An efficient one-pot synthesis, structure, antimicrobial and antioxidant investigations of some novel quinolyldibenzo[b,e][1,4]diazepinones

Isocyanide-Based Multicomponent Reactions in Water: Advanced Green Tools for the Synthesis of Heterocyclic Compounds

Reaction rate acceleration using green methods is an intriguing area of research for chemists. In this regard, water as a "green solvent" plays a crucial role in the acceleration of some organic transformations and reveals exclusive selectivity and reactivity in comparison with conventional organic solvents. In particular, multicomponent reactions (MCRs) as sustainable tools lead to the rapid generation of small-molecule libraries in water and aqueous media due to the prominent role of the hydrophobic effect. MCRs, as diversity-oriented synthesis (DOS) methods, have great efficiency with simple operations, atom, pot, and step economy synthesis, and mechanistic beauty. Among diverse classes of MCRs, isocyanide-based multicomponent reactions (I-MCRs), as sustainable and versatile reactions, have gained considerable attention in the synthesis of diverse heterocycle rings, especially in drug design because of the peculiar nature of isocyanide as a particular active reactant. I-MCRs that are performed in water are mild, environmentally friendly, and easily controlled, and have a reduced number of workup, purification, and extraction steps, which fit well with the advantages of "green" chemistry. Performing these powerful organic transformations in water and aqueous media is accompanied by acceleration owing to negative activation volumes, which originate from connecting several reactants together to generate a single product. It should be noted that the combination of MCR strategy and aqueous phase reaction is of growing interest for the development of sustainable synthetic techniques in organic conversions. However, an exclusive account focusing on the recent progress in eco-friendly I-MCRs for the construction of heterocycles in water and aqueous media is particularly lacking. This review highlights the progress of various kinds of I-MCRs in water and aqueous media as benign methods for the efficient construction of vital heterocyclic scaffolds, with a critical discussion of the subject in the period 2000-2021. We hope that this themed collection will be of interest and beneficial for organic and pharmaceutical chemists and will inspire more reaction development in this fascinating field.

Synthesis of tetracyclic pyrido-fused dibenzodiazepines via a catalyst-free cascade reaction

An efficient, eco-friendly protocol has been described for the chemoselective synthesis of tetracyclic pyrido-fused dibenzodiazepines derivatives via catalyst-free, three-component reaction of dimedone, 1,2-diamines, 3-formylchromones, and malononitrile. The significant advantages of this cascade approach are to create two new rings and four new σ bonds containing three C-N and one C-C bond, as well as the breakdown of a C-O bond.

Multicomponent reactions as a potent tool for the synthesis of benzodiazepines

Benzodiazepines (BZDs), a diverse class of benzofused seven-membered N-heterocycles, display essential pharmacological properties and play vital roles in some biochemical processes. They have mainly been prescribed as potential therapeutic agents, which interestingly represent various biological activities such as anticancer, anxiolytic, antipsychotic, anticonvulsant, antituberculosis, muscle relaxant, and antimicrobial activities. The extensive biological activities of BZDs in various fields have encouraged medicinal chemists to discover and design novel BZD-based scaffolds as potential therapeutic candidates with the favorite biological activity through an efficient protocol. Although certainly valuable and important, conventional synthetic routes to these bicyclic benzene compounds contain methodologies often requiring multistep procedures, which suffer from waste materials generation and lack of sustainability. By contrast, multicomponent reactions (MCRs) have recently advanced as a green synthetic strategy for synthesizing BZDs with the desired scope. In this regard, MCRs, especially Ugi and Ugi-type reactions, efficiently and conveniently supply various complex synthons, which can easily be converted to the BZDs via suitable post-transformations. Also, MCRs, especially Mannich-type reactions, provide speedy and economic approaches for the one-pot and one-step synthesis of BZDs. As a result, various functionalized-BZDs have been achieved by developing mild, efficient, and high-yielding MCR protocols. This review covers all aspects of the synthesis of BZDs with a particular focus on the MCRs as well as the mechanism chemistry of synthetic protocols. The present manuscript opens a new avenue for organic, medicinal, and industrial chemists to design safe, environmentally benign, and economical methods for the synthesis of new and known BZDs.

New pyrazolyl-dibenzo[b,e][1,4]diazepinones: room temperature one-pot synthesis and biological evaluation

Several new (5-aryloxy-pyrazolyl)- and (5-aryl/olefin-sulfanyl-pyrazolyl)-dibenzo[b,e] [1,4] diazepinone scaffolds have been synthesized, by assembling 5-substituted 3-methyl-1-phenyl-pyrazole-4-carbaldehydes of varied nature with different cyclic diketones and aromatic diamines successfully in the presence of indium chloride in acetonitrile, at room temperature. Desired products are excellent in the purity and isolated without chromatography. All new structures are confirmed, on the basis of single-crystal X-ray diffraction data of representative 29e. Compounds reported in the present work revealed good antioxidant, antimicrobial and antiproliferative activities with promising FRAP (ferric reducing antioxidant power), bacterial resistance and human solid tumor cell growth inhibitory values, respectively. Compounds 25c and 29e, overall, registered good to moderate activity against A549 (lung), HeLa (cervix), SW1573 (lung) T-47D (breast) and WiDr (colon) cell lines, with GI₅₀ values in the 2.6-5.1 μM and 1.8-7.5 μM ranges, respectively. Molecular docking was carried out to elucidate the binding modes of the compounds (25c, 29e) to topoisomerase I and II.

Desymmetrization of Cyclopropenes via the Potassium-Templated Diastereoselective 7- exo- trig Cycloaddition of Tethered Amino Alcohols toward Enantiopure Cyclopropane-Fused Oxazepanones with Antimycobacterial Activity

A strain-release-driven, cation-templated intramolecular nucleophilic addition of tethered alkoxides to prochiral cyclopropenes is described. Employment of chiral β- and γ-amino alkoxides allowed for highly diastereoselective assembly of a small series of enantiopure cyclopropane-fused oxazepanones. It was shown that the chiral center at C-4 plays a crucial role in controlling desymmetrization of the cyclopropenyl moiety, instigated by a profound potassium-templated effect. The preliminary biological activities of the new cyclopropane-fused medium heterocycles against Gram-positive bacteria, Gram-negative bacteria, mycobacteria, cancer cells, and fungus were evaluated.

One pot synthesis, antimicrobial and antioxidant activities of fused uracils: pyrimidodiazepines, lumazines, triazolouracil and xanthines

Background

Uracil derivatives have a great attraction because they play an important role in pharmacological activities. Pyrimidodiazepines, lumazines, triazolopyrimidines and xanthines have significant wide spectrum activities including anticancer, antiviral as well as antimicrobial activities.

Results

A newly synthesized compounds pyrimido[4,5-b][1, 4]diazepines 5a–e, 6a–d, lumazines 7a–d, triazolo[4,5-d]pyrimidine 8 and xanthines 9, 10 was prepared in a good yields. The antimicrobial and antioxidant activities of compounds 5a, 5b, 6a, 6d and 8 exhibited a wide range activity against the pathogenic tested microbes (Staphylococcus aureus, Bacillus subtilis, Pseudomonas aeruginosa, Candida albicans, and Saccharomyces cerevisiae). Compound 8 showed activity against the fungus Aspergillus niger. The highest antioxidant activity was noticed for compound 5a.

Conclusions

A series of novel pyrimido[4,5-b][1, 4]diazepines 5a–e, 6a–d, lumazines 7a–d, triazolo[4,5-d]pyrimidine 8 and xanthines 9, 10 was prepared from 5,6-diamino-1-(2-chlorobenzyl)uracil 3 in good yields. Compounds 5a–e, 6a–d were prepared by sequential manipulation of 3 with α,β-unsaturated ketones. Lumazines 7a–d were obtained from 3 by treatment with phenacyl bromides in the presence of TEA. Compound 8 was prepared by treatment of 3 with HNO₂, while xanthines 9, 10 were obtained from 3 by consecutive acetylation then intramolecular cyclodehydration or heating with malononitrile under solvent-free condition. The antimicrobial and antioxidant activity of this series was evaluated in vitro and they showed either weak or moderate activities.Graphical abstract

A catalyst- and solvent-free multicomponent synthesis and docking study of some new antiproliferative N5-allyl-quinolylpyrido[2,3-b][1,4]benzodiazepinone precursors

Heterocycles of this series resemble MDM2 inhibitors.

Regioselective synthesis, antimicrobial evaluation and theoretical studies of 2-styryl quinolines

2-Styryl quinolines (9a-l) have been synthesized regioselectively from 2-methyl-quinoline by using NaOAc in water acetic acid binary solvents and evaluated for their antibacterial activity against both Gram-positive and Gram-negative strains. Among these, the compounds 12 and 8 were found to be active against both bacterial strains. Compounds 9b, 9f, 9g, 9i, 9j and 9k were the most active among the series exhibiting MIC values ranging between 1.9 and 31.2 μg ml(-1) against different bacterial strains. Compounds 9j and 9k were found to be as potent as the standard drug ciprofloxacin against Micrococcus luteus, Klebsiella planticola and Staphylococcus aureus. In addition, the compounds showed bactericidal activity; compound 9j was found to be better than ciprofloxacin, with an MBC value of 0.9 μg ml(-1) against both M. luteus and K. planticola. The compounds also inhibited biofilm formation, and compound 9j was found to be equipotent to erythromycin against M. luteus and S. aureus MLS16. Further, theoretical studies such as those on druggable properties and PMI plot have been carried out.

Covalent Modification of Organo-Functionalized Graphene Oxide and its Scope as Catalyst for One-Pot Pyrazolo-Pyranopyrimidine Derivatives

The surface of graphene oxide (GO) was modified using [3‐(2‐aminoethylamino)propyl]trimethoxysilane (diamine), which exhibited excellent catalytic activity for one‐pot multicomponent reactions. The newly synthesized material was fully characterized by various instrumental techniques including Fourier‐transfer infrared (FTIR) and Raman spectroscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The instrumental analysis confirmed the successful grafting of organic amine functional groups onto the graphene oxide surface. The diamine‐functionalized GO proved to be an excellent catalyst for the synthesis of pyrazolo‐pyranopyrimidine derivatives with 93 % yield and high selectivity. The catalytic activity almost remained unaltered up to three cycles. The newly synthesized pyrazolo‐pyranopyrimidine derivatives have potential use as scaffolds in designing new pharmaceutical products.

Synthesis, crystal structures and docking studies of 2,7-diphenyl-1,4-diazepan-5-one derivatives

Background

1,4-Diazepine derivatives are the seven membered, nitrogen containing heterocyclic ring systems possessing a wide range of therapeutic applications. 1,4-Diazepines attracted the attention of chemists and druggists due to their biological and medicinal properties, such as antimicrobial, anti-HIV and anticancer activities. Herein, we report the preparation, crystal structure determined by X-ray crystallographic methods and docking of the molecules with the potential target protein NS5B RNA polymerase.

Results

The crystal structures and conformational studies of 1,4-diazepine [t-3, t-6-dimethyl-r-2,c-7-diphenyl-1,4-diazepan-5-one(DIAZ1)] and its nitroso derivative [t-3, t-6-dimethyl-1-nitroso-r-2,c-7-diphenyl-1,4-diazepan-5-one(DIAZ2)] are reported. The analyses of the molecules reveal that the seven membered diazepine ring systems adopt chair and boat conformations in compounds DIAZ1 & DIAZ2, respectively. In DIAZ2, the oxygen O2A is disordered over two positions with the refined occupancies of 0.792(7): 0.208(7) in the nitroso group. In both DIAZ1 & DIAZ2, the symmetry related molecules form a hetero/homo-dimer through N-H…O hydrogen bonds.

Conclusion

In this study, the crystal structures of two new 1,4-diazepines, namely t-3, t-6-dimethyl-r-2,c-7-diphenyl-1,4-diazepan-5-one and t-3, t-6-dimethyl-1-nitroso-r-2,c-7-diphenyl-1,4-diazepan-5-one were synthesized and characterized by X-ray crystallographic methods. The docking studies show that the compounds inhibit at the active site of the target protein and can be utilized as potential drug molecules. In both the compounds, N-H…O hydrogen bonds lead to dimer formation. In DIAZ2, additionally a couple of C-H…O interactions are noted between the molecules.

Graphical Abstract

Structure and docking studies of 1,4-diazapine derivatives.

Electronic supplementary material

The online version of this article (doi:10.1186/s13065-015-0094-3) contains supplementary material, which is available to authorized users.

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An efficient synthesis of new caffeine-based chalcones, pyrazolines and pyrazolo[3,4-b][1,4]diazepines as potential antimalarial, antitrypanosomal and antileishmanial agents

A new series of chalcones 5a-f were synthesized from caffeine-based aldehyde 3 and substituted acetophenones 4a-f. Treatment of compounds 5a-f with hydrazine hydrate led to pyrazolines 6a-f, and their subsequent reaction with acetic anhydride or formic acid afforded the corresponding N-substituted pyrazolines 7a-f and 8a-f respectively. Additionally, the regioselective cyclocondensation reaction of chalcones 5a-f with 4,5-diaminopyrazole 9 afforded the diazepine derivatives 10a-f. Synthesis of the above novel compounds was carried out through a simple procedure involving an easy work-up and mild reaction conditions. In vitro antimalarial activity against Plasmodium falciparum was evaluated for the obtained compounds. Among of them, just pirazoline 6a showed an outstanding growth inhibition percentage 85.2 ± 5.4%, while diazepines 10a-f showed remarkable growth inhibitions in the range of 80.3 ± 13.5 to 94.2 ± 0.2% when were tested at 20 μg/mL. Compounds 5b, 5e, 7c and 7f showed remarkable activities against Leishmania panamensis with growth inhibition of 88.3 ± 1.5, 82.6 ± 2.2, 82.8 ± 1.7 and 87.6 ± 0.5% respectively, at 20 μg/mL. In vitro assays against Trypanozoma cruzi showed that pyrazoline 6d displayed a growth inhibition of 61.9 ± 7.8% at 20 μg/mL while chalcone 5f was considered especially active with a growth inhibition of 9.7 ± 1.5% for a very low concentration of 1.0 μg/mL.

Synthesis of novel thiazole-based 8,9-dihydro-7H-pyrimido[4,5-b][1,4]diazepines as potential antitumor and antifungal agents

A new series of novel thiazole-based 8,9-dihydro-7H-pyrimido[4,5-b][1,4]diazepines 6a-g and 7a-g were obtained with high regioselectivity from the reaction of triamino- or tetraaminopyrimidines 4 and 5 with α,β-unsaturated carbonyl compounds 3a-g based on 2,4-dichlorothiazol-5-carbaldehyde 1. Twelve of the synthesized compounds were selected and tested by US National Cancer Institute (NCI) for their antitumor activity against 60 different human tumor cell lines. Compounds 7d and 7g showed important GI50 ranges of 1.28-2.98 μM and 0.35-2.78 μM respectively under in vitro assays. In addition, 6a-g and 7a-g were tested for antifungal properties against the clinical important fungi Candida albicans and Cryptococcus neoformans. Although these compounds showed moderate activities against C. albicans, the 2-amino derivatives 7a-g and mainly 7a and 7b, showed high activity against standardized and clinical isolates of C. neoformans with MIC50 = 7.8-31.2 μg/mL, MIC80 = 15.6-31.2 μg/mL and MIC100 = 15.6-62.5 μg/mL. In addition, since both compounds were fungicide rather than fungistatic these thiazole-based 8,9-dihydro-7H-pyrimido[4,5-b][1,4]diazepines appear as good candidates for further development not only as antifungal but also as antitumor drugs.

Quinoline and quinolones: promising scaffolds for future antimycobacterial agents

Tuberculosis (TB) is still a major health concern worldwide. The increasing incidences of multi-drug-resistant tuberculosis (MDR-TB) necessitate the development of new anti-TB drugs acting via novel mode of action. The search of newer drugs for TB led to the identification of several quinoline-based antimycobacterial agents against both the drug-sensitive and MDR-TB. These agents have been designed by substituting quinoline scaffold with diverse chemical functionalities as well as by modifying quinoline/quinolone-based antibacterial drugs. Several of quinoline/quinolone derivatives displayed excellent antimycobacterial activity and were found free of cytotoxicity. This review highlights the critical aspects of design and structure-activity relationship of quinoline- and quinolone-based antimycobacterial agents.

(8RS)-4-Amino-6-(4-chlorophenyl)-8-(2,4-dichlorothiazol-5-yl)-8,9-dihydro-7H-pyrimido[4,5-b][1,4]diazepine N,N-dimethylformamide monosolvate: sheets built from N-H···N and C-H···O hydrogen bonds

In the title compound, C16H11Cl3N6S·C3H7NO, the seven-membered ring adopts a conformation which is close to the twist-boat form. The molecular components are linked into sheets by a combination of two N-H···N hydrogen bonds and two C-H···O hydrogen bonds. Comparisons are made with other aminopyrimidine derivatives.