Intramolecular electrophilic aromatic substitution reactions with methyl vinyl ethers for the synthesis of dihydronaphthalenes

A simple and inexpensive method to effect the conversion of 4-arylalk-1-en-1-yl methyl ethers to dihydronaphthalenes has been developed. Cyclisation is accomplished by warming a toluene solution of the substrate with 1,2-ethanediol and para-toluenesulfonic acid and proceeds via in situ formation of a 1,3-dioxolane. Reactions generally give good yields and have been successful with electron rich, unsubstituted and halogenated arenes. They display excellent regioselectivity; appearing to follow the course of lowest steric demand.