Nitro groups displacement

Compound 432, which can be easily prepared from trinitrochlorobenzene (76), treated with triethylamine in dipolar aprotic solvents provided good yield of the denitrocyclization product 433 (80JCS(P1)2205). Reaction of 2,3,5,6-tetra-chloronitrobenzene (434) with various 1,2-diamines under high pressure provided mixtures of the corresponding open products of the nitro group displacement, e.g. 435, and cyclized products, e.g. 436 (Scheme 69). Compound 436 was formed by denitrocyclization reaction, since compound 435 did not cyclize under the used conditions (94BCJ196, 95BCJ3227). 

Highly electron-deficient 1,3,6,8-tetranitronaphthalene 443 was reported to react in ethanol with A -methyl phenylacetamidines, e.g. 444, to give the corresponding benzoquinoline derivatives, e.g. 446 (77JOC435). Though the reaction mechanism of this double nitro group displacement is not known, formation of intermediate 445 and its following cyclization is probably the most reasonable explanation (Scheme 70). 

Hydride adducts (31) may be formed by the reaction of 1,3-dinitrobenzene with potassium borohydride their treatment with phenyldiazonium salts leads to nitro group displacement yielding azo-coupled products (32). 

Alkoxylation in the benzene ring of quinazolines and quinazolinones is readily achieved in the presence of an ortho-nitro group, and even in the absence of a nitro group, displacement of fluorine is still quite facile. Examples of haloquinazolines to have been alkoxylated include 5-chloro-8-nitro-4(3//)-quinazolinone 187 <2005BMC5613>, 7-chloro-6-nitro-4(377)-quinazolinone 188 <1996JME267>, 4-arylamino-7-fluoro-6-nitroquinazolines 189... 

The replacement of the nitro group by fluorine in aliphatic compounds appears to be much less well known than in the aromatic series. The possibility of nitro group displacement in aromatic compounds was noted during the study of halide displacement in halo-substituted 2,4-dinitrobenzenes. The appearance of brown fumes and formation of traces of lower boiling products resulted in studying the exchange of the nitro group in 2,3,5,6-tetrachloro-l-nitroben-... 

To facilitate the nitro group displacement reaction, the thioethers 7, obtained by treatment of difluoride 6 with thiols, were oxidized with 3-chloroperbenzoic acid to afford the corresponding sulfones 8 (Fig. 4). The resulting sulfones 8 showed the expected high reactivity toward nucleophiles, as demonstrated by the efficient displacement of both the second fluoride and the nitro group with two different aliphatic amines to yield the highly substituted benzamides 10. 

Reaction of 1,3,5-trinitrobenzene (TNB) with o-aminophenols in the presence of potassium carbonate in dipolar aprotic solvents has been shown to produce 1,3-dinitrophenoxazines (5). This reaction is thought to involve nitro group displacement to yield intermediates (4), which undergo oxidative substitution of hydrogen by the amino group.18 The corresponding reaction of TNB with o-aminothiophenols yields 1,3-dinitrophenothiazine derivatives. 

Methoxy-4-nitropyridazines react with alkyl iodides at about 100°C to give esters of cyclic hydroxamic adds [Eq. (23)] resulting fi om methylation, demethylation, and nitro group displacement. A 6-methyl group is transformed into a ( ano group by the nitrous add produced. ... 

Diphenylamines may be prepared by nitro group displacement from o- or p-dinitrobenzenes or from cyano-substituted nitrobenzenes. Thus, reaction with acidic anilines containing electron-withdrawing substituents in DMSO in the presence of potassium carbonate yields [234] products such as (88). Orf/jo-dinitrobenzene will also react with tervalent phosphorus compounds, such as trialkylphosphites, in acetonitrile to give substituted products (89) is formed from trieth-ylphosphite [235]. 

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