High Electron Mobilities with Oligothiophenes Bearing Hexafluorocyclopentene

Significance

The authors synthesized the hexafluorocyclopentene bearing oligothiophene derivatives 5, 6, and 7 containing 2, 4, and 6 thiophene units, respectively. The important fluorination of the starting material 1 was carried out using a procedure previously reported by Aso and co-workers (Org. Lett. 2006, 8, 5381). The subsequent steps involve partial TIPS-protection and oxidative coupling with CuBr₂ and Fe(acac)₃, respectively. Conventional cross-coupling reactions such as Stille, Negishi, and Suzuki failed for the reported transformations. The products 5-7 exhibit increasing red shifts in their absorption spectra with increasing chain length, suggesting that the fluorination has little effect on the conjugation.