A highly selective cascade approach to diverse aromatic ring systems from simple aromatic aldehydes and propiolates

A new triethylamine-catalyzed cascade reaction of aromatic aldehydes with propiolates has been developed. This serial multi-bond-forming process furnishes diverse polycyclic aromatic hydrocarbons, including naphthalenes, phenanthrenes, benzofurans, and 2,3,9,9a-tetrahydronaphtha-[2,3-b]furans. The chemical outcome of the process depends on the reaction temperature and can be tailored selectively by an appropriate choice of experimental conditions.