The data obtained by the authors in the field of chemistry of 1,3,5-cycloheptatrienes and 1,3,5,7-cyclooctatetraenes with the participation of complexes of transition metals are summarized. The reactions of cyclocodimerization of 1,3,5-cycloheptatrienes and 1,3,5,7-cyclooctatetraenes with alkenes, dienes and alkynes in the presence of transition metal complexes, carried out by the type of [6π + 2π] - and [4π + 2π] -cycloaddition, are considered. Special attention is paid to the application of these reactions in the synthesis of practically important bi-, tri- and polycyclic strained compounds, as well as in the development of stereoselective methods for the synthesis of natural compounds.