocycles.

Cu₂(OBA)₂(BPY) metal–organic framework was utilized as a productive heterogeneous catalyst for the synthesis of 3-aroylquinolines via one-pot domino reactions of 2-aminobenzylalcohols with propiophenones.