2-Aryl-3-Vinyl Substituted Imidazo[1,2-a]pyridines and fluorescent electrocyclization derivatives therefrom

A collection of 2-aryl-3-vinylimidazo[1,2-a]pyridines, substituted on the pyridine ring and/or the aryl substituent, can be obtained by reaction of 2-aminopyridines with properly substituted nitrobutadienes, originated by an initial ring opening of a nitrothiophenic precursor. Although the aza-Michael addition of 2-aminopyridine on a nitrovinyl moiety is the starting point of classic approaches to imidazopyridines, the final structures generated herein are the result of a cascade process made possible by the particular functionalization on the conjugated systems. Beside the general interest inherent to the pharmacologically versatile imidazo[1,2-a]pyridine structural motif, the substituents present in the obtained compounds allow specific synthetic elaboration to e. g. polycyclic fluorescent heterocycles.