Three-ring tautomerism of the Δ2-isoxazoline - Δ2-pyrazoline - 1,3,4-thiadiazine system

Abstract

The tendency to tautomeric equilibria of 5-(2-mercaptoacetylhydrazine)-3,5-dimethyl-∆ 2 -isoxazoline in solutions with the participation of not only the isoxazoline ring but also of ∆ 2 -pyrazoline and 1,3,4-thiadiazin-5(6H)-one forms was confirmed by 1 H and 13 C NMR spectroscopy. A new type of tautomeric transformations involving three different rings was found.