3-(5-Phenyl-2H-tetrazol-2-yl)pyridine

Ostrovskii V.А., Danagulyan G.G., Nesterova O.M., Pavlyukova Y.N., Tolstyakov V.V., Zarubina O.S., Slepukhin P.А., Esaulkova Y.L., Muryleva A.А., Zarubaev V.V., Trifonov R.E.

Nonannulated tetrazolylpyrimidines in the structure of which the heterocyclic fragments are separated by hydrazinocarbonylmethyl, methylpyrazolyl groups or a sulfur atom were synthesized. Some of these compounds showed moderate in vitro activity against H1N1 subtype of influenza A virus. The selectivity index of the anti-influenza action of {5-[(4,6-dimethylpyrimidin-2-yl)sulfanyl]-1H-tetrazol-1-yl}acetic acid, which has very low cytotoxicity, was twice as high as the selectivity index of the reference drug rimantadine.

Abedinifar F., Mahdavi M., Rezaei E.B., Asadi M., Larijani B.

Abstract: ''Chan-Evans-Lam'' (CEL) reaction is the copper-mediated cross-coupling of N-nucleophiles with boronic acids that was independently reported in 1998 by Chan, Evans, and Lam for the first time. This reaction is accom-plished at room temperature with a remarkably wide range of nucleophiles. In the recent decade, it has been particularly attractive as a convenient method for constructing the various C–N bonds in organic synthesis. Therefore, a compre-hensive survey through all reported process was crucial. In this review, we summarized research progress about N-Arylation, based on the type of N-nucleophile involved in this reaction and catalysts from 2012 onwards.

Chen J., Li J., Dong Z.

Bégué D., Dargelos A., Wentrup C.

Both photolysis and flash vacuum pyrolysis (FVP) of tetrazoles (1/5) are known to generate nitrile imines (13, 19, and 38), which rearrange to 1H-diazirines, imidoylnitrenes, and carbodiimides. Moreover, FVP of 5-aryltetrazoles is a convenient source of aryldiazo compounds (30/47) and arylcarbenes, including pyridylcarbenes. The factors that determine which path is followed are poorly understood. Calculations at the density functional theory and CASPT2 levels now examine cyclization of N-phenylnitrile imine 13 to indazole 17. A corresponding cyclization of C-phenylnitrile imine 19 can also lead to indazole, but this reaction, which passes through a carbenic nitrile imine, requires a much higher activation energy and is therefore not competitive with the known rearrangements to phenyldiazirines, ring expansion to diazenylcycloheptatetraene, or a new, potential rearrangement to cyanoazepine. C-(2-Pyridyl)nitrile imine 38 is predicted to undergo a new rearrangement to cyanopyridine N-imide 40 with an activation energy of 43 kcal/mol. The experimental observation that 2-pyridyldiazomethane 47 is actually formed requires a reaction with an energy barrier below 43 kcal/mol. This is found in the H-transfer from the tetrazole ring in 5-(2-pyridyl)tetrazole to the pyridine ring with a subsequent formation of 1H-2-(diazomethylene)pyridine and elimination of N2 with a barrier of ca. 26 kcal/mol. This new, facile mechanism has not previously been considered.

Popova E.A., Trifonov R.E., Ostrovskii V.A.

The tetrazole ring is an important pharmacophore. It is a structural component in many drugs, drug candidates (or lead compounds) and various biochemical reagents. This review summarizes data on the use of tetrazoles in biomedicine published in the last 10 – 15 years and also views on the nature of their biological effects. The prospects for the development of new biologically active substances containing a tetrazolyl pharmacophore are analyzed. The bibliography includes 263 references.

Motornov V., Latyshev G.V., Kotovshchikov Y.N., Lukashev N.V., Beletskaya I.P.

Vantourout J.C., Miras H.N., Isidro-Llobet A., Sproules S., Watson A.J.

We report an investigation of the Chan-Lam amination reaction. A combination of spectroscopy, computational modeling, and crystallography has identified the structures of key intermediates and allowed a complete mechanistic description to be presented, including off-cycle inhibitory processes, the source of amine and organoboron reactivity issues, and the origin of competing oxidation/protodeboronation side reactions. Identification of key mechanistic events has allowed the development of a simple solution to these issues: manipulating Cu(I) → Cu(II) oxidation and exploiting three synergistic roles of boric acid has allowed the development of a general catalytic Chan-Lam amination, overcoming long-standing and unsolved amine and organoboron limitations of this valuable transformation.

Siva Reddy A., Ranjith Reddy K., Nageswar Rao D., Jaladanki C.K., Bharatam P.V., Lam P.Y., Das P.

Copper(ii)-catalyzed boronic acid promoted chemoselective N-arylation of unprotected aminophenols has been developed. Selective N-arylation of 3-aminophenol is achieved with a Cu(OAc)2/AgOAc combination in MeOH at rt, whereas the chemoselective N-arylated products of 4-aminophenol can be obtained with a Cu(OAc)2/Cs2CO3 system and benzoic acid as an additive. These ligand-free conditions and "open-flask" chemistry are robust and compatible with a wide range of functional groups. The mechanistic investigation for this selective N-arylation has been studied by considering Density Functional Theory (DFT) calculations.

Mallia C.J., Burton P.M., Smith A.M., Walter G.C., Baxendale I.R.

A flow system to perform Chan–Lam coupling reactions of various amines and arylboronic acids has been realised employing molecular oxygen as an oxidant for the re-oxidation of the copper catalyst enabling a catalytic process. A tube-in-tube gas reactor has been used to simplify the delivery of the oxygen accelerating the optimisation phase and allowing easy access to elevated pressures. A small exemplification library of heteroaromatic products has been prepared and the process has been shown to be robust over extended reaction times.

Onaka T., Umemoto H., Miki Y., Nakamura A., Maegawa T.

A mild and regioselective 2-arylation of 5-substituted tetrazoles is described. The reaction proceeds regioselectively with a variety of arylboronic acids in the presence of [Cu(OH)(TMEDA)]2Cl2 to afford 2,5-disubstituted tetrazoles. This is the first report of highly regioselective arylation of 5-alkyltetrazoles.

Filimonov D.A., Lagunin A.A., Gloriozova T.A., Rudik A.V., Druzhilovskii D.S., Pogodin P.V., Poroikov V.V.

The freely accessible web resource PASS Online is presented. This resource is designed for the prediction of the biological activity spectra of organic compounds based on their structural formulas for more than 4000 types of biological activity with average accuracy above 95% ( http://www.way2drug.com/passonline ). The prediction is based on an analysis of the structure-activity relationships in the training set containing information on the structure and biological activity of more than 300000 organic compounds. The possibilities and limitations of this approach are described. Recommendations are given for interpreting the prediction results. Examples are given for the practical use of the PASS Online web resource in order to establish priorities for chemical synthesis and biological testing of substances on the basis of prediction results. The further trends are considered for the using PASS Online as an Internet platform for joint projects of academic researchers for the search and development of new pharmaceutical agents.

Liu C., Li Y., Ding J., Dong D., Han F.

The development of a highly efficient and practical protocol for the direct C-N coupling of H-tetrazole and boronic acid was presented. A careful and patient optimization of a variety of reaction parameters revealed that this conventionally challenge reaction could indeed proceed efficiently in a very simple system, that is, just by stirring the tetrazoles and boronic acids under oxygen in the presence of different Cu(I) or Cu(II) salts with only 5 mol % loading in DMSO at 100 °C. Most significantly, the reaction could proceed very smoothly in a regiospecific manner to afford the 2,5-disubstituted tetrazoles in high to excellent yields. A mechanistic study revealed that both tetrazole and DMSO are crucial for the generation of catalytically active copper species in the reaction process in addition to their role as reactant and solvent, respectively. It is demonstrated that in the reaction cycle, the Cu(I) catalyst could be oxidized to Cu(II) by oxygen to form a [CuT2D] complex (T = tetrazole anion; D = DMSO) through an oxidative copper amination reaction. The Cu(II) complex thus formed was confirmed to be the real catalytically active copper species. Namely, the Cu(II) complex disproportionates to aryl Cu(III) and Cu(I) in the presence of boronic acid. Facile elimination of the Cu(III) species delivers the C-N-coupled product. The results presented herein not only provide a reliable and efficient protocol for the synthesis of 2,5-disubstituted tetrazoles, but most importantly, the mechanistic results would have broad implications for the de novo design and development of new methods for Cu-catalyzed coupling reactions.

Wentrup C., Kvaskoff D.

Several aromatic and heteroaromatic nitrenes and carbenes undergo photochemical and sometimes also thermal ring opening. Depending on benz-annelation, the ring-opened species may have the character of either nitrenes (for α-annelation) or 1,5-(1,7-)-biradicals (for β-annelation). Both types have been observed, and they are clearly distinguished by their characteristic electron spin resonance spectra. In addition, ring opening of hetarylnitrenes to nitrile ylides can be observed whenever there is a meta-relationship between a ring nitrogen atom and the nitrene (or carbene) centre. The factors governing the two types of ring opening have been investigated. The nitrenes and carbenes are generated by either low temperature Ar matrix photolysis or flash vacuum thermolysis of azides, tetrazoles, triazoles, or diazo compounds with matrix isolation of the products.

Dolomanov O.V., Bourhis L.J., Gildea R.J., Howard J.A., Puschmann H.

New software,OLEX2, has been developed for the determination, visualization and analysis of molecular crystal structures. The software has a portable mouse-driven workflow-oriented and fully comprehensive graphical user interface for structure solution, refinement and report generation, as well as novel tools for structure analysis.OLEX2seamlessly links all aspects of the structure solution, refinement and publication process and presents them in a single workflow-driven package, with the ultimate goal of producing an application which will be useful to both chemists and crystallographers.

Trifonov R.E., Ostrovskii V.A.

Published data on protolytic equilibria involving tetrazole hetero ring are summarized. The information is systematized according to the types of protolytic equilibria.

Ostrovskii Vladimir A., Chernova Ekaterina N., Zhakovskaya Zoya A., Pavlyukova Yulia N., Ilyushin Mikhail A., Trifonov Rostislav E.

Rapid processes of tetrazole decomposition serve as sources of chemical energy stored in the five-membered ring, as well as gaseous products, primarily molecular nitrogen. Due to these properties, energetic tetrazole derivatives have found applications in various fields of science, engineering and technology, for example as components of energetic materials and products, as well as in emergency rescue equipment. The review presents an alternative view of the processes of tetrazoles decomposition, focusing on the diversity, differences, and similarities of the mechanisms and degradation products formed under the action of external energy sources. Some of these products are valuable reagents for the synthesis of previously inaccessible substances, as well as promising objects of analytical, medical, and bioorthogonal chemistry.The bibliography includes 140 references.