A Synthetic Pathway to Substituted Benzofuroxans through the Intermediacy of Sulfonates: The Case Example of Fluoro‐Nitrobenzofuroxans

Benzofuroxans are well known compounds that continue to attract particular attention since the discovery of 4,6‐dinitrobenzofuroxan (DNBF) back in 1899. It has been shown that these compounds possess biological activities that are related to their electronic behaviours and the positioning of substituents borne by the heterocycles. In this paper, we report the first synthesis of 4‐fluoro‐6‐nitrobenzofuroxan and 6‐fluoro‐4‐nitrobenzofuroxan; the altered positions of the substituents enabling us to carry out structural and reactivity comparisons, with DNBF and 4,6‐difluorobenzofuroxan. These compounds have been unambiguously characterized through NMR and radiocrystallographic studies. Two main synthetic pathways involving fluoroanisoles and fluorophenols, cheap and easily available chemicals, have been successfully developed. Finally, benzofurazan analogues have been prepared via deoxygenation of corresponding benzofuroxans with triethylphosphite.