Nitro ring fission

The direct nitration of 2-amino-4-methylselenazole leads to a ring fission. However, if the amino group is previously acetylated, the corresponding 5-nitro compound is formed in good yield 2-acetamido-4-methyl-5-nitroselenazole, mp 185°C. ... 

Details of the mechanism have revealed the role of Meisenheimer-type hydride complexes, which is consistent with the presence of the strongly electron-withdrawing nitro groups that facilitate what are formally hydride reductions involving reduced coenzyme F420 (Ebert et al. 1999). For example, 2,4,6-trinitrophenol is reduced successively by hydride transfers catalyzed by F420, followed by loss of nitrite, further reduction, and ring fission to 4,6-dinitrohexanoate (Hofmann et al. 2004). 

Methylamiuomethylindole. The reaction of 2-methyl-5-nitroisoquinolinium iodide (1) with TiCla (7.7 equiv.) gives 4-methylaminomethylindole (2) directly in 20% yield. The conversion proceeds via reduction of the nitro group to an amino group, ring fission, and recyclization. 

The triazole forms by combination of ring-fission products with hydrazine. Similar reactions of hydrazine with 2-nitroimidazoles in the presence of palladium-carbon result in reduction of the nitro group <84JOC932>, while 1-methylbenzimidazole-3-oxide gives 2-hydrazino-l-methylbenzimidazole... 

Vinyl chloride,29 vinyl acetate,30 oc-nitro olefins,31 and azlactones32 also add alkanethiols. The reaction of azlactones is accompanied by ring fission to yield V-acyl / -alkylthio oc-amino thioesters, this being a good preparative route to such compounds ... 

DiaryInitrosamines undergo fission at the nitrogen-nitrogen bond upon heating (3T>38) In the presence of oxygen, the ring nitro substituted amines are obtained (3T) in the absence of... 

Sulfonation of nitroso compounds by sodium hydrogen sulfite leads to amino sulfonic acids by simultaneous reduction.1240 194 When aromatic nitro compounds are subjected to this reaction, sulfonation in the ring is accompanied by formation of arylamine-JV-sulfonic acids (arylsulfamic acids), which on acid fission also give amino sulfonic acids this reaction, known in the literature as the Piria reaction, has been reviewed in papers by Hunter and his co-workers.195... 

The aldehyde group stabilizes the furfural stmcture against the acid-catalyzed fission of the furan ring that readily occurs in furan and alkyl furan derivatives. Basic-type stabilizers, such as tertiary amines, can be used to inhibit oxidation of the furan structure [3]. Furfural can be oxidized to furoic acid or reduced to furfuryl alcohol which can be converted to furan by a catalyzed decarbonylation reaction. On an industrial scale furfural is the source for furfuryl alcohol, tetrahydrofurfuryl alcohol, furan, and tetrahydrofuran. Nitro-furan compounds derived from furfural are used as bactericides in humans. 

So far we have discussed simple bond fission in which only one bond is broken. In this section we discuss decomposition pathways in which multiple bonds are broken and formed simultaneously In particularly, we present results for five-centered HONO elimination from nitro compounds containing a [3-hydrogen as well as results for concerted decomposition of six-membered ring compounds. 

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