Synthesis of 5-(1,2,3-thiadiazol-4-yl)2-methylfuran-3-carboxamides

Acetylation of 2-methylfuran-3-carboxamides with acetic anhydride in the presence of magnesium perchlorate yields the corresponding 5-acetyl derivatives; their carboethoxyhydrazones have been synthesized via the reaction with carboethoxyhydrazine. The carboethoxyhydrazones undergo cyclization into the 5-(1,2,3-thiadiazol-4-yl)-2-methylfuran-carboxamides upon treatment with thionyl chloride under conditions of the Hurd–Mori reaction. In the case of (2-methyl-3-furoyl)proline esters, the optical activity is retained after the described transformations.