Sterics versus Electronics: Regioselective Cross‐Coupling of Polybrominated Thiophenes

Abstract

AbstractMethods for the regioselective cross‐coupling of 2,3,5‐tribromothiophene have been developed in which selective aryl–aryl coupling occurs at the 5‐position with yields up to 63 %. The difference in reactivity of the α‐ and β‐positions then allows sequential regioselective couplings first at the 2‐position, followed by the 3‐position. Such regioselective cross‐coupling allows unprecedented control in the generation of trifunctionalized thiophenes. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)