Utilizing radical chemistry, a new general C–C bond formation on the furoxan ring was developed. By taking advantage of the lability of furoxans, a wide variety of transformation of the synthesized furoxans have been demonstrated. Thus, this developed methodology enabled not only the modular synthesis of furoxans but also short-step transformations of carboxylic acids to a broad range of functional groups.

Furoxans are potentially useful heteroaromatic units in pharmaceuticals and agrichemicals. However, the applications for furoxan-based compounds have been hampered due to the underdevelopment of their synthetic methods. Herein we report a new synthetic approach for the synthesis of chloro-and bromofuroxans. The starting materials were dichloro-and dibromofuroxans, and the substituents were directly introduced to the furoxan ring in a modular fashion. The synthesized monohalofuroxans served as substrates for the installation of a second substituent to prepare further functionalized furoxans.

A C–C bond forming method was developed, whereby a furoxan ring is incorporated into various types of C–H bonds. The protocol not only offers a concise synthetic route to a variety of alkylated furoxan derivatives but also provides an efficient strategy for the insertion of various nitrogen-containing functional groups into C–H bonds via transformation of the resultant furoxan ring.