After metalation of 3-phenylsydnone by using n-BuLi or n-BuMgBr, 4-(2-hydroxyisopropyl)-3-phenylsydnone and 4-(1-hydroxy-1-ethyl)-3-phenylsydnone are obtained by addition reaction of acetone and acetaldehyde, respectively. The subsequent dehydration of each cabinol using P2O5 produces the corresponding alkenylsydnones. Polymerization reaction is carried out using this 4-vinyl-3-phenylsydnone; the reaction does not occur in the presence of radical initiator, on the other hand, the dimer is formed under cationic initiator, BF3-etherate and its structure is proposed. But the oligomer is obtained under the anionic polymerization condition.