This dissertation is focused on the development of new variants of 1,3-dipolar cycloaddition reactions. It also explores a combination of 1,3-dipolar cycloaddition in tandem with other chemical transformations in order to obtain new azoles and their condensed derivatives with useful properties, and study of the properties of the obtained compounds. The main focus of the work is on the development of new directions for the use of organic azides as effective 1,3-dipoles in [3+2]cycloaddition reactions, synthesis of 1,2,3-triazoles and their condensed derivatives, as well as studying the behaviour of alternative azides 1,3-dipoles in such transformations. 3-(Methylsulfonyl)prop-1-yne and 2-(prop-2-yn-1-yloxy)-6H-benzo[c]chromen-6-one were investigated for the first time in the CuAAC reaction. The peculiarities of the interaction of di(prop-2-yn-1-yl)amine with aryl azides have been elucidated and new bis-triazoles were synthesized. Previously undescribed conjugates of 1,2,3-triazole and 6H-benzo[c]chromen-6-one were obtained and their anticancer activity was investigated. The haloarylation products of acrylates by the Meerwein reaction, which were obtained from commercially available starting compounds, are convenient reagents for the synthesis of 2-azido-3-arylpropanoic acids. Methods for the preparation of 2-(1H-1,2,3-triazol-1-yl)-3-arylpropanoic acids and their derivatives as well as 4,5,6,7-tetrahydro-[1,2,3]triazolo[1,5-a]pyrazines were developed on the basis of 2-azido-3-arylpropanoic acids. A new approach to the synthesis of substituted [1,2,3]triazolo[1,5-a]pyrazines by combining a four-component Ugi reaction and non-catalytic Huisgen cyclization was proposed, which allows to obtain high-yield target products without the use of catalysts. A new example of the click reaction of hydrazonyl halides with active methylene nitriles is described. It was found that nitrileimines are highly reactive reagents in the interaction with active methylene nitriles, and can be used in the synthesis as alternatives to 1,3-dipole azides, for isostere substitutions of 1,2,3-triazole ring by 1H-pyrazole, which expands the synthetic capabilities of the developed methods, in particular, for screening for the biological activity of the obtained compounds. The 4-(1,2,4-oxazol-5-yl)-5-amino-1H-pyrazoles and 4-(1,2,4-oxazol-5-yl)-5-amino-1H-1,2,3-triazoles, which were not described previously, were obtained. It is shown that the interaction of 3-(1H-pyrrol-2-yl)/(1H-indol-3-yl)-3-oxopropanonitrile with nitrileimines occurs regioselectively with the formation of 5-aminopyrazoles. A domino reaction has been developed in which 2-aminothiophene-3-carboxylates or (2-(1-chloro-2-ethoxy-2-oxoethylidene)hydrazineyl)thiophene-3-carboxylates react with 2-(3-aryl-1,2,4-oxadiazol-5-yl)acetonitriles with the formation of thieno[3,2-e][1,2,3]triazolo[1,5-a]pyrimidin-5(4H)-ones and pyrazolo[1,5-a]thieno[3,2-e]pyrimidines.
