Condensation of phenols and alcohols with 1,2-dichloroethyl-gem-dichlorocyclopropanes

Dichlorocarbenation of 3,4-dichlorobut-1-ene by Makosza method results in the stereoisomeric 1,2-dichloroethyl-gem-dichlorocyclopropanes in a 1:1 ratio. The reaction of the mixture of stereoisomeric gem-dichlorocyclopropanes with phenols and alcohols in dimethylsulfoxide in the presence of solid sodium hydroxide gives rise to the corresponding ketals containing the exocyclic double and triple bonds. In this case, the acetylene compounds dominate in the reaction products. The ratio of the reaction products containing the double and triple bonds depends on the nucleophile nature.