A Pt(II)- catalyzed [3 + 2] cycloaddition reaction of sityl propadienyl ethers and alkenyl ethers has been developed as the first example of the utilization of allenes as a three-carbon unit in a transition-metal-catalyzed intermolecular cycloaddition reaction. Pt(II)-containing 1,3-dipole equivalents generated by electrophilic activation of sityl propadienyl ethers using a Pt(II) catalyst reacted with various electron-rich alkenes to give synthetically useful functionalized cyclopentene derivatives in high yield with wide generality.