Synthesis and Properties of Aza-ullazines.

A range of aza-ullazines, which represent a new heterocyclic core structure, were synthesized through a scalable four-step reaction, including a Sonogashira reaction and metal-free cyclization promoted by p-toluenesulfonic acid. The optical and electrochemical properties of selected derivatives were investigated, they were found to have similar absorption and emission spectra but a higher oxidation potential than the parent ullazine core.