A New One-Pot Synthetic Method for Selenium-Containing Medium-Sized α,β-Unsaturated Cyclic Ketones

The reaction of tetrahydroselenopyran-2-one (7) with ethynyllithiums 20a-h, followed by treatment with aqueous 5% H2SO4 successfully led to a two-carbon ring expansion to give the 2-substituted 5,6,7,8-tetrahydroselenocin-4-ones 21a-h in 43-95% yields. Seven- to nine-membered γ-selena-α,β-unsaturated cyclic ketones 22-26 and a 5,6,7,8-tetrahydrotellurocin-4-one 27 were also prepared from the corresponding selenolactones or tellurolactone in a one-pot reaction.