Synthesis and Biological Activity of 5-alkoxy- and 5-amino-substituted 3-bromo-4-nitro-1-(thietan-3-yl)-1H-pyrazoles

5-Alkoxy- and 5-amino-substituted 3-bromo-4-nitro-1-(thietan-3-yl)-1 H -pyrazoles were synthesized by reactions of 3,5-dibromo-4-nitro-1-(thietan-3-yl)-1 H -pyrazole with sodium alcoholates and primary amines. The structures of the synthesized compounds were established by IR, PMR, and 13 C NMR spectroscopy. In vitro studies of the antiplatelet, anticoagulant, and antioxidant activity revealed promising compounds, including 3-bromo-5-methoxy-4-nitro-1-(thietan-3-yl)-1 H -pyrazole with antioxidant action and 2-{[3-bromo-4-nitro-1-(thietan-3-yl)-1 H -pyrazol-5-yl]amino}ethan-1-ol with an antiplatelet effect. Results of in silico calculations predicted the absence of toxic risks (mutagenicity, oncogenicity, reproductive toxicity, local irritation) and acceptable bioavailability (in terms of the topological polar surface area).