HOAc-Mediated Cyclocondensation of 2-Formylazaarenes and Cyclic Amines. Synthesis of Pyrrolo[1,2- a]azaarenes.

In this paper, a concise, easy-operational, high-yield, one-pot method for the synthesis of pyrrolo[1,2- a]azaarenes is described by a straightforward HOAc-mediated double condensation of substituted 2-formylazaarenes (2 equiv) and cyclic amines (1 equiv) in refluxing toluene. Only water is generated as a byproduct. A plausible mechanism is proposed and discussed. This protocol provides a highly effective annulation via two carbon-nitrogen (C-N) and one carbon-carbon (C-C) bond formations.