Unexpected Cleavage of N‐N Bonds of Pentafluorophenylhydrazones – Formation of Nitriles by a Radical Fragmentation Reaction. Issue 13 (2nd April 2020)

• Record Type: Journal Article
• Authors: Bortňák, Dušan; Milata, Viktor; Šofranko, Jakub; Végh, Daniel; Prousek, Josef; Barbieriková, Zuzana; Breza, Martin; Brezová, Vlasta; Dvoranová, Dana; Šoral, Michal
• Is Part Of: ChemistrySelect. Volume 5:Issue 13(2020)
• Page Start: 3929
• Page End: 3933
• Publication Date: 2020-04-02
• Subjects: Cleavage reactions -- Fluorine -- Hydrazones -- Nitriles -- Radical reactions; Chemistry -- Periodicals; 540.5
• DOI: 10.1002/slct.202001055
• Languages: English
• ISSNs: 2365-6549

Abstract

Abstract: 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. Abstract : The reactivity of organic compounds is often bizarre and surprising given the chemist's expectations. If seemingly unsuccessful reaction mixtures are studied instead of being discarded, new interesting reaction pathways can be discovered. In this case, instead of an expected nucleophilic substitution reaction between a set of pentafluorophenylhydrazones and sodium azide, a novel radical fragmentation reaction provided corresponding nitriles.