(3 + 3)-Cyclodimerization of Donor–Acceptor Cyclopropanes. Three Routes to Six-Membered Rings

The ability of donor–acceptor cyclopropanes to (3 + 3)-cyclodimerize is disclosed. It has been found that Lewis acid-induced transformations of 2-(hetero)­arylcyclopropane-1,1-dicarboxylates containing electron-abundant aromatic substituents led to the construction of six-membered cyclic systems. Depending on the substrate properties and the Lewis acid applied, three types of products can be obtained: (1) 1,4-diarylcyclohexanes, (2) 1-aryl-1,2,3,4-tetrahydronaphthalenes, and (3) 9,10-dihydroanthracenes.