The reaction of β-iodo-α, β-unsaturated γ-sultones (ie, 4-halo-1, 2-oxathiole 2, 2-dioxides) in aprotic polar solvents such as DMSO or acetone, with'soft'nucleophiles such as iodide or thioacetate, yields an allenesulfonate by a very facile halophilic ring-opening E2-elimination. The'harder'nucleophile, azide ion, reacts under the same conditions to yield the corresponding β-azido-α, β-unsaturated γ-sultone (ie, 4-azido-1, 2-oxathiole 2, 2-dioxide), ...
