Palladium-catalyzed syntheses of polyethynyl-substituted 2,2′-bithiophenes

Article abstract of DOI:10.1002/hlca.19960790318

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)₂NH yields substituted polyethynyl-2,2′-bithiophene compounds. The Me₃Si 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.