1,2,5-Oxadiazoles

1,2,5-Oxadiazoles (furazans) and 1,2,5-oxadiazole 2-oxides (furoxans) as well as their benzannulated derivatives (benzo[c][1,2,5]oxadiazoles and benzo[c][1,2,5]oxadiazole 1-oxides) are a widely known subclass of heterocycles. 1,2,5-Oxadiazoles exhibit a unique set of properties that has led to their use in the design of pharmacologically active and high-energy compounds. Moreover, furazans and furoxans are used as valuable precursors for the synthesis of a number of structurally diverse nitrogen heterocycles. This article is a summary of new developments in the synthesis, reactivity, and applications of monocyclic and benzo-fused 1,2,5-oxadiazoles that appeared from 2007 to 2018.