Nickel-Catalyzed Alkene Difunctionalization as a Method for Polymerization

Alkene dicarbofunctionalization is a rapidly emerging tool for complex molecule synthesis that installs two carbon fragments regioselectively across an alkene. This method has the potential to engineer stereodefined polymers, yet the application of difunctionalization reactions to polymer synthesis remains unexplored. Herein, we describe the first example of a Ni-catalyzed difunctionalization of alkenes with arylboronic esters and aryl bromides innate to the alkene. The polymerization reaction proceeds regioselectively with the addition of the aryl bromide to the terminal alkenyl carbon and arylboronic ester to the internal benzylic carbon. The resultant poly[arylene-α-(aryl)ethylene]s comprise aryl groups installed at regular intervals along the polymer backbone through chain propagation in two directions. Polymers with molecular weights generally ranging from 30 to 175 kDa were obtained after successful fractionation from oligomeric species. Thermal analysis of the poly[arylene α-(aryl)ethylene]s revealed stability up to ∼399 °C, with a T_g of 90 °C, both of which are similar in value to poly(styrene)s and poly(phenylene methylene)s.