Studies on the Generation of Metalating Species Equivalent to the Knochel-Hauser Base in the Dehydrobrominative Polymerization of Thiophene Derivatives

Dehydrobrominative polycondensation of 2-bromo-3-hexylthiophene proceeded with TMPMgBr center dot LiBr and (TMP)(2)Mg center dot 2LiBr, formed by LiTMP and MgBr2, which was found to serve as a surrogate of the Knochel-Hauser base TMPMgCl center dot LiCl, and head-to-tail-type regioregular poly(3-hexylthiophene) was obtained with high efficiency. The regioregular poly(3-hexylthiophene) was also found to be obtained by one-shot addition of 2-bromo-3-hexylthiophene as a monomer, magnesium amide, and a nickel catalyst, suggesting that complete formation of metalated thiophene species is not an essential requisite for the successful polymerization with a nickel catalyst. This method was employed for the preparation of tolyl-terminated polythiophene by an aryl group with narrow molecular weight distribution using (o-tolyl)NiCldppp as a catalyst.