P, y-Unsaturated ketones are prepared with regiospecific CC bond formation at the former y- position of primary, secondary, or tertiary allylic alcohol precursors by a process involving [3.3] sigmatropic Claisen rearrangement of intermediate a-allyloxy ketone enolates or the corresponding trimethylsilyl enol ethers. Although enolates of a-allyloxy ketones might be intermediates, byproducts from competing [1.2] or [2.3] sigmatropic rearrangements of a- ...
