Study of reactions of pentafluorophenylhydrazine with activated enolethers. Synthesis of N-pentafluorophenylpyrazoles

Bortňák, Dušan; Šoral, Michal; Breza, Martin; Vlčková, Silvia; Végh, Dániel; Milata, Viktor

doi:10.24820/ark.5550190.p009.659

Cited by 3 publications

(1 citation statement)

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“…Hydrazones are very useful intermediates in organic synthesis 1 for their possible broad application 2 . In continuation of our previouswork (synthetic exploitation of pentafluorophenylhydrazine), where we demonstrated its different reactivity in comparison with phenylhydrazine with 3‐oxo‐2‐ethoxymethylenebutanenitrile 3 or its reactions with various β,β‐activated enolethers 4 or in Clauson‐Kaas reaction, 5 we decided to study nucleophilic substitution of the azide anion with various pentafluorophenylhydrazones 1 listed in Table 1 (Figure 1).…”

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confidence: 99%

Mass spectrometrical and quantum‐chemical study of pentafluorophenylhydrazones

et al. 2020

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Twenty-one pentafluorphenylhydrazones have been analyzed by means of tandem mass spectrometry (ESI MS/MS) conditions to compare their fragmentations with those ones obtained from quantum-chemical calculations of the hydrazone moiety depending on the substitution from the aldehyde site. The hydrazone N-N bond is disrupted under such conditions, and these results are in accordance with the facts that an electron-rich particle, such as an anion and or radical in a solution, can cause this disruption and simultaneous defluorination in para-position of the hydrazone part of the molecule.

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Section: Introductionmentioning

confidence: 99%

Mass spectrometrical and quantum‐chemical study of pentafluorophenylhydrazones

et al. 2020

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Unexpected Cleavage of N‐N Bonds of Pentafluorophenylhydrazones – Formation of Nitriles by a Radical Fragmentation Reaction

et al. 2020

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A novel method of the preparation of (hetero)aryl nitriles based on the fragmentation of the corresponding pentafluorophenylhydrazones is described. The synthesis is metal‐free, proceeds in neutral conditions with no need of protecting group application and provides most nitriles in moderately good yields. The synthesis was performed on ten pentafluorophenylhydrazones with different functional groups within the carbonyl part – the reaction was found to be partially substrate selective. The reaction prefers substrates with aromatic electron donating substituents on the carbonyl part of the hydrazone. The second reaction product, 2,3,5,6‐tetrafluoroaniline, can be easily separated by vacuum distillation. Although the reaction mechanism is yet to be ascertained, all synthetic and spectroscopic data suggest a radical reaction mechanism.

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