Selective Intermolecular [2 + 2] Cycloaddition Reaction Using Platinum(II) Catalyst with Hollow-shaped Triethynylphosphine

Intermolecular [2 + 2] cycloaddition reaction of an allenyl silyl ether with vinyl ethers was realized on the basis of electrophilic activation of the allene by the platinum–phosphine catalyst, affording the corresponding methylenecyclobutanes in good yield. The use of the bulky trialkynylphosphine as a ligand was indispensable to achieve highly selective [2 + 2] cycloaddition.