A hyperbranched polythiophene with the degree of branching of almost 100% has been successfully prepared by the catalyst-transfer Suzuki–Miyaura coupling reaction of an AB2 monomer containing the phenyl boronic acid pinacol ester and dibromothiophene units as the A and B2 functionalities, respectively. The model reaction of 2,5-dibromothiophene with an equivalent of 3-methoxyphenylboronic acid pinacol ester proceeded in a catalyst-transfer manner, predominantly leading to a diarylated product. Based on these findings, a new AB2 monomer was designed and synthesized. The obtained polymer was characterized by 1H and 13C NMR spectroscopies, which showed a nearly defect-free HBP.
