Organic Chemistry Seminar
Olefin metathesis provides a versatile synthetic method to produce small, medium and large molecules. Ru-based Grubbs catalysts have popularized the reaction because the catalysts are not only highly active but also very easy to handle with good functional group tolerance. Now the metathesis polymerization of olefin monomers is one of the most common ways to construct numerous polymer architectures and nanostructures. On the other hand, only a few studies reported the polymerization of alkyne-containing molecules, which can efficiently produce conjugated backbone. In fact, in the history of cyclopolymerization of diynes, Grubbs catalysts had shown poor activity and resulted in no polymer, whereas Mo-alkylidenes had achieved the efficient cyclopolymerization. Here, we will describe cyclopolymerization using Grubbs catalysts. Especially, based on extensive mechanistic investigations, our strategy to achieve controlled cyclopolymerization to prepare polymers with desired molecular weights and narrow polydispersity indices will be discussed. Finally, application to synthesize various complex macromolecules such block copolymers, dendronized and graft polymers will be presented.