Rapid Synthesis of Polycyclic Aromatic Compounds by Iodocyclization of Ynamides

Ynamides are recognized as electron-rich π-components and show high reactivity toward electrophiles such as iodonium salts. Here we report the iodocyclization of ene-ynamides and arene-ynamides leading to naphthalenes and phenanthrenes. We found these reactions were completed within 3 seconds by using I(coll)₂PF₆ as an iodonium reagent, and cyclized products were obtained in good to high yields. To the best of our knowledge, this method is the most rapid synthesis known to date of polycyclic aromatic compounds.