Nitration of 5-fluoro-2,1,3-benzoselenadiazoles, and the synthesis of 4-fluoro3-nitro-, 4-fluoro-6-nitro-, 5-fluoro-3-nitro-o-phenylenediamines and 3,4-diamino-2-nitrophenols by subsequent deselenation
Fuming nitric and concentrated sulfuric acids converted the title benzoselenadiazoles 1 and 8 into their 4- and/or 7-nitro derivatives. Unlike the m-fluoronitro substituted products 6 and 9, the o-fluoronitro substituted products 2 were accompanied by the corresponding benzoselenadiazol-5-ols 3. These were formed by hydrolysis in amounts increasing with the reaction time. ipso-Nitration of 8 was followed by instantaneous hydrolysis to benzoselenadiazol-5(4H)-one (R,S)-11. Reductive ring opening of the nitration products 2, 6, 9 and 3 with hydriodic acid yielded the corresponding novel fluoronitro-o-phenylenediamines 4, 7, 10 and o-nitrophenols 5 in 70–80% yield.