Abstract Fluorosulfuric acid, a very poor nucleophile, was found to add to several epoxides, yielding 1, 3, 2-dioxathiolane 2, 2-dioxides. These cyclic sulfates could also be obtained by reacting the epoxides with sulfur trioxide. The intermediacy of the fluorosulfate of a 1, 2-diol, which readily cyclized in base, has been demonstrated in one case.
