Abstract Tributyltin derivatives of 2-bromo-3-octylthiophene and 5-bromo-4-octyl-2, 2′-bi (thiophene) have been selectively prepared. Condensation reactions in the presence of Pd 2 (dba) 3 (CHCl 3)/4 PPh 3 led to high yields (ca. 90%) of regioregular poly (3- octylthiophene)(M w= 21.4× 10 4, M w/M n= 1.48) and poly [4-octylbi (thiophene)](M w= 3.8× 10 4, M w/M n= 1.1). The regioregularity of the head-to-tail (HT) coupling has been ...