Low-valent titanium and zirconium reagents in situ prepared from metallocene dichlorides (Cp 2 MCl 2 : M = Ti, Zr) and magnesium powder activated by 1,2-dibromoethane smoothly reacted with allyl propargyl ethers to afford 3-methylenetetrahydrofurans in good yields. It is noteworthy that the Cp 2 Zr- and Cp 2 Ti-mediated cyclizations proceed with inverse stereoselectivity.