Keywords: 1-R-5-aminotetrazoles, N-arylcyanamides, 1-R-tetrazoles.C-and N-tetrazolyl groups enter into the composition of a series of biologically active compounds, many of which are used in medicinal practice [1,2]. This is linked primarily with the unique structure of the tetrazole ring which, depending on the location of substituents, may be a bioisostere of a carboxyl or an amide grouping, possessing several advantages over them [2,3]. One of the most preferred routes for making a 1-monosubstituted tetrazole ring is the heterocyclization of primary amines with triethyl orthoformate and sodium azide [3]. This process is used for the synthesis of tetrazoles, starting from primary amines of various nature, including aliphatic, aromatic, and heterocyclic [4][5][6][7][8][9]. It was shown that the reaction proceeds smoothly with the participation of only the simplest alkyl and aryl amines. It was discovered that 2,4-dinitroaniline does not react [7], and in the case of ortho-phenylenediamine the process stops at the stage of forming benzimidazole, the condensation product of triethyl orthoformate with the initial amine [6]. Under analogous conditions thiosemicarbazide forms a 2-aminothiadiazole [7]. Conversion products of several other compounds with a primary amino group, including hydrazine, phenylhydrazine, melamine, and aminoguanidine, failed to be identified [7]. The behavior of other functionally substituted primary amines has not been studied up to the present time, in spite of the obvious effect of the nature of the substituent on the course of the heterocyclization reaction.In the development of these investigations and with the aim of broadening the preparative possibilities of this reaction, the heterocyclization of some alkyl-, aryl-, and hetarylamines has been studied in this work. These include substances of a series of widely known pharmaceutical preparations possessing antibacterial and antiviral action, comprising sulfanilamide, sulfaethidole, sulfadimidine, rimantadine, etc. It was discovered that primary amines 1 react with sodium azide and triethyl orthoformate in acetic acid at a molar ratio of reactants of 1:1.1:3, forming the corresponding 1-monosubstituted tetrazoles 2.

Reactions of substituted 1,3-and 1,4-phenylenediamines with sodium azide and triethyl orthoformate in the presence of acetic acid led to the formation in high yields of the corresponding 1,12 -phenylenebis(1H-tetrazoles). The presence of electron-acceptor groups in the molecules of the initial diamines reduces the yield of the target heterocycles. With 2-nitro-1,4-phenylenediamine the prevailing product was 2-nitro-4-(1H-tetrazol-1-yl)aniline. The obtained bistetrazoles in basic environment suffer an opening of one or both heterocycles forming cyanamides.The growing interest to the synthesis of new functionally substituted tetrazole derivatives is due to the inherent to this class compounds biological activity, chemical and metabolic stability, high energy store and capability of complex formation [1-3].Bi-and polynuclear tetrazoles attract attention as chelating agents and initial compounds for building up one-, two-, and three-dimensional metal-containing supramolecular structures and developing materials with unusual magnetic properties, photo-and thermochromism ([3-5] and references cited there). Besides bicyclic tetrazoles are promising for the synthesis both of tetrazole-containing and other bifunctional and macroheterocyclic systems [6], and also of linear oligoheterocycles [7]. The application of 1,12 -(1,3-phenylene)bistetrazole was described as an effective ligand in the catalyzed by palladium salts cross-coupling of aryl halides and arylboric acids [8].Although a large amount of information exists on the opportunities of 1,3-and 1,4-phenylenebistetrazoles application, the development of approaches to their synthesis is scanty. An efficient procedure for preparation of 1-substituted tetrazoles by the heterocyclization of appropriate amines under the treatment with sodium azide and triethyl orthoformate in acetic acid was poorly studied with respect to the synthesis of phenylenebistetrazoles. In the preceding research [9, 10] concerning a limited range of substrates with equivalent or similar in the reactivity amino groups it was demonstrated that both amino groups of phenylenediamine underwent the heterocyclization disregarding the reaction conditions and the reagents ratio. The opening of the tetrazole ring under the action of bases practically important for the synthesis of N-arylcyanamides and 5-amino-1-aryltetrazoles [10-13] was not virtually investigated on the mentioned phenylenebistetrazoles: Only the behavior was described of two simplest compounds of this series lacking other substituents [10]. The published data are insufficient for evaluating the applicability of these reactions to the functionally-substituted phenylenediamines and phenylenebistetrazoles. In the present study we attempted to reveal the features of this processes depending on the presence and the type of substituents in the initial compounds.In the synthesis of phenylenebistetrazoles a series of appropriate 1,3-and 1,4-phenylenediamines was used containing substituents with donor and acceptor electronic effects (CH 3 , OCH 3 ...

Synthesis of New Functionally Substituted 1-R-Tetrazoles and Their 5-Amino Derivatives. -(VOITEKHOVICH, S. V.; VOROB'EV, A. N.; GAPONIK, P. N.; IVASHKEVICH, O. A.; Chem. Heterocycl. Compd. (N. Y.) 41 (2005) 8, 999-1004; Inst. Phys.-Chem. Probl., Belarus State Univ., Minsk 220080, Belarus; Eng.) -K. Woydowski 32-160

Features of the Synthesis of 1,1'-Phenylenebis(1H-tetrazoles) and Their Transformations in Basic Environment. -Reactions of phenylenediamines with sodium azide and triethyl orthoformate provides the title bis(tetrazoles), which suffer tetrazole opening under basic conditions. -(VOROB'EV, A. N.; BARANOVSKII, A. V.; GAPONIC, P. N.; IVASHKEVICH, O. A.; Russ.