Retro-aza-Henry-type conversion of β-nitrostyrenes to the related hydrazones using ascorbic acid-functionalized graphene as a catalyst

Abstract

In a present report, a new method is developed for the conversion of β-nitrostyrenes and β-methyl-β-nitrostyrenes to their related hydrazones via a retro-aza-Henry-type conversion. Ascorbic acid-modified graphene oxide was used as an inexpensive, biocompatible, and metal-free catalyst for this reaction which catalyzed the reaction including the C=C double-bond breaking. Via this reaction, 20 different nitroolefin derivatives were successfully converted to the related hydrazones using 3 equivalents of hydrazine hydrate, 3 mL ethanol as a solvent, and 0.01 g catalyst in 4 h at room temperatures. The obtained yields were excellent and it was between 85 and 100% using both electron-releasing and electron-withdrawing groups in different positions. Moreover, the existence of methyl group at the beta position of the β-nitrostyrenes has no negative effect on the reaction. The synthesized catalyst showed appropriate recoverability, with only a 15% reduction in its efficiency after four runs.

Graphical abstract