Alkoxide-Promoted Rearrangements of 1,3-Dithianes

Article abstract of DOI:10.1021/jo01300a040

The allylic alcohols formed from 1,2-addition of 2-lithio-1,3-dithianes to α,β-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 illustrated in a synthesis of DL-muscone, a 15-membered-ring ketone, from cyclotridecanone.Attempts to induce a similar rearrangement by replacing the 1,3-dithiane group with a thiophenyl or 1,3-dithiolane group proved unsuccessful.