✍ Scribed by Uwe Dahlmann; Richard Neidlein
No coin nor oath required. For personal study only.
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.
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## Abstract A new synthetic route to 4‐substituted‐2,2′‐bithiophenes has been developed utilizing 4‐bromo‐2,2′‐bithiophene (1). Formation of the bithienyllithium adduct __via__ halogen‐metal exchange was found to be problematic and resulted in complex mixtures of products. The Grignard reagent of 1