4.6- Dinitrobenzofuroxan derivatives

The applications of 1,2,5-oxadiazole iV-oxide and benzo[c][l,2,5]oxadiazole iV-oxide derivatives as compounds which have herbicidal activity are known. For example, the most active compound, butylcarbamoylbenzoL] 1,2,5-oxadiazole iV-oxide, displayed herbicidal activity at concentrations as low as 24 gha-1 <2000JFA2995>. The preparation of 5,7-disubstituted 4,6-dinitrobenzofuroxane derivatives (2-chlorophenylamino, 2,5-dichlorophenyl-amino, 2-hydroxyphenylamino, or 4-bromophenylamino), which are useful as agricultural arachnicides and bactericides, was described <2005RUP2255935>. 

Sulfanilamides Pharmaceutical formulation and blood As 4,6-dinitrobenzofuroxane derivatives... 

The photometric determination of mixtures of aniline, p-nitroaniline and o-nitroaniline was described. Distribution coefficients and separation efficiency of these compounds by LLE in various solvents were compared517. Substituted nitroanilines such as 2-chloro-4-nitroaniline and 2,4-dinitroaniline are intermediates in the manufacture of the dye D C Red No. 36 and were identified as impurities by RP-LC518. A spectrophotometric method was developed for the determination of aniline and m-nitroaniline in a mixture of aniline and nitroaniline isomers by derivatization with 5,7-dichloro-4,6-dinitrobenzofuroxan (244). The relative error of the determination is <5%519. See also Section IV.D.3.b for similar derivatives. 

Some nitro derivatives of benzofurazan have been investigated for their explosive properties. 4-Amino-5,7-dinitrobenzofurazan (56) has been prepared by a number of routes including (1) the thermally induced cyclodehydration of l,3-diamino-2,4,6-trinitrobenzene (55), (2) the nitration of 4-amino-7-nitrobenzofurazan and (3) the reduction of 4-amino-5,7-dinitrobenzofuroxan with triphenylphoshine. The isomeric 5-amino-4,7-dinitrobenzofurazan (57) has been prepared along similar routes. ... 

Nitration at the 4-position occurs readily and further reaction gives the 4,6-dinitro derivatives. 5-Substituted analogues react similarly, 5-chlorobenzofuroxan affording the 4-nitro-5-chloro compound and subsequently 5-chloro-4,6-dinitrobenzofuroxan <84H(22)27i>. In such cases the isolated product may be the 7-substituted-4,6-dinitro compound due to rearrangement of the first-formed derivative (see Section 4.05.5.1.4). 

Although the tendency of benzofuroxan derivatives to interact with electron donors has been known since Drost s early report197 199 firm experimental evidence on the formation of Meisenheimer adducts was not reported until the 60s for the reaction of 4,6-dinitrobenzofuroxan with RO nucleophiles200 202 (Eq. 25). Information on benzofurazans became available even later with an NMR study by Terrier, Simonnin, and their co-workers.203... 

Note Compare with info on Dinitrobenzofuroxan under Benzofuroxan and Derivatives... 

There have been several studies utilizing the ability of 4,6-dinitrobenzofuroxan (DNBF) to act as a super-electrophile. It has been shown that the initial product of its reaction with phenoxide ions is the O-bonded adduct (29), although this rearranges to give die C-bonded adduct.117 The reaction of DNBF with ethyl vinyl ether yields a dihydrooxazine A -oxidc cycloadduct as a mixture of two diastereoisomers, and in the presence of excess ether a di-adduct (30) is formed.118 Rate constants have been reported for the reaction of DNBF with 3-methoxythiophene in DMSO-water mixtures. The reaction results in a er-adduct which is the product of Se-At substitution in the thiophene, and the results were used to probe the carbon basicity of the thiophene derivative.119... 

Dinitrobenzofuroxan (DNBF) is known as a superelectrophile due to its high reactivity both as an electrophile and in its pericyclic addition reactions. NMR studies show that reaction with 2-aminothiazole and its 4-methyl derivative yield anionic carbon-bonded adducts such as (11) by reaction at the 5-position, whereas the 4,5-dimethyl derivative reacts via the exocyclic amino group. Kinetic studies of the first two compounds, both in acetonitrile and in 70 30 (v/v) water-DMSO, have been used to assess their carbon nucleophilicities and place them on the Mayr nucleophilicity scale.55 In a related study, the nucleophilic reactivity, in acetonitrile, of a series of indoles with both DNBF and with benzhydryl cations have been compared and used to determine nucleophilicity parameters for the indoles.56... 

Aminothiazole and its 4-methyl derivative react with the superelectrophilic 4,6-dinitrobenzofuroxan at C(5) to form, for example, (1) in spite of them exhibiting higher nitrogen basicity than aniline.7 In the case of 4,5-dimethyl-2-aminothiazole, however, attack did occur at nitrogen. 

This study reports on the reactions of ambident nucleophiles with electron-deficient nitroaromatic and heteroaromatic substrates anionic complex formation or nucleophilic substitution result. Ambident behavior is observed in the case of phenoxide ion (O versus C attack) and aniline (N versus C attack). O or N attack is generally kinetically preferred, but C attack gives rise to stable thermodynamic control. Normal electrophiles such as 1,3,5-trinitrobenzene or picryl chloride are contrasted with superelectrophiles such as 4,6-dinitrobenzofuroxan or 4,6-dinitro-2-(2,4,6-trinitrophenyl)benzotriazole 1-oxide (PiDNBT), which give rise to exceptionally stable a complexes. Further interesting information was derived from the presence in PiDNBT of two electrophilic centers (C-7 and C-l ) susceptible to attack by the ambident nucleophilic reagent. The superelectrophiles are found to exhibit lesser selectivity toward different nucleophilic centers of ambident nucleophiles compared with normal electrophiles. 

Hydroxide ion replaces the methoxide of 7-methoxy-4-nitrobenzofuroxan to form the 7-hydroxy-4-nitro compound, which rearranges to the 5-hydroxy-4-nitro derivative, under certain conditions.418 Buncel et al.501 have also described the demethylation of 7-methoxy-4,6-dinitrobenzofuroxan by methoxide ion. 

The SNAr reactions of heteroarenes can be realized in a similar manner, as in the series of arenes [71, 82]. These nucleophilic reactions are analogous to electrochemical Sn transformations of arenes [22, 24, 25]. Terrier and co-workers considered an opportunity for electrochemical methoxylation of 4,6-dinitrobenzofuroxan by action of the methoxide ion via the SnAt mechanism [21]. The intermediate o -complex formed was oxidized successfully into the corresponding substitution product. Analogously, the formation of heteroaromatic amines has been suggested to occur via intermediacy of the corresponding amino adducts, as exemplified by the oxidation of the o -complex derived fi om the reaction of pyrimidine with NH2 (Scheme 26) [3, 102-104]. 

When methanol is used instead of an aqueous environment, potassium salts of methoxy derivates of dinitrobenzofuroxan or dinitrobenzofurazan (depending on reaction conditions) form instead of KDNBF [7]. 

Sinditskii, V.P., Egorshev, V.Y., Serushkin, V.V., Margolin, A.V., Dong, H.W. Study on combustion of metal-derivatives of 4,6-dinitrobenzofuroxan. hi Proceedings of 4th International Autumn Seminar on Propellants, Explosives and Pyrotechnics, pp. 69-77, Shaoxing, 2001... 

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