<p>A method for obtaining uncondensed bicyclic structures containing rings of 4,5-dihydronitrothiophene 1,1-dioxide and pyrazole is proposed. The synthesis scheme includes the stage of obtaining Michael adducts by 1,4-addition of acetylacetone to the diene system of nitrosulfodienes—2-benzylidene-4-nitro-2,5-dihydrothiophene 1,1-dioxide and its analogues, and the subsequent interaction of the adducts with hydrazine hydrate or ethylhydrazine to form target bicycles. We revealed the patterns of interaction of 3-[(aryl)(3-methyl-4-nitro-1,1-dioxido-4,5-dihydrothiophene-2-yl)methyl]pentane-2,4-diones with hydrazine hydrate and its derivatives, depending on the reagent structure and reaction conditions. The resulting products are characterized by physicochemical methods, including X-ray diffraction analysis.</p> Graphical abstract <p></p>