Thermal [2+ 2] cycloaddition of allenes with an additional multiple bond is described. By simply heating the allenenes or allenynes having a three-atom tether in an appropriate solvent such as dioxane or DMF, the distal double bond of the allenic moiety regioselectively participates in the cycloaddition to form bicyclo [4.2. 0] oct-5-ene derivatives in good to excellent yields. In all the reactions of allenenes, the olefin geometry was completely ...
