Synthesis of hindered and functionalized 1-CF3 substituted olefins via a carbolithiation-elimination-metalation cascade

Addition of organolithium reagents to trifluoromethyl enol ethers 1a-d and thio enol ethers 2a provided stereoselectively the corresponding trisubstituted fluoroalkenes 3a-d in 70-90% yields. The products could themselves react with organolithium reagents and undergo a vinyl metalation providing, after trapping with an electrophile, tetrasubstituted olefins in excellent yields and with stereoselectivity. This method can be applied to other fluoroalkyl enol ethers (Rf = C2F5). The product, tetrasubstituted olefin, can be obtained directly from enol ether with 2 equiv of reagent through a carbolithiation-elimination-metalation cascade.