2‐Aryl‐3‐Vinyl Substituted Imidazo[1,2‐a]pyridines and Fluorescent Electrocyclization Derivatives therefrom

• Published in: ChemistrySelect (Weinheim) 2020-04, Vol.5 (15), p.4552-4558
• Main Authors: Benzi, Alice, Bianchi, Lara, Giorgi, Gianluca, Maccagno, Massimo, Petrillo, Giovanni, Tavani, Cinzia
• Format: Article
• Language: English
• Subjects: electrocyclic reactions; fluorescence; imidazopyridines; Michael addition; polyheterocycles
• ISSN: 2365-6549; 2365-6549
• DOI: 10.1002/slct.201904950

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. We are here describing a metal free, very simple access to pharmaceutically important imidazopyridines derivatives, from which interesting fluorescent polyheterocycles can be originated thanks to a photostimulated tandem process.