GaCl3-mediated acyclic dimerization of donor–acceptor cyclopropanes using 1,2-dipole reactivity

A new type of dimerization of 2-arylcyclopropane-1,1-dicarboxylates in the presence of anhydrous GaCl₃ to give acyclic dimers, viz., substituted pent-2-ene-1,1,5,5-tetracarboxylates, occurs at room temperature. In this reaction, one molecule of the donor–acceptor cyclopropane manifests a non-classical reactivity and serves as a 1,2-dipole.