Synthesis of Derivatives (3-Oxobut-1-en-1-yl), [2-(1,2,3-Thiadiazol-4-yl)ethen-1-yl], and [2-(1,2,3-Selenodiazol-4-yl)ethen-1-yl]-5-tert-butylfurancarboxylic Acids

Based on the known 3- and 2-acetoxymethyl derivatives of 5-tert-butylfuran-2- and 3-carboxylates the corresponding aldoesters were synthesized. By reacting with acetylmethylenetriphenylphosphorane under the conditions of the Wittig reaction, they were converted into 3- and 2-(3-oxobut-1-en-1-yl)-5-tert-butylfuran-2- and -3-carboxylates. Carbethoxyhydrazones of these compounds form the corresponding 1,2,3-thiadiazoles under the conditions of the Hurd-Mori reaction, and semicarbazones, when oxidized with selenium dioxide, form analogous 1,2,3-selenodiazoles. Alkaline hydrolysis of 3- and 2-(3-oxobut-1-en-1-yl)-5- and 3- and 2-[2-(1,2,3-thiadiazol-4-yl)ethen-1-yl]-5-tert-butylfuran-2- and -3-carboxylates leads to stable unsaturated acids, from which the corresponding acid chlorides were synthesized by treating with thionyl chloride. Selenodiazole derivatives, under the conditions of alkaline hydrolysis at room temperature, decompose to low molecular weight products with the release of colloidal selenium. Under the conditions of acid hydrolysis at room temperature, decomposition proceeds with the release of dihydrogen selenide.