| Summary: | Five tri- and tetra-substituted electron-poor olefins containing a β-leaving group, initiated cationic polymerization of p-methoxystyrene with widely varying results. As the electrophilicity of the electron-poor olefins increased, the yields and molecular weights of the polymers formed decreased. The same was true when the excellent leaving group, trifluoromethanesulfonate, was replaced by the poorer leaving group, chloride. Another series of tri-substituted olefins was prepared and reacted with p-methoxystyrene in the presence of excess methyl methacrylate or styrene. Terpolymer was formed as a major product when the electron-poor olefin used contained an α-ester group. The yield of the terpolymer increased with the increasing electrophilicity of the electron-poor olefin. The reactions of methyl α-cyanoacrylate with a number of electron-rich olefins were also studied and found to give new types of adducts, such as Diels-Alder adducts and pyrans. All these reactions were suggested to go through the formation of a tetramethylene intermediate, a resonance hybrid of a zwitterion and spin paired biradical.
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