The allylic alcohols formed from 1, 2-addition of 2-lithio-1, 3-dithianes to a,@-unsaturated ketones have been shown to undergo [1, 3] rearrangement to afford their respective Michael- addition products upon treatment with KH in HMPA/THF in some cases. The major side reaction and in some instances the sole reaction pathway was fragmentation. The rearrangement was applied to a two-carbon macrocyclic ring-expansion strategy which is ...