Investigation of N–NO2→C–NO2 rearrangement of 2-nitroaminothiazoles by carbon-13 and nitrogen-15 nuclear magnetic resonance

Abstract

The amino ⇌ imino tautomerism of 2-aminothiazoles and their salts has been studied. It has been established that in the acid-catalysed nitramin rearrangement of 2-nitroaminothiazoles the seconds protonation of the compounds protonated at the exo-nitrogen atom in concentrated sulphuric acid initiates the cleavage of the nitro group. The intermediate exits also in salt from, in which the nitro group is attached to the N(3) atom. The slow protonation results in the heterolytic fission of net N(3)–NO₂ bond, which is followed by the formation of the 5-nitro final product via a σ-complex.