Synthesis, Intramolecular Cyclization, and Analgesic Activity of Substituted 2-[2-(Furancarbonyl)hydrazinylydene]-4-oxobutanoic Acids

Abstract— A method was proposed for the synthesis of substituted 2-[2-(furan-2-carbonyl)hydrazinylidene]-4-oxobutanoic acids by the reaction of 4-aryl-2,4-dioxobut-2-enoic acids with furan-2-carbohydrazide. It was found that substituted 2-[2-(furan-2-carbonyl)hydrazinylidene]-4-oxobutanoic acids undergo intramolecular cyclization in the presence of propionic anhydride to form the corresponding substituted 2-[2-(furan-2-carbonyl)hydrazinylidene]-4-oxobutanoic acids. The analgesic activity and acute toxicity of the obtained compounds were studied, it was found that the obtained compounds have a pronounced analgesic activity and low toxicity. According to the toxicity classification of drugs, the resulting substituted 2-[2-(furan-2-carbonyl)hydrazinylidene]-4-oxobutanoic acids and 2-[5-aryl-2-oxofuran-3(2H)-ylidene]furan-2-carbohydrazides belong to class V practically non-toxic drugs.