Lewis Acid/Bronsted Acid Mediated Benz-Annulation of Thiophenes and Electron-Rich Arenes

A facile preparation of benz-annulated heterocycles were achieved at rt involving a Lewis acid/Bronsted acid mediated annulation of heterocycles using 2,5-dimethoxytetrahydrofuran as a four-carbon synthon. The benz-/naphth-annulation was found to be successful with electron-rich arenes as well.