Synthesis of brominated substrates
The parent compounds of 1c and 1d were coupled via a Suzuki coupling reaction according to literature and subsequently
brominated with NBS to obtain the spacer-extended thiophenes 1c and 1d:
Scheme 4
Dibromo - acetylenedithienyl (1a) could not be obtained via analogous bromination of the
parent compound, so a different strategy via a direct coupling reaction had to be employed:
Scheme 5