Base-catalysed rearrangement of 2-phenylamino-1,3,4-oxadiazole into 4-phenyl-1,2,4-triazolin-5-one

Abstract

The behaviour in alkaline media (water, water–dioxane, or water–dimethyl sulphoxide) of 2-phenylamino-1,3,4-oxadiazole (IH) has been studied, together with the title reaction. Chemical and kinetic evidence support the occurrence of a ring conversion through an intermediate cyclic compound (IV^–), followed by the formation of an open-chain anion (V^–) that cyclizes fast to the triazole derivative (III^–).