Tetramethylene sulfoxide → 4-(2,2,2-Trifluoroethoxy)-1-naphthyl-tetrahydrothiophenium 2-(adamantane-1-carbonyloxy)-1,1,3,3,3-pentafluoropropane-1-sulfonate

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Reaction Steps

In 6 g of Eaton's reagent (Aldrich, diphosphorus pentoxide/methanesulfonic acid solution) was dispersed 3 g (0.0127 mol) of 1-(2,2,2-trifluoroethoxy)naphthalene in Synthesis Example 1-3. With stirring, 2.6 g (0.0253 mol) of tetramethylene sulfoxide was added dropwise to the dispersion. The solution was matured overnight at room temperature and combined with 30 g of water and 30 g of diisopropyl ether, from which a water layer was separated. The water layer was again washed with 30 g of diisopropyl ether. This aqueous solution was combined with 5.5 g (0.0101 mol) of benzyltrimethylammonium 2-(adamantane-1-carbonyloxy)-1,1,3,3,3-pentafluoropropane-1-sulfonate in Synthesis Example 1-2, after which extraction was effected twice with 50 g of dichloromethane. The organic layer was washed with water, and the solvent was distilled off in vacuum. The residue was purified by silica gel column chromatography (elute, dichloromethane/methanol). It was dissolved in methyl isobutyl ketone and washed with water, followed by solvent removal and vacuum drying. The product was poured into isopropyl ether for crystallization, filtered and dried, obtaining the target compound. White crystal, 5.6 g, yield 78%.

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