Hydrazonoyl halides: Useful building blocks for the synthesis of arylazoheterocycles

Reactions and Biological Activities of Hydrazonoyl Halides

This review covers the literature information on the chemistry of hydrazonoyl halides with different substrates to give heterocyclic compounds. From the foregoing survey, it seems this provides a useful and convenient strategy for the synthesis of numerous heterocyclic derivatives. The subject of such reactions is still ongoing and undoubtedly will provide new fused functionalized compounds of both industrial and biological interest. A literature survey revealed that a great deal of interest has been focused on the synthesis of functionalized heterocyclic compounds due to their wide range of biological activities, such as contact dermatitis, anthelmintic, antiviral, antimicrobial, herbicidal, and anti-cancer. On the other hand, hydrazonoyl halides are interesting synthons for valuable bioactive heterocyclic compounds. The reaction of hydrazonoyl halides with various types of substrates gave a huge number of different heterocyclic systems. In this review, we collected all reactions of hydrazonoyl halides with different moieties and classified them as aryl diazo of monoheterocycles, aryldiazo of 5,5-bis-heterocycles, aryldiazo of 5,6-bis-heterocycles, aryldiazo of 6,6-bis-heterocycles, aryldiazo of 5,5,6-tri-heterocycles, aryldiazo of 5,6,6-tri-heterocycles, aryldiazo of 6,6,6-tri-heterocycles, hetero annulation of bisheterocycles, hetero annulation of tri-heterocycles, hetero-annulation of tetra-heterocycles, synthesis of spiro-heterocycles, heterocyclic ring transformations, and 1,3-dipolar cycloaddition reactions catalyzed by transition metals using hydrazonoyl halides as substrates.Most reaction types have been successfully applied and used in the production of biologically active compounds. The aim of the present survey is to consider in the reader the opportunity interactions and biological activities of hydrazonoyl halides. The information of several artificial paths and varied physics-chemical factors of such heterocycles made a special consideration of chemists in different fields to yield a combinatorial library and carry out thorough efforts in the search for hydrazonoyl halides.

The (E, Z) Isomerization of C-methoxycarbonyl-N-aryl Chlorohydrazones

Since chlorohydrazones are planar molecules, it is in principle possible to distinguish between their E and Z stereoisomers. Chlorohydrazones are known to preferentially assume the Z configuration around the C=N double bond, and their (E, Z) isomerization is almost suppressed at room temperature. The lack, or rather the difficulty, of such an isomerization has been conveniently addressed by the in-depth theoretical study of seven C-methoxycarbonyl-N-aryl chlorohydrazones (aryl = phenyl, 4-chlorophenyl, 4-bromophenyl, 4-iodophenyl, 2-chlorophenyl, 2-bromophenyl, and 2-iodophenyl). DFT ωB97M-D4/cc-pVTZ calculations of these C-methoxycarbonyl-N-aryl chlorohydrazones, supported by the XRD determination of the molecular structure, provided a complete picture of the isomerization processes in the studied compounds. The analysis of the energetics, molecular geometry, and electronic structure (the latter in the framework of the Quantum Theory of Atoms In Molecules) showed that the Z isomers are thermodynamically favored because, within the low-energy planar isomers with extensive π conjugation, the electrostatic interactions between the dipoles of the C–O, C–Cl, and N–H bonds overcome the stabilization induced by the N–H ··· O bond present in the E isomers. We confirmed that the (E, Z) isomerization occurs by the umklapp mechanism, in which the –NHAr moiety rotates in the molecular plane towards a linear C=N–N configuration and then proceeds to the other isomer. The (E, Z) isomerization is very slow at room temperature because the umklapp interconversion has high barriers (≈110 kJ/mol) despite the extended π electron delocalization present in the transition state.

Synthesis and biological evaluation of new 1,3,4-thiadiazole derivatives as potent antimicrobial agents

A series of 1,3,4-thiadiazole derivatives were designed and synthesized using N-(4-nitrophenyl)acetohydrazonoyl bromide and 1-[3,5-dimethyl-1-(4-nitrophenyl)-1H-pyrazol-4-yl]ethan-1-one as starting materials. The treatment of 1-[3,5-dimethyl-1-(4-nitrophenyl)-1H-pyrazol-4-yl]ethan-1-one with methyl hydrazinecarbodithioate or hydrazinecarbothioamide afforded 2-[1-[5-methyl-1-(4-nitrophenyl)-1H-pyrazol-4-yl]ethylidene]hydrazine derivatives. The targeted 1,3,4-thiadiazolyl derivatives were prepared by the reaction of 2-[1-[5-methyl-1-(4-nitrophenyl)-1H-pyrazol-4-yl]ethylidene]hydrazine derivatives with hydrazonoyl chloride derivatives. The reaction of N-(4-nitrophenyl)acetohydrazonoyl bromide with 2-[(methylthio)carbonthioyl]hydrazones in absolute ethanol in the presence of triethylamine afforded the corresponding 1,3,4-thiadiazole derivatives. The newly synthesized compounds were fully characterized by 1H NMR, 13C NMR, IR, MS, and elemental analysis. Moreover, the antimicrobial activity of the synthesized 1,3,4-thiadiazole derivatives were tested against E. coli, B. mycoides, and C. albicans. Four compounds outperformed the other produced compounds in terms of antimicrobial activity.

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Environmentally Benign and User-Friendly In Situ Generation of Nitrile Imines from Hydrazones for 1,3-Dipolar Cycloaddition

Nitrile imines are highly reactive and versatile dipoles and conventionally generated in situ from unstable hydrazonyl halides under basic conditions. Herein, we report the first green and user-friendly protocol for in situ generation of nitrile imines from Oxone-KBr oxidation of hydrazones and base-promoted dehydrobromination. The nitrile imines were demonstrated for 1,3-dipolar cycloaddition with various dipolarophiles, including alkene and alkyne groups. With its green nature, ease of operation, and air and moisture tolerance, we expect our method will find wide applications in organic synthesis.

Transition-Metal-Free Coupling of 1,3-Dipoles and Boronic Acids as a Sustainable Approach to C-C Bond Formation

The need for alternative, complementary approaches to enable C-C bond formation within organic chemistry is an on-going challenge in the area. Of particular relevance are transformations that proceed in the absence of transition-metal reagents. In the current study, we report a comprehensive investigation of the coupling of nitrile imines and aryl boronic acids as an approach towards sustainable C-C bond formation. In situ generation of the highly reactive 1,3-dipole facilitates a Petasis-Mannich-type coupling via a nucleophilic boronate complex. The introduction of hydrazonyl chlorides as a complementary nitrile imine source to the 2,5-tetrazoles previously reported by our laboratory further broadens the scope of the approach. Additionally, we exemplify for the first time the extension of this protocol into another 1,3-dipole, through the synthesis of aryl ketone oximes from aryl boronic acids and nitrile N-oxides.

Efficient Methods for the Synthesis of Novel Arylazothiazoles Based on Acetylferrocene or Adamantane

BACKGROUND

Hydrazonoyl halides are convenient for the synthesis of arylazothiazoles.

MATERIALS AND METHODS

A series of novel arylazothiazoles were efficiently synthesized from the reaction of hydrazonoyl chlorides with 2-(adamantan-2-ylidene)hydrazinecarbothioamide or 2-(ferrocenyl-1-ylidene)hydrazinecarbo-- thioamide in dioxane used as an aprotic solvent because of its lower toxicity and higher boiling point (101 °C) and triethylamine at reflux. The reaction mechanistic pathway proceeded by the nucleophilic substitution reaction by the elimination of hydrogen chloride to give thiohydrazonates as intermediate, which in situ undergo intramolecular cyclization and loss of water molecule to afford the final product of novel arylazothiazoles. This method is simple with good yield and excellent purities.

RESULTS AND DISCUSSION

The synthetic schemes for the final products are proposed and discussed. The chemical structures of the final products were identified by different techniques, such as elemental analysis, Fourier-transform infrared spectroscopy (FT-IR), nuclear magnetic resonance (NMR), and mass spectrometry (MS).

CONCLUSION

In this article, we prepared arylazothiazoles from the reaction of 2-(adamantan-2-ylidene)hydrazinecarbothioamide or 2-(ferrocenyl-1-ylidene)hydrazinecarbothioamide with hydrazonoyl halides.

Biological Activity, Apoptotic Induction and Cell Cycle Arrest of New Hydrazonoyl Halides Derivatives

BACKGROUND

The hydrazonoyl halides are presently an important target in the field of medicinal chemistry. The interest in the chemistry of hydrazonoyl halides is a consequence of the fact that they undergo a wide variety of reactions which provide routes to a myriad of both heterocyclic and acyclic compounds. In addition, they have diverse biological activities such as antiviral, anthelmintic, antiarthropodal, fungicidal, herbicidal, insecticidal, pesticidal, acaricidal and miticidal Activity correlated to the presence of hydrazonoyl halides. Moreover, many applications in both industrial and pharmaceutical fields have been found to be associated with these halides. Depending on the above facts and continuation to our work, we herein report on the evaluation of the anticancer activity of these two halides prepared according to the published work and trying to know their molecular mechanism that they proceed to stop proliferation and metastasis of tumor cells by molecular tools such as real time PCR using different apoptotic genes, and cell cycle assay.

OBJECTIVE

The goal of this present study is to bring attention to the biological activities of hydrazonoyl halides and the molecular pathway they follow to exert their role in apoptotic death of cancer cell.

METHODS

Synthesis of hydrazonoyl halides 2c and 2f. The cytotoxic effect against different human cancer cell lines PC3, HepG-2, HCT-116, MCF-7 and also on normal human cell lines as MCF-10 and MCF-12 in a monolayer culture model was evaluated. Their mechanism of action inside cancer cell was evaluated using different molecular tools.

CONCLUSION

Strong and promising chemotherapeutic hydrazonoyl halides (2a-2f) were evaluated for their different biological activities. As antimicrobial agents, results indicated that three compounds 2a, 2e and 2f exhibited high activity against two tested gram positive bacteria Staphylococcus aureus, Bacillus subtilis, and gram negative ones Escherichia coli, and Pseudomonas aeruginosa, the rest of the compounds were found to be moderately active against the tested microorganisms. Regarding their antifungal effect, compound 2c exhibited potent and promising effect against Candida albicans, while 2b was the most potent toward Aspergillus flavus Link. The compound 2f has repellent effect. With respect to the in vitro antitumor screening, this was done on different human cancer cell lines; namely PC3, HepG-2, HCT-116, MCF-7 and also on normal human cell lines; as MCF-10 and MCF-12 (normal breast epithelial cell and non-tumorigenic breast epithelial cell line) in a monolayer culture model where screening has been conducted at 100μg/ml (single dose test). Single dose test (100μg/ml) showed that, in case of PC3, all compounds have cytotoxic activity over 90% inhibition, 4 compounds have cytotoxic activity with 100% inhibition with Human colon cancer cell line, 4 compounds showed over 90% inhibition with MCF7 cell line and 4 compounds showed cytotoxic activity over 90% inhibition with HepG-2. Results of IC50 values for most promising compounds showed compounds with values lower than 20μM for all tested human cancer cell line. The promising hydrazonoyl halide 2c and 2f were selected for molecular study to know how they could act inside cancer cell causing death. Two biochemical tests were performed using the two halides 2c and 2f to predict their mechanism of action against breast carcinoma. Real time PCR analysis indicates that the two compounds induced the apoptosis of MCF7 cells through the up regulation of caspase-3, BAX mediated P53 mechanism but unfortunately, they promote the expression of anti-apoptotic protein BCL2. Also, cell cycle assay was performed using two different cell lines MCF7 and HCT116 and data revealed that the two compounds 2c and 2f induced apoptotic cells death of both lines via cell growth arrest at G2/M phase. In addition, it was noted that 2c induced arrest in the two lines more efficiently than 2f at G2/M phase.

A Facile Entry for Synthesis of 3-arylazo Derivatives of [1,2,4]Triazolo[4,3-a] Benzimidazole and [1,2,4]Triazolo[3,4-b]Quinazolin-5-one

A simple synthetic strategy is described for synthesis of hitherto unreported 3-arylazo derivatives of both [1,2,4]triazolo[4,3-a]benzimidazole and [1,2,4]triazolo[3,4-b]quinazolin-5-one 6 and 7, respectively. This strategy utilises reactions of 3-chloro-1,5-diarylformazans 1 with 2-mercaptobenzimidazole 2 and 2,3-dihydro-2-thioxoquina-zolin-4(1H)-one 4 or their 2-methylthio derivatives 3 and 5, respectively. A plausible reaction mechanism is suggested for the formation of the isolated products 6 and 7.

Synthesis and Tautomeric Structure of 2-arylazo-4H-imidazo[2,1-b][1,3,4]thiadiazines

Two series of the title compounds were prepared via reaction of N-aryl 2-oxohydrazonoyl halides with 1-amino-4-phenylimidazoline-2-thione. Their tautomeric structure was elucidated by spectral analysis, and the correlation of their acid dissociation constants with the Hammett equation, to be as the hydrazone form.

Synthesis, Cytotoxicity, Antimicrobial and Docking Simulation of Novel Pyrazolo[3,4-d]pyrimidine and pyrazolo[4,3-e][1,2,4]triazolo[3,4-c] pyrimidine Derivatives

BACKGROUND

Isobutyrohydrazonoyl bromide 1 was used as a precursor for the synthesis of 4-imino-3-isopropyl-1-(4-nitrophenyl)-1,4-dihydro-5H-pyrazolo[3,4-d]pyrimidin-5-amine 4, which was converted into hydrazino derivative 5 by heating with hydrazine hydrate at reflux. Hydrazino, as well as imino-amino derivatives, underwent condensation and cyclization reactions to give pyrazolo[ 3,4-d]pyrimidine and pyrazolo[4,3-e][1,2,4]triazolo[3,4-c]pyrimidine derivatives, respectively.

METHOD

Antimicrobial studies are performed using two-gram positive bacteria and two-gram negative bacteria.

RESULTS

Data revealed that compound 9a is the most promising antibacterial agent with high efficiency (low MIC value (48 μg/ml)). The cytotoxic assay was investigated for in vitro antitumor screening against Caucasian breast adenocarcinoma MCF7, hepatocellular carcinoma HepG2 and colon carcinoma HCT-116 cell lines.

CONCLUSION

The results are compared with doxorubicin standard anticancer drugs as well as normal cell lines like MCF10 and MCF12. Molecular docking was carried out for the highest potent compound 8c with the binding site of dihydrofolate reductase enzyme DHFR PDB:ID (1DLS).

A review on bis-hydrazonoyl halides: Recent advances in their synthesis and their diverse synthetic applications leading to bis-heterocycles of biological interest

This review covers a summary of the literature data published on the chemistry of bis-hydrazonoyl halides over the last four decades. The biological activities of some of the bis-heterocyclic compounds obtained from these bis-hydrazonoyl halides are also reviewed and discussed.

A new one-pot synthesis of novel hetarylazo-heterocyclic colorants and study of their solvatochromic properties

A simple synthetic strategy for synthesis of new series of hetarylazo-heterocycles is described. The effects of solvent on their electronic absorption spectra were analyzed using Kamlet–Taft equation. The results of fitting coefficients indicated that the solvatochromism of the studied compounds is mainly due to the solvent polarity rather than the solvent basicity and acidity.

Utility of N-aryl 2-aroylhydrazono-propanehydrazonoyl chlorides as precursors for synthesis of new functionalized 1,3,4-thiadiazoles with potential antimicrobial activity

Starting from N-aryl 2-aroylhydrazono-propanehydrazonoyl chlorides, a series of new functionalized 1,3,4-thiadiazoles were prepared. The structures of the compounds prepared were confirmed by both elemental and spectral analyses as well as by alternate synthesis. The mechanisms of the studied reactions are outlined. The antimicrobial activities of the compounds prepared were screened and the results showed that most of such compounds exhibit considerable activities.

Functionalized formazans: A review on recent progress in their pharmacological activities

This review provides an up to date information about the diverse pharmaceutical activities of formazans. The bibliography includes 97 references which have been published during the period from 1980 to 2013. The covered biological activities of the title compounds include antioxidant, anticonvulsant, therapeutic, anthelmintic, anti-tubercular, antiviral, anti-inflammatory, anticancer, anti-HIV, antimicrobial, antiparkinsonian, cardiovascular and antiproliferative activities.

1,3,4-Thiadiazoles of pharmacological interest: Recent trends in their synthesis via tandem 1,3-dipolar cycloaddition: Review

This review article presents a survey of the utility of a new synthetic strategy for 1,3,4-thiadiazole derivatives based on reactions of nitrilimines with various functionalized sulfur dipolarophiles which proceed via tandem in situ 1,3-dipolar cycloaddition and β-elimination of simple molecule from the initially formed cycloadduct. The biological activities of some of the compounds prepared by such a strategy are pointed out. Only the literature reports within the period from 2000 to mid 2012 are covered.

Synthesis and Tautomeric Structure of 3,7-bis(arylazo)-2,6-dimethyl-1H-imidazo[1,2-b]pyrazoles

Three series of 3,7-bis(arylazo)-2,6-dimethyl-1 H-imidazo[1,2- b]pyrazoles were prepared starting from N-aryl-2-oxo-propanehydrazonoyl chlorides. The acid dissociation constants p Ka were determined and correlated with the Hammett equation. The results of such correlations together with the spectroscopic data indicated that the title compounds exist predominantly in the 1 H-bis(arylazo) form.

Solvent and Substituent Effects on the Electronic Spectra of 3-Arylazo-Imidazo[1,2-b]pyrazolo[4,3-d]-pyridazines

A series of new 3-arylazo-6-methyl-2,8,9-triphenyl-8 H-imidazo[1,2- b]pyrazolo[4,3- d]pyridazines was prepared via reaction of hydrazonoyl halides with 3-hydrazonoacetyl-4-cyano-1,5-diphenylpyrazole. The structures of the compounds prepared were confirmed by spectral and elemental analyses. The solvatochromic and substituent effects on the absorption spectra of these azo dyes were interpreted by correlation of absorption frequencies with Kamlet–Taft and Hammett equations, respectively.

Synthesis and Tautomeric Structure of Novel 3-Arylazo-Imidazo[1,2-b]Pyrazolo[4,3-d]Pyridazines

Treatment of 3-acetyl-5-amino-4-cyano-1-phenylpyrazole with hydrazine hydrate afforded the hydrazone derivative. Reaction of the latter hydrazone with hydrazonoyl chlorides was found to be site selective as it afforded the corresponding formazan and not the amidrazone derivatives. The 1H NMR spectra of the formazan derivatives indicated that they exist as the bis-hydrazone tautomers. Acid-catalysed cyclisation of these dihydroformazans afforded the respective 9-amino-3-arylazo-6-methyl-8-phenyl-2-substituted-8 H-imidazo[1,2- b]pyrazolo[4,3- d]pyridazines whose electronic absorption spectra revealed that they exist predominantly in the arylazo tautomeric form. The structures of all compounds prepared were confirmed by spectral and elemental analyses. Also the mechanism of the reactions studied are discussed.

Hydrazonoyl Halides: Their Versatile Biological Activities

The various biological activities namely anthelmintic, antiarthropodal, antiviral, antimicrobial, herbicidal, antisarcoptic, acaricidal, insecticidal and miticidal activities exhibited by the hydrazonoyl halides are surveyed. Also, the uses of such halides as pesticides, weed controlling and antihypertensive agents as well as lipoxygenase and cyclo-oxygenase inhibitors are presented. Furthermore, their contact dermatitis and phytotoxicity effects are pointed out in addition to their metabolic fate.

Synthesis and Tautomeric Structure of 3,6-bis(arylazo)pyrazolo [1,5-a]pyrimidine-5,7(4H,6H)-diones

Two series of 3,6- bis(arylazo)pyrazolo[1,5- a]pyrimidine-5,7-diones were prepared, and their acid dissociation constant pKas were determined and correlated with the Hammett equation. The results of these correlations, together with the spectroscopic data, indicated that the title compounds exist predominantly in the 3-arylazo-6-arylhydrazonopyrazolo[1,5- a]pyrimidine-5,7-dione tautomeric form, both in the solid and solution phases.