A direct route to polythiophenes displaying lateral substituents: Easy one-step synthesis and polymerization of thiophene monomers substituted by a dimethylenecarboxylate (CH2CH2COOR) appendage on the 3-position

Thiophene monomers displaying a dimethylenecarboxylate (CH2CH2COOR) substituent on the 3‐position of the aromatic ring can be easily obtained and in one step from the electrochemically induced reaction of 3‐bromothiophene with the corresponding acrylate (CH2CHCOOR). The synthesis of the ethyl ester monomer, of related 2,5‐dihalogenothiophenes, and their polymerization are reported. Despite the surprisingly low solubilities displayed by the polymers, a full spectroscopic characterization could be performed and the data fully analyzed. Oxidative polymerizations (FeCl3 or electropolymerization) yield a regioirregular polythiophene, with 60–70% of head‐to‐tail diads. Both experimental and theoretical results suggest that the nonconjugated ester plays a very minor role—if any—in the polymerizations under oxidative conditions, but has a significant influence on the polymer properties. Preliminary attempts to polymerize the dihalogenothiophenes under reductive conditions were hampered by the even lower solubilities exhibited by the regioregular oligomers. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012 Easy access to laterally substituted polythiophenes, a class of functional polymers with vast technological potential, is hampered by the difficulty to obtain polymerizable functional monomers in a simple, economically viable, and versatile way. This contribution describes the direct, one‐step synthesis of thiophenes bearing dimethylenecraboxylate pendent groups on the 3‐position of the heterocycle and the subsequent polymerization of these monomers, using the corresponding ethyl ester monomer as a model.