Lewis acid catalyzed rearrangement of vinylcyclopropenes for the construction of naphthalene and indene skeletons

The choice of Lewis acid catalyst can result in dramatic differences in the chemoselectivity of the rearrangement reactions of vinylcyclopropenes. When BF3 center dot OEt2 was used as the catalyst, naphthalenes were formed. However, when Cu(OTf)(2) was used as the catalyst, indenes were obtained.