Switching of the reaction pathway for [1,2]/[1,4]- and [2,3]-Wittig rearrangements of 3-aryl-2-propenyl propargyl ethers
Abstract
3-Aryl-2-propenyl propargyl ethers (1) undergo the [1,2](and [1,4]) sigmatropic rearrangement periselectively on treatment with BunLi at –78 °C, whereas the silylated derivatives (2) perform exclusively the [2,3]-Wittig rearrangement.