Copper(II)‐Mediated Intramolecular Cyclization of (<i>Z</i>)‐Chalcogenoenynes: Synthesis of 3‐Halochalcogenophene Derivatives

Abstract

Abstract We present our results on the cyclization of ( Z )‐chalcogenoenynes mediated by copper(II) salts to afford 3‐halochalcogenophenes in satisfactory yields through an intramolecular 5‐ endo‐dig cyclization. The methodology was carried out using CuCl 2 at 50 °C or CuBr 2 at room temperature under an ambient atmosphere. The reaction took place under very mild reaction conditions and tolerated considerable functionality. One 3‐bromo‐selenophene derivative was applied as a substrate in the palladium‐catalyzed cross‐coupling reaction with a boronic acid to give the Suzuki type product in good yield.