NOBF4 underbasic or even almost neutral reaction conditions. Acid-sensitive functional groups are tolerated under the developed basicconditions. For the substrates having poor reactivity, almost neutralconditions (using pyridine equimolar to NOBF4) are suitable for better yields. Furoxans (1,2,5-oxadiazole 2-oxides) can be synthesized from the corresponding styrenes using NOBF4 underbasic or even
corresponding styrenes usingnitrosoniumtetrafluoroborate as the nitrosation reagent in pyridine (basic media) or dichloromethane (neutral media). Acid‐sensitive functional groups were tolerated under these conditions. The probable reaction mechanism was elucidated. The experimental results support an ionic reaction pathway in contrast to the conventional acidic conditions with a radical mechanism.