Simple synthesis of imidazo[1,2-A]pyridine derivatives bearing 2-aminonicotinonitrile or 2-aminochromene moiety

Abstract

A simple and general method for the synthesis of new imidazopyridines bearing an aminopyridinyl, chromenyl, or quinolinyl moiety in the C2 position was developed. The Knoevenagel reaction between imidazo[1,2-a]pyridine-2-carbaldehyde 1 and malononitrile resulted in the formation of starting material 2. Subsequently, intramolecular cyclization between the cyano group of 2 and acetophenones, naphtols, hydroxyquinolines, or phenols, gave 3, 4, 5, and 6 compounds, respectively. This is a simple, reproducible, and environmentally friendly method of synthesizing substituted imidazopyridines using water as a solvent or under solvent-free conditions.

Graphical Abstract

Keywords:

• Aminochromene
• aminopyridine
• green chemistry
• imidazopyridine
• Knoevenagel

Acknowledgment

The authors thank V. Remusat for NMR spectra recording and the Spectropole team for various analytical measurements.

Additional information

Funding

This work was supported by the CNRS (Centre National de la Recherche Scientifique), Aix-Marseille University and Houari Boumediene University of Sciences and Technology.