Transition-Metal-Free Homopolymerization of Pyrrolo[2,3-d:5,4-d']bisthiazoles via Nucleophilic Aromatic Substitution

Novel methods to synthesize electron-deficient π-conjugated polymers utilizing transition-metal-free coupling reactions for the use of nonfunctionalized monomers are attractive due to their improved atom economy and environmental prospective. Herein we describe the use of ⁱPrMgCl·LiCl complex to afford thiazole-based conjugated polymers in the absence of any transition metal catalyst, that enables access to well-defined polymers with good molecular weights. The mechanistically distinct polymerizations proceeded via nucleophilic aromatic substitution (S_NAr) reaction supported by density functional theory (DFT) calculations. This work demonstrates the first example of fully conjugated thiazole-based aromatic homopolymers without the need of any transition metal catalyst.