3-(1H-tetrazol-5-yl)-4(3H)-quinazolinone sodium salt (MDL 427): a new antiallergic agent

Three-Component Synthesis of 1-Substituted 5-Aminotetrazoles Promoted by Bismuth Nitrate

A nontoxic bismuth-promoted multicomponent synthesis of 5-aminotetrazoles and bistetrazoles is reported. The reaction of phenyl isothiocyanate, NaN3, and amine (primary aliphatic, aromatic, and aliphatic diamine) promoted by Bi(NO3)3·5H2O under microwave heating affords good yields, short reaction times, simple workup, and purification without column chromatography. A set of diagnostic 1H NMR signals was identified as a guide for quickly elucidating the exclusive (or main) regioisomer formed, with the stronger electron donor group located at heterocyclic nitrogen 1. This regioselectivity is strongly dependent on the electronic density of the amine. It is opposite to that obtained by several thiourea desulfurization methods promoted by thiophilic metals and metal-free protocols.

Visible Light Mediated Co-Catalyzed Isocyanide Insertion with Sulfonyl Azide: Synthesis of Sulfonyl Carbamimidic Azide and Sulfonyl Aminotetrazole via Carbodiimide Intermediate

Herein, we report an operationally simple and efficient protocol to prepare sulfonyl carbamimidic azide and N-sulfonyl aminotetrazole via Co-catalyzed three component coupling of sulfonyl azide (acts as nitrene source), isocyanide, and TMS-azide at room temperature under visible light. Initially, the carbamimidic azide is formed, which cyclizes only in the presence of base to deliver N-sulfonyl aminotetrazole in very good yields. The sulfonyl aminotetrazole can also be synthesized directly without isolating the carbamimidic azide in the presence of base. The sulfonyl azide is anticipated to generate nitrene and reacts with isocyanide to produce carbodiimide. Subsequent addition of azide (TMS-N3 ) to carbodiimide results in the formation of carbamimidic azide.

Pyrazole-Based Thrombin Inhibitors with a Serine-Trapping Mechanism of Action: Synthesis and Biological Activity

New antithrombotic drugs are needed to combat thrombosis, a dangerous pathology that causes myocardial infarction and ischemic stroke. In this respect, thrombin (FIIa) represents an important drug target. We herein report the synthesis and biological activity of a series of 1H-pyrazol-5-amine-based thrombin inhibitors with a serine-trapping mechanism of action. Among synthesized compounds, flexible acylated 1H-pyrazol-5-amines 24e, 34a, and 34b were identified as potent 16-80 nM thrombin inhibitors, which showed practically no off-targeting effect against other physiologically relevant serine proteases. To prove that synthesized compounds are covalent thrombin inhibitors, the most potent derivative 24e (FIIa IC₅₀ = 16 nM) was studied in a mass-shift assay, where it has been shown that 24e transfers its acyl moiety (pivaloyl) to the catalytic Ser195 of thrombin. Performed herein docking studies also confirmed the covalent mechanism of thrombin inhibition by synthesized compounds. Acylated aminopyrazoles found during this study showed only limited effects on plasma coagulation in activated partial thrombin time (aPTT) and prothrombin time (PT) in vitro assays. However, such thrombin inhibitors are expected to have virtually no effect on bleeding time and can be used as a starting point for developing a safer alternative to traditional non-covalent anticoagulants.

tert-Butyl Hydroperoxide Promoted the Reaction of Quinazoline-3-oxides with Primary Amines Affording Quinazolin-4(3H)-ones

An efficient and facile approach for the synthesis of quinazolin-4(3H)-ones via the reaction of quinazoline-3-oxides with primary amines is described. This approach is demonstrated to be applicable for a broad range of substrates and proceeds efficiently under metal-free and mild reaction conditions employing easily available tert-butyl hydroperoxide as the oxidant. Remarkably, 3-(2-(1H-indol-3-yl) ethyl)quinazolin-4(3H)-one 3w, which was conveniently obtained by this process in 70% yield, was an excellent precursor for the synthesis of bioactive evodiamine and rutaempine.

A Novel and Efficient Nano Alumina Based Cu (II) Catalyst for Three- Component Synthesis of 5-Substituted-1H-Tetrazoles

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Tetrazoles as one of the most important synthetic heterocyclic compounds have so many applications in organic chemistry, the photographic industry, coordination chemistry, explosives and in particular, medicinal chemistry. Numerous methods have been reported in the literature for synthesis of tetrazoles, but much of them have some drawbacks including the use of strong Lewis acids or expensive and toxic metals and employment of acidic media. Azides may react with acids to yield toxic and flammable HN3 gas. Furthermore, many methods used high polar solvents such as DMF at high temperatures and very tedious work-up. Heterogeneous catalysts are preferred because of owing to easy handling, safety, recoverability and reusability. Catalyst separation and recycling is highly desirable because catalysts are often very expensive. On the other hand, in spite of higher reactivity and selectivity of homogeneous catalysts, the difficulty of separating them from the reaction medium can lead to the problem of reusing the catalyst. Also, most homogeneous catalysts are thermally unstable. To benefit advantages of both types of catalysts, one solution is using nanoparticles. Their higher surface area is the advantages of nanoparticles, which allows them to enhance the reaction rate. Many commercially important catalysts include active nanoparticles spread on high area oxide supports. Such catalysts are highly complex materials that are optimized to work for plenty of turnovers at high reaction rates and with high selectivity. Aldehyde (1 mmol), hydroxylamine hydrochloride (0.10 mg, 1.5 mmol), sodium azide (0.10 g, 1.5 mmol), distilled water (5 mL) and nano Al2O3@PCH-Cu (II) (0.01g, 1.04% mol) were added to round bottom flask (25 mL) and stirred at room temperature. After the completion of the reaction, water (10 mL) was added into reaction mixture and filtered. Excess sodium azide and hydroxylamine hydrochloride are dissolved in water and the catalyst remains on the filter. Extraction of product with diethyl ether (3×10 mL) and then evaporation of ether afforded the product. The product was recrystallized using hot ethanol to obtain pure product. We synthesized a novel, stable, highly reactive and efficient nano-sized heterogeneous catalyst (nano Al2O3@PCH-Cu (II)). We characterized it by FT-IR, ICP, SEM, TGA and EDX analysis. This catalyst was used for the efficient one-pot three-component synthesis of 5-substituted-1H-tetrazoles. An one-pot three-component synthesis of 5-substituted-1Htetrazoles is conducted, a reaction between various benzaldehydes, hydroxyl amine hydrochloride and sodium azide in the presence of a novel and highly efficient nano alumina supported poly(carboxylic acid hydrazide) Cu(II) complex, nano Al2O3@PCH-Cu(II), as heterogeneous catalyst in H2O at room temperature. This method has very mild reaction conditions as well as the advantages of easy separation and reusability of the catalyst, very short reaction times, high yields and using H2O as green solvent. Furthermore, using this method very high TON and TOF values obtained for all isolated products.

DMSO as a Dual Carbon Synthon in One-pot Tandem Synthesis of N-alkylated Quinazolinones from Anthranilamides and Acetophenones

A new, efficient, metal-free, and DMSO intervened approach for the synthesis of N-alkylated quinazolinones from readily available 2-aminobenzamide and aryl methyl ketones in the presence of an oxidizing agent has...

Magnetic chitosan-copper nanocomposite: A plant assembled catalyst for the synthesis of amino- and N-sulfonyl tetrazoles in eco-friendly media

A greener, cost efficient and simple method is described to prepare copper nanoparticles (NPs) immobilized on the magnetic chitosan (one of the more versatile polysaccharides) using Euphorbia falcata leaf extract as reducing/stabilizing agent. The prepared catalyst (Cu NPs@Fe₃O₄-chitosan) was authenticated by field emission scanning electron microscope (FESEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), Scanning transmission electron microscopy (STEM), energy-dispersive X-ray spectroscopy (EDS), thermogravimetry/derivative thermogravimetry (TG/DTG), Vibrating sample magnetometer (VSM), and elemental mapping. TEM analysis indicates that Cu NPs with average sizes in 5-10 nm range is formed on magnetic chitosan with the spherical morphology. The Cu NPs@Fe₃O₄-chitosan was employed as a new catalyst for the synthesis of different tetrazoles by the reaction of various secondary or tertiary cyanamides with sodium azide in water under reflux conditions. Easy separation by external magnetic field, mild reaction conditions, low cost and the reusability are some of the beneficial features of this catalyst.

Synthesis, Antiproliferative, and Antioxidant Evaluation of 2-Pentylquinazolin-4(3H)-one(thione) Derivatives with DFT Study

The current study was chiefly designed to examine the antiproliferative and antioxidant activities of some novel quinazolinone(thione) derivatives 6–14. The present work focused on two main points; firstly, comparing between quinazolinone and quinazolinthione derivatives. Whereas, antiproliferative (against two cell lines namely, HepG2 and MCF-7) and antioxidant (by two methods; ABTS and DPPH) activities of the investigated compounds, the best quinazolinthione derivatives were 6 and 14, which exhibited excellent potencies comparable to quinazolinone derivatives 5 and 9, respectively. Secondly, we compared the activity of four series of Schiff bases which included the quinazolinone moiety (11a–d). In addition, the antiproliferative and antioxidant activities of the compounds with various aryl aldehyde hydrazone derivatives (11a–d) analogs were studied. The compounds exhibited potency that increased with increasing electron donating group in p-position (OH > OMe > Cl) due to extended conjugated systems. Noteworthy, most of antiproliferative and antioxidant activities results for the tested compounds are consistent with the DFT calculations.

Construction of 5-Aminotetrazoles via in Situ Generation of Carbodiimidium Ions from Ketones Promoted by TMSN3/TfOH

A novel synthetic approach for the synthesis of 5-aminotetrazoles has been developed by employing simple ketones as substrates. This methodology involved the N₂-extrusion/aryl migration of azido complexes as the key step for the in situ generation of carbodiimidium ion, which could further react with hydrazoic acid and cyclize intramolecularly to provide 5-aminotetrazoles in good to excellent yields. In addition, the regioselectivity of the reaction was studied and rationalized by density functional theory calculations.

A silver(i)-catalyzed cascade bicyclization strategy for synthesis of 5H-benzo[d]tetrazolo[5,1-b][1,3]thiazines

A simple and efficient protocol for silver(i)-catalyzed tandem reaction of o-alkynylphenyl isothiocyanates with sodium azide has been developed, affording a series of 5H-benzo[d]tetrazolo[5,1-b][1,3]thiazines in moderate to good yields. In this transformation, a [3 + 2] cycloaddition reaction mechanism was involved and two new rings were formed in one pot.

Palladium catalyzed carbonylative annulation of the C(sp2)-H bond of N,1-diaryl-1H-tetrazol-5-amines and N,4-diaryl-4H-triazol-3-amines to quinazolinones

Pd(ii) catalyzed direct C-H carbonylative annulation of N,1-diaryl-1H-tetrazol-5-amines and N,4-diaryl-4H-1,2,4-triazol-3-amines gave the corresponding triazole and tetrazole fused quinazolinones in good yields. This methodology offers a convenient method for the synthesis of these important heterocyclic scaffolds in a highly atom economical process. On the mechanistic aspect weakly nucleophilic triazole and tetrazole moieties function as both directing as well as intramolecular nucleophiles. The catalytically active C-H activated intermediate dimeric Pd complex was isolated and characterized which on exposure to CO gas gave the corresponding tetrazole fused quinazolinone derivative. On the basis of isolation of the intermediate and observed kinetic isotope effects, a mechanism has been proposed for the C-H activated direct carbonylative annulation reaction.

Bismuth-Catalyzed Synthesis of 2-Substituted Quinazolinones

The bismuth-catalyzed oxidative condensation of aldehydes with 2-aminobenzamide under aerobic conditions is reported using ethanol as the solvent. Good to excellent isolated yields (68-95%) of the corresponding 2-substituted quinazolinones were obtained under mild reaction conditions with excellent functional group tolerance. The quinazolinones were further functionalized to afford N-allylated quinazolinones, 2-aminopyridine derivatives, and annulated polyheterocyclic compounds via transition-metal catalyzed reactions.

Facile Synthesis of 1-(4-Bromophenyl)-1H-Tetrazol-5-Amine and Related Amide Derivatives

An efficient one-pot synthesis of 1-(4-bromophenyl)-1 H-tetrazol-5-amine was performed using 4-bromoaniline as the starting material. A novel and widely applicable amidation procedure was then employed, whereby 1-(4-bromophenyl)-1 H-tetrazol-5-amine was acylated with different acyl chlorides in the presence of lithium bis(trimethylsilyl)amide as catalyst, for the high-yield synthesis of [1-(4-bromophenyl)-1 H-tetrazol-5-yl]amide derivatives.

Convenient synthesis of 2,3-disubstituted quinazolin-4(3H)-ones and 2-styryl-3-substituted quinazolin-4(3H)-ones: applications towards the synthesis of drugs

Simple, convenient, and green synthetic protocols have been developed for the one pot synthesis of 2,3-disubstituted quinazolin-4(3H)-ones and 2-styryl-3-substituted quinazolin-4(3H)-ones under catalyst and solvent free conditions.

Synthesis and bioevaluation of novel 4-aminoquinoline-tetrazole derivatives as potent antimalarial agents

A series of novel tetrazole derivatives of 4-aminoquinoline were synthesized and screened for their antimalarial activities against both chloroquine-senstive (3D7) and chloroquine-resistant (K1) strains of Plasmodium falciparum as well as for cytotoxicity against VERO cell lines. Most of the synthesized compounds exhibited potent antimalarial activity as compared to chloroquine against K1-strain. Compounds with significant in vitro antimalarial activity were then evaluated for their in vivo efficacy in Swiss mice against Plasmodium yoelii following both intraperitoneal (ip) and oral administration, wherein compounds 20 and 23 each showed in vivo suppression of 99.99% parasitaemia on day 4.

ZnCl2/AlCl3/Silica (ZAS) as an Effective Heterogeneous Catalyst for the Synthesis of 5-Ryloxytetrazoles

A simple and efficient method for preparation of 5-aryloxy tetrazoles (3a-h) from arylcyanates (1a-h) with using ZnCl2/AlCl3/silica (ZAS) as an effective heterogeneous catalyst in solvent free are described with excellent yields and high purity. The rate of product formation was enhanced by introduction of electron donating substituents. The 1H NMR and chemical shifts and multiplicities are also discussed.

Synthesis, tautomeric structure and antimicrobial activity of 3-arylhydrazono-4-phenyl-[1,2,4]-triazepino[2,3-a]quinazoline-2,7(1H)-diones

A simple strategy for the synthesis of the hitherto unreported 3-arylazo-4-phenyl-[1,2,4]triazepino[2,3-H]quinazoline-2,7(1H)-diones is described. Spectral data indicated that the studied compounds exist predominantly in the hydrazone tautomeric form. The antimicrobial activity of the newly synthesized compounds was also evaluated. The results indicated that some of these compounds have moderate activity towards bacteria.