Sulfurane dication

Stereochemical features of 130 favor formation of a sulfurane dication 131 by treatment with concentrated sulfuric acid.132,133 The sulfuranyl dication 133 is postulated to be involved in the 1,5-oxygen migration observed in the reaction of monosulfoxide 132 with trifluoroacetic acid (Scheme 50).82... 

In the course of the studies on transannular interaction [76] between heteroatoms, Furukawa and co-workers have recently reported some interesting new stable azasulfuranes [77], sulfurane dications bearing two sulfur atoms [78], and selenurane dications bearing two sulfur and selenium atoms as ligands which are annelated in two five-membered diazocine skeletons. As shown in Scheme 35, the central sulfur atom of the tris-sulfide 76 can be converted... 

Generation of disulfonium dications involves stabilization of the cationic centers on the sulfur atoms through formation of a new S-S bond between the two sulfonium centers. When such an interaction involves more than two chalogen atoms, it leads to formation of new interesting types of dications, which contain hypervalent central atoms, such as sulfurane, selenurane or tellururane.94... 

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