S-oxides. These in turn were suitable precursors of corresponding α,α′-dioxosulfine dienes with tethered internal electron-rich doublebonds. Examining the synthetic utility of these sulfines, we observed either hydrolysis or intramolecular cycloaddition, depending on the distance between the reactive centres and the substitution on the double bond. Bicyclic derivatives with a [3.3.1] skeleton and an sp2