Preparation and radical ring‐opening polymerization of exo‐methylene substituted cyclic ketene acetals

Preparation and radical ring‐opening polymerization of the exo‐methylene substituted cyclic ketene acetals, 2,4‐dimethylene‐1,3‐dioxolane (I) and 2,5‐dimethylene‐1,3‐dioxane (II), were carried out. Ketene acetals I and II were prepared by dehydrohalogenation of the corresponding cyclic haloacetal with potassium tert‐butoxide in tetrahydrofuran at –78°C and ambient temperature, respectively. I underwent radical polymerization with essentially quantitative ring‐opening with di‐tert‐butyl peroxide in dimethylformamide at 120°C. On the other hand, II underwent both ring‐opening polymerization and vinyl polymerization under the same conditions of the polymerization of I. The differences of polymerization behavior between I and II were also discussed.