One-Pot Synthesis of Highly Functionalized Bicyclic Imidazopyridinium Derivatives in Ethanol

A concise and eco-friendly route for the synthesis of highly functionalized bicyclic pyridinium derivatives (3) via a one-pot reaction of chromone-3-carboxaldehydes (1) and N-benzyl nitro ketene aminals (NBNKAs) (2) under reflux in ethanol media has been developed. The targeted compound was efficiently obtained by filtration without further post-treatment. In the one-pot two step reaction, CC and CN bonds were constructed, while at the same time one CO bond was cleaved. This protocol represents a valuable route to obtain highly functional bicyclic pyridinium derivatives in a concise, rapid, and practical manner. The reaction is particularly attractive due to features such as low cost, mild conditions, atom economy, high yield, using biocompatible solvent, and potential biological activity of the product.