Copper(II)-mediated intramolecular cyclization of (Z)-chalcogenoenynes: Synthesis of 3-halochalcogenophene derivatives

摘要

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.