Pd-Catalyzed one-pot sequential cross-coupling reactions of tetrabromothiophene.

Unsymmetrical one-pot sequential cross-coupling reactions of sterically hindered tetrabromothiophene with arylboronic acid and an alkyne/alkene to afford selective bi-, tri-, and tetrasubstituted aryl/alkynyl-thiophenes with the aid of a palladium catalyst were described. The reaction proceeds via a site-selective Suzuki/Sonogashira coupling, followed by selective Sonogashira, Suzuki and Heck coupling reactions. This methodology has demonstrated an important framework for the synthesis of organic scaffolds.