A Step-Efficient Pathway to Chlorine-Functionalized Thiophene Oligomers by Palladium-Catalyzed Deprotonative Coupling of Chlorothiophenes

Deprotonative metalation of 2-chloro-3-substituted thiophene at the 5-position of the thiophene ring is performed by using a bulky magnesium amide 2,2,6,6-tetramethylpiperidin-1-yl magnesium chloride lithium chloride salt (TMPMgCl·LiCl). The obtained metallic species reacts with bromothiophene to afford the regioregular head-to-tail-type chlorobithiophene, which is subjected to further end functionalization by the coupling reaction with the C–Cl bond. Deprotonative C–H coupling polycondensation of substituted chlorobithiophene derivatives gives polythiophene as a formal alternating copolymer.