Imidazo[1,2-b]pyridazines and an imidazo[l,2-a]pyrazine from pyridazin- and pyrazin-amines

Abstract

The ambiguous condensations of phenylglyoxal with pyridazin-3-amines and pyrazin-2-amine are shown to yield 2-phenylimidazo[l,2-b]pyridazin-3(5H)-ones and imidazo[1,2-a]pyrazin-3(7H)-one, respectively. The former products exist as such, at least in the solid state, whereas the latter product exists to a large extent as the corresponding dipolar molecule. The reactions, degradations and n.m.r. spectra of the products are discussed.