5(6)-Fluoro-6(5)-R-benzofuroxans: synthesis and NMR , and studies

Kotovskaya, S. K.; Romanova, Svetlana A.; Charushin, Valery N.; Кодесс, М. И.; Чупахин, О. Н.

doi:10.1016/j.jfluchem.2003.11.011

Cited by 26 publications

(15 citation statements)

References 12 publications

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“…To understand better the influence of the position of the fluorine atom on the reactivity and electrophilicity of polyfluorobenzo‐furoxan and ‐furazan, the syntheses of known 5‐fluoro‐ ( 24 ),34 5,6‐difluoro‐ ( 25 ),35 and 4,5,6‐trifluoro‐benzofuroxan ( 26 )13 were performed. To complete this study, the syntheses of the new benzofurazan analogues 27 – 29 of the previous heterocycles were carried out (Scheme ).…”

Section: Discussionmentioning

confidence: 99%

Revisiting the Synthesis of 4,6‐Difluorobenzofuroxan: A Study of Its Reactivity and Access to Fluorinated Quinoxaline Oxides

et al. 2014

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New quinoxaline 1,4‐dioxide derivatives have been synthesized from novel fluorinated benzofuroxans such as 4‐fluorobenzofuroxan, which is prepared for the first time. Furthermore, the preparation 4,6‐difluorobenzofuroxan has been revisited because we were unable to reproduce the reported synthetic method. Several synthetic pathways have thus been investigated, and the optimal way to prepare this disubstituted benzofuroxan was from the 3,5‐difluoro‐2‐nitroaniline. The various synthetic attempts have allowed the isolation of interesting new compounds such as hydroxybenzotriazole‐like heterocycles or benzoquinone 2‐diazide. In the latter case, our study reveals some interesting features in the mechanism of their formation. The first structural elucidation of benzoquinone 2‐diazide through an X‐ray crystallographic study is also reported. This study has unambiguously shown that benzoquinone 2‐diazide can be involved in Diels–Alder reactions. The first case of a reaction involving a nitro‐substituted benzoquinone 2‐diazide and cyclopentadiene is also reported. To understand better the influence of the fluorine atoms on the reactivity of benzofuroxans and benzofurazans, a wide array of new fluorinated heterocycles were synthesized together with some already known compounds. This has enabled an extensive investigation of their electrophilic behavior to be undertaken through a theoretical and an electrochemical study. From these studies, it could be deduced that the replacement of nitro groups by fluorine atoms results in a significant decrease in the electrophilic character of benzofuroxan. Nevertheless, these compounds could undergo SNAr processes, leading to new functionalized heterocycles. The first examples of aromatic nucleophilic substitution of fluorine with these compounds are also described.

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Section: Discussionmentioning

confidence: 99%

Revisiting the Synthesis of 4,6‐Difluorobenzofuroxan: A Study of Its Reactivity and Access to Fluorinated Quinoxaline Oxides

et al. 2014

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“…With the exception of the 13 C NMR of 6d, which was obtained on a Bruker 600 MHz instrument, all NMR spectra were recorded on a Varian Unity+300 instrument at ambient temperature. Chemical shifts for 19 F NMR were measured from hexafluorobenzene as internal standard and converted to the d-scale with CFCl 3 as reference by the conversion relation d(CFCl 3 ) = d(C 6 F 6 ) À 162.9 ppm [23]; spectra exhibiting 19 F-19 F coupling were run with acquisition time = 1.0 s to improve resolution. GC-MS data were obtained on a Shimadzu GC-17A/QP-5000 instrument operating in EI mode (70 eV).…”

Section: Methodsmentioning

confidence: 99%

Nuclear fluorination of 3,5-diarylisoxazoles with Selectfluor®

Stephens

Blake

2004

Journal of Fluorine Chemistry

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“…Fluorinated Benzofuroxanes. The factors affecting tautomeric equilibria as well as thermodynamic characteristics of both isomers have been determined (Scheme 4) [17,18]. The factors affecting tautomeric equilibria as well as thermodynamic characteristics of both isomers have been determined (Scheme 4) [17,18].…”

Section: Discussion Fluorinated Benzazolesmentioning

confidence: 99%