Cationic ring‐opening polymerization of 2‐isopropenyl‐4‐methylene‐1,3‐dioxolane in donative solvents

2‐Isopropenyl‐4‐methylene‐1,3‐dioxolane ( 1 ) undergoes cationic polymerization in donative solvents without crosslinking to afford poly(ether‐ketone) 2 having two unitstructures. When solvents having medium donor number (DN = 14,1–17,1), such as acetonitrile, dioxane, ethyl acetate, and propylene carbonate, were used, 2 was obtained in high yields. When solvents having DN (>19,2), such as diethyl ether, DMF, and DMAc, were used, the rate of polymerization decreased considerably, although polymerization proceeded even in the most donative solvent, DMAc (DN = 27,8). The ratio of the unit‐structures was independent of the solvent used. When ethanol was used as the solvent, ethoxyacetone and methacrolein were obtained instead of 2 . It was concluded that hard nucleophiles such as ethanol attack at the α′‐position of terminal oxyallyl cation, while soft nucleophiles such as monomer 1 attack at the α‐or γ‐position.