A high-efficiency strategy for the synthesis of furoxans and 1,2,4-oxadiazoles has been developed, using tert-butyl nitrite (TBN) as the nitrogen source. Azaarene nitrile oxides as activated intermediates were generated in situ via methyl azaarene functionalization. When the reaction used TBN as the NO source under mild conditions, the corresponding furoxans were obtained in high yields (up to 92%). Unexpectedly, 1,2,4-oxadiazole bearing two quinoline groups was obtained, when the reaction was carried out in EtOH. Further transformations from furoxans to multifunctional blasting materials furazans, structural modifications of natural products and a gram-scale reaction proved the potential applications of this method.