5,6-Dihydro-[1,2,5]oxadiazolo[3,4-<i>d</i>]pyridazine-4,7-dione

Abstract

1,2,5-Chalcogenadiazoles fused with electron-withdrawing heterocycles have been actively investigated for the preparation of organic photovoltaic materials. [1,2,5]Oxadiazolo[3,4-d]pyridazines are much less studied than other chalcogenadiazolopyridazines due to their low availability. In this communication, we report our study showing that 5,6-dihydro-[1,2,5]oxadiazolo[3,4-d]pyridazine-4,7-dione, a key precursor for the synthesis of 4,7-dihalo-[1,2,5]oxadiazolo[3,4-d]pyridazines, is formed via the cyclization of 1,2,5-oxadiazole-3,4-dicarbohydrazide in hydrochloric acid. The structure of the newly synthesized compound was established by means of elemental analysis; high-resolution mass spectrometry; 1H and 13C NMR; IR spectroscopy, and mass spectrometry.

Keywords

• [1,2,5]oxadiazolo[3,4-d]pyridazines
• ring closure
• 5,6-dihydro-[1,2,5]oxadiazolo[3,4-<i>d</i>]pyridazine-4,7-dione