In the presence of a catalytic amount of trityl perchlorate or diphenylboryl triflate, acetals react smoothly with allyltrimethylsilanes to give the corresponding homoallyl ethers in good yields with good regio- and stereoselectivities.
Access to 1,3-disubstituted cyclohexenes from zirconocenes containing a latent electrophilic allylic fragment is described. Requiring a specific conformation, 6-endo-trig cyclisation is based on the TMSOTf-mediated generation of a stabilized carbocation.