NaNO2/I2‐Mediated Regioselective Synthesis of Nitrosoimidazoheterocycles from Acetophenones by a Domino Process

Abstract

A regioselective synthesis of nitrosoimidazoheterocycles from the reaction of 2‐aminopyridines and acetophenones in the presence of NaNO2 and I2 is described. The reaction is suggested to proceed by a domino process involving sequential imine formation, iodination, iodide displacement by the nitro group, and finally intramolecular cyclization. Reaction of these 3‐nitrosoimidazo[1,2‐a]pyridines with aldehydes in the presence of Fe/AcOH furnished 5‐substituted pyrido[2′,1′:2,3]imidazo[4,5‐c]isoquinolines by reduction of the nitroso group followed by a Pictet–Spengler reaction in one pot. The synthesized compounds were assessed for their antibacterial and antifungal activities.