The crystal and molecular structure of 4,6-dinitrobenzfuroxan

Prout, C. K.; Hodder, O. J. R.; Viterbo, D.

doi:10.1107/s0567740872004522

Cited by 23 publications

(13 citation statements)

References 3 publications

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“…This is also typical of a nitro-olefinic fragment as it was reported for DNBF 1 where values of 1.370 and 1.400 Å have been measured for the two potentially reactive C 6 =C 7 and C 4 = C 5 double bonds, respectively. [22] This first experimental finding reflects the low degree of aromatic character for the benzo- furoxan structure as has been previously demonstrated for other substituted benzofuroxans. [23] That the signals corresponding to benzofuroxan 9 are unresolved provides clear evidence of the well-known 1-oxide/3oxide tautomeric relationship.…”

Section: ) Structural Study Of Benzofuroxans 9 and 10supporting

confidence: 66%

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

et al. 2016

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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.

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Section: ) Structural Study Of Benzofuroxans 9 and 10supporting

confidence: 66%

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

et al. 2016

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“…Evidence for the importance of this structure is provided by theofinding by X-ray crystallography that the C8Nl bond (1.40 A) is appreciably longer than the C9N3 bond (1.37 A) (15).…”

Section: C Chemical Sh$s and Coupling Constants Ofdnbf Anddnbzmentioning

confidence: 99%

“…DNBF was thus formulated as l a on the basis that steric, electrostatic, and mesomeric effects are expected to cause the equilibrium l a l b to lie very predominantly on the side of the isomer l a (10,11,14). Interestingly, l a was later found by an X-ray crystallography study to be the structure of DNBF in the solid state (15). Another interesting observation of Katritzky dealt with the solvent dependence of the AX or AB pattern, but no attempt to assign the HA and HB (Hx) resonances to the H-7 and H-5 protons of l a was made (14).…”

Section: 'H Chemical Shifts Of Dnbf and Dnbzmentioning

confidence: 99%

A structural reinvestigation of 4,6-dinitrobenzofuroxan by ¹H, ¹³C, and ¹⁵N nuclear magnetic resonance

Terrier¹,

Hallé²,

MacCormack³

et al. 1989

Can. J. Chem.

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A detailed nuclear magnetic resonance study of 4,6-dinitro-2,1,3-benzoxadiazole N-oxide (DNBF), which includes a 2D INADEQUATE analysis and experiments with samples 15~-labelled at the NO2 groups, is described. The results lead to an unambiguous assignment of the carbon and proton chemical shifts in various solvents. Some 'H and I3C data pertaining to 4,6-dinitro-2,1,3-benzoxadiazole (DNBZ), the deoxygenated analog of DNBF, are also reported, allowing the influence of the N-oxide group on the proton and carbon chemical shifts to be discussed. It is shown that all of the 'H nmr evidence so far reported for the characterization of DNBF a adducts as arising from nucleophilic addition to the 7-position, i.e., as structure 2a, has no significance. That complexation actually occurs at this position is, however, convincingly demonstrated by "N data. These also allow us to establish that this process is both kinetically and thermodynamically favored.

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“…It is of interest to note that the NO 2 group is near to the N2 of the furoxan heterocycle, the N2-O3 distance being 2.72 Å in WM8. Accordingly, these compounds are prone [38] to the Boulton-Katritzky rearrangement. [39] Even if it is reasonable to think that the first evolution of WM8 is the shift of the proton from the C7 atom of the thiazole ring to a more basic centre, probably the N3 atom (and the corresponding shift of the proton bound to the C5 atom of the thiazole ring to the N7 atom in WM9), we have no evidence (in either case) for the presence of a zwitterionic σ complex ZW.…”

Section: Resultsmentioning

confidence: 99%

Trapping and Analysing Wheland–Meisenheimer σ Complexes, Usually Labile and Escaping Intermediates

et al. 2011

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The reactions between 2,4-dipyrrolidin-1-yl-1,3-thiazole, a supernucleophilic reagent, and 4,6-dinitrobenzofuroxan (DNBF) or 4,6-dinitrotetrazolopyridine (DNTP), two superelectrophilic reagents, afforded new covalent complexes that are contemporaneously intermediates of an S N Ar reaction (a Meisenheimer complex) and of an S E Ar reaction (a Wheland complex). These compounds belong to a new class of covalent complexes, which we have named Wheland-Meisenheimer complexes (WM). The high stability of the complexes reported herein allowed the first X-ray diffraction analyses of WM complexes. In addition, the reactions are diastereoselective, probably because of the specific approach of

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The crystal and molecular structure of 4,6-dinitrobenzfuroxan

Cited by 23 publications

References 3 publications

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

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

A structural reinvestigation of 4,6-dinitrobenzofuroxan by ¹H, ¹³C, and ¹⁵N nuclear magnetic resonance

Trapping and Analysing Wheland–Meisenheimer σ Complexes, Usually Labile and Escaping Intermediates

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The crystal and molecular structure of 4,6-dinitrobenzfuroxan

Cited by 23 publications

References 3 publications

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

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

A structural reinvestigation of 4,6-dinitrobenzofuroxan by 1H, 13C, and 15N nuclear magnetic resonance

Trapping and Analysing Wheland–Meisenheimer σ Complexes, Usually Labile and Escaping Intermediates

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A structural reinvestigation of 4,6-dinitrobenzofuroxan by ¹H, ¹³C, and ¹⁵N nuclear magnetic resonance