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Rearrangement of β-hydroxy sulfides proceeds stereospecifically with capture of the episulfonium ion by the nitrogen atom of an amide. Almost quantitative yields of substituted pyrrolidines are obtained using a sulfonamide as the intramolecular nucleophile and with activation by trimethylsilyl trifluoromethanesulfonate (TMSOTf). With a free amine no cyclization takes place, but instead allylic sulfides are formed.
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Coldham et al. (1993) studied this question.
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