Synthesis and study of prototropic tautomerism of 2-(3-chromenyl)-1-hydroxyimidazoles

A series of novel derivatives of imidazole containing a chromenyl moiety in position 2 of the ring has been synthesized. A characteristic response of the chromenyl ring H-2 proton to its environment allows the study of the prototropic tautomerism of novel 1-hydroxyimidazoles in solution using 1H NMR spectroscopy. It has been shown that the predominance of one or another tautomer depends on the nature of the substituents of the imidazole ring, and the proton-donating/proton-withdrawing properties of a solvent. X-ray diffraction data for two of the compounds has revealed that in the solid state these 1-hydroxyimidazole derivatives exist as N-oxide tautomers.