Synthesis of fused tetrazole- and imidazole derivatives via iodocyclization

Synthesis of Tricyclic Tetrazoles by Cascade Diazotization/Intramolecular Radical C-H Heteroarylation of Arenes

A cascade diazotization/intramolecular radical C-H heteroarylation of 1-benzyloxy-5-aminotetrazoles and 1-phenethyl-5-aminotetrazoles as substrates using sodium nitrite and acetic acid without any heating, catalysis, irradiation, or electrolysis is reported. This one-pot reaction afforded the desired tricyclic tetrazole products in good yields (up to 94%) without isolation of the diazonium salt intermediate under mild reaction conditions.

Synthesis of 1,5-Disubstituted Tetrazoles in Aqueous Micelles at Room Temperature

The ongoing study is a Ugi-azide four-component reaction for the synthesis of 1,5-disubstituted tetrazole(1,5-DST), which involves an aldehyde, different amines, isocyanides, and as azide’s source the Trimethylsilylazide (TMSN3), in water as solvent using as catalyst the tetradecyltrimethylammonium bromide (TTAB) with a load of (10% mole), which provides a hydrophobic micellar reaction site. This approach is a step toward a green chemistry reaction of 1,5 disubstituted tetrazole. A serie of 1, 5- disubstituted tetrazole was synthesized by engaging a large substrate scope, leading to yields between 43% and 56%, which are compared afterwards with those obtained with methanol as solvent. The results were confirmed by HRMS, IR, and 1D NMR experiments.

Synthesis of 1-Substituted 1H-1,2,3,4-Tetrazoles Using Biosynthesized Ag/Sodium Borosilicate Nanocomposite

An expedient solvent-free methodology has been developed to produce 1-substituted 1H-1,2,3,4-tetrazoles using sodium borosilicate glass-supported silver nanoparticles (Ag NPs) as a novel heterogeneous catalyst. A cost-efficient, facile, and greener method was deployed for the creation of Ag/sodium borosilicate nanocomposite (ASBN) catalyst by using Aleurites moluccana leaf extract as a stabilizing and reducing agent. The ASBN catalyst was identified using the latest microscopic and spectroscopic techniques such as FT-IR, TEM, FESEM, XRD, EDS, and elemental mapping. The deployment of this new catalyst enables the preparation of assorted 1-substituted tetrazoles in good to high yields via an easy work-up procedure in a relatively short reaction time under environmentally friendly conditions without using harmful and toxic reducing agents. The ASBN catalyst can be recycled and reused multiple times without meaningful loss of activity. To extend the application of the ASBN, the performance of the quantitative structure-activity relationships model was investigated for protein binding and toxicity hazard considerations.

Tetrazoles via Multicomponent Reactions

Tetrazole derivatives are a prime class of heterocycles, very important to medicinal chemistry and drug design due to not only their bioisosterism to carboxylic acid and amide moieties but also to their metabolic stability and other beneficial physicochemical properties. Although more than 20 FDA-approved drugs contain 1 H- or 2 H-tetrazole substituents, their exact binding mode, structural biology, 3D conformations, and in general their chemical behavior is not fully understood. Importantly, multicomponent reaction (MCR) chemistry offers convergent access to multiple tetrazole scaffolds providing the three important elements of novelty, diversity, and complexity, yet MCR pathways to tetrazoles are far from completely explored. Here, we review the use of multicomponent reactions for the preparation of substituted tetrazole derivatives. We highlight specific applications and general trends holding therein and discuss synthetic approaches and their value by analyzing scope and limitations, and also enlighten their receptor binding mode. Finally, we estimated the prospects of further research in this field.

Application of a functionalized mesoporous silica catalyst to the synthesis of tetrazoles

Highly ordered MCM-41 was synthesized and functionalized with benzylic groups. The solid catalyst was used in the synthesis of aryl tetrazoles.

A review of syntheses of 1,5-disubstituted tetrazole derivatives

This report provides a brief overview of the various representative literature procedures for the synthesis of 1,5-disubstituted tetrazoles (1,5-DSTs) and fused 1,5-disubstituted tetrazoles with more than 120 references. Most of the published methods for the synthesis of 1,5-DSTs include the use of nitriles, amides, thioamides, imidoyl chlorides, heterocumulenes, isocyanates, isothiocyanates, carbodiimides, ketenimines, ketones, amines, and alkenes as the starting materials. The transformation of 1- and 5-substituted tetrazoles into 1,5-DSTs is also covered in this report.

A periodic density functional theory study of tetrazole adsorption on anatase surfaces: potential application of tetrazole rings in dye-sensitized solar cells

A density functional theory (DFT) method (periodic DMol(3)) with full geometry optimization was used to study the adsorption of tautomeric forms of tetrazole on anatase TiO2 (101), (100), and (001) surfaces. It was found that the adsorption of tetrazole on the TiO2 surfaces does not proceed via a dissociative process, and negative shifts in the Fermi level of TiO2 were noted upon N-containing heterocycle adsorption. The configuration of the tetrazole during adsorption and the corresponding adsorption energies on different surfaces and sites were estimated. In addition, it was found that tetrazole may be adsorbed on TiO2 surfaces through an interaction between a cation on the surface and a lone pair on the N1 or N2 atom of the tetrazole molecule. The results indicate that the adsorption of tetrazole through the N2 position (leading to the 1H tautomer) on an anatase TiO2 surface is favored over adsorption through the N1 position. In addition, it was observed that the photocatalytic activity of tetrazole-doped TiO2 is higher than that of a pure anatase TiO2 surface.

An Efficient One-Pot Three-Component Synthesis of Novel Sulfanyl Tetrazoles Using Ionic Liquids

An efficient, simple, and environmentally benign method for the synthesis of novel sulfanyl tetrazoles has been achieved by one-pot three-component reaction of phenacyl bromides/3-(2-bromoacetyl)coumarins with KSCN and NaN3using [Bmim]BF4ionic liquid. It could be reused and recycled for four runs without significant loss of product yield.

Synthesis and characterization of a novel high luminescent gold-2-mercapto-1-methyl-imidazole complex

Synthesis and characterization of a new gold-2-mercapto-1-methyl imidazole are reported. This new organic material shows an extraordinary fluorescence activity (superfluorescence) up to 220°C with an unusual quantum yield of 0.2. Both fluorescence and NMR spectroscopy were applied to understand the behavior of the gold-2-mercapto-1-methylimidazole complex. Results suggest that the superfluorescence activity can be attributed to the shrinking of the HOMO-LUMO band gap energy following complexation of the organic imidazole system with gold.

Ferric Hydrogensulfate [Fe(HSO4)3] As a Reusable Heterogeneous Catalyst for the Synthesis of 5-Substituted-1H-Tetrazoles and Amides

Ferric hydrogensulfate catalyzed the synthesis of 5-substituted 1H-tetrazoles via [2 + 3] cycloaddition of nitriles and sodium azide. This method has the advantages of high yields, simple methodology, and easy workup. The catalyst can be recovered by simple filtration and reused delivering good yields. Also, ferric hydrogensulfate catalyzed the hydrolysis of nitriles to primary amides under aqueous conditions. Various aliphatic and aromatic nitriles converted to the corresponding amides in good yields without any contamination with carboxylic acids.

Tandem regioselective synthesis of tetrazoles and related heterocycles using iodine

A one-pot, tandem process has been developed for the synthesis of a library of tetrazoles from aryl isothiocyanates. Condensation of aryl isothiocyanates with ammonia, and aryl amines (R-NH(2)) provided mono, 1,3-disubstituted symmetrical and unsymmetrical thioureas, which on desulfurization with molecular iodine (I(2)) led to formation of the corresponding heterocumulene (cyanamides or carbodiimides). The in situ generated heterocumulene on subsequent treatment with sodium azide at room temperature gave corresponding tetrazoles. The product regioselectivity for unsymmetrical 1,3-disubstituted thioureas was found to be correlated with the basicities (pK(a)'s) of the parent amines attached to the thiourea. Aryl-sec-alkyl unsymmetrical thioureas gave thioamido guanidino products rather than the 5-aminotetrazoles produced by HgCl(2) mediation of the reaction. Bis-thioureas derived from aryl isothiocyanates and hydrazine gave thiadiazoles exclusively.