Regioselective Michael-induced cyclisation of γ- and δ-hydroxy vinyl sulfides and vinyl dithiocarbamates

We herein describe the unprecedented use of heteroaryl vinyl sulfides and vinyl dithiocarbamates as hetero-Michael addition acceptors. Combined chelating and electron-withdrawing effects are postulated to stabilise the transient anionic species and allow smooth Michael-induced ring closure to produce diversely functionalised C-glycosides.