Palladium‐Catalyzed Syntheses of Polyethynyl‐Substituted 2,2′‐Bithiophenes

Abstract The syntheses of polyethynyl‐substituted 2,2′‐bithiophenes 2 and related 5,5′‐dicarbaldehyde derivatives 1 are described. The treatment of easily available polybrominated 2,2′‐bithiophenes 3 and 2,2′‐bithiophene‐5,5′‐dicarbaldehydes 4 with phenyl or (trimethylsilyl)acetylene in the presence of Pd II and Cu I in (i‐Pr) 2 NH yields substituted polyethynyl‐2,2′‐bithiophene compounds. The Me 3 Si protecting groups can be removed by protodesilylation under basic conditions to give the corresponding terminal ethynyl groups. These polyethynyl‐bithiophenes could be interesting precursors for the synthesis of macrocycles with interesting properties.