Oxadiazole

Oxadiazoles are a class of heterocyclic aromatic^[1] chemical compounds of the azole family with the molecular formula C₂H₂N₂O. There are four isomers of oxadiazole:

• 
  1,2,3-oxadiazole
• 
  1,2,4-oxadiazole
• 
  1,2,5-oxadiazole
  (furazan)
• 
  1,3,4-oxadiazole

1,2,4-Oxadiazole, 1,2,5-oxadiazole, and 1,3,4-oxadiazole are all known and appear in a variety of pharmaceutical drugs including raltegravir, butalamine, fasiplon, oxolamine, and pleconaril. The 1,2,3-isomer is unstable and ring-opens to form the diazoketone tautomer;^[2] however, it does exist within the unusual sydnone motif.^[1]

In 2018, a compound called bis(1,2,4-oxadiazole)bis(methylene) dinitrate which might have 1.5 times the power of TNT was developed at the United States Army Research Laboratory (ARL) working with the Los Alamos National Laboratory.^[3]