First synthesis of the N(1)-bulky substituted imidazole 3-oxides and their complexation with hexafluoroacetone hydrate

Synthesis of new 2-unsubstituted imidazole 3-oxides bearing bulky substituents at the N(1) atom, based on the condensation of appropriate alkylamines, formaldehyde, and corresponding α(hydroxyimino)ketone, is described. Treatment of imidazole 3-oxides with hexafluoroacetone hydrate (HFAH) yields crystalline 1:1 complexes in nearly quantitative yields. Heating of isolated complexes possessing phenyl ring at the C(4) atom of imidazole ring, results in their isomerization into imidazol-2-ones in fair yields. The formation of analogous complexes of HFAH with other azole N-oxides is also described.