Sulfuric Acid → 6H-Thieno[2,3-b]thiopyran-2-sulfonamide-7,7-dioxide

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Reaction Conditions

Reaction Steps

A mixture of 5,6-dihydro-4-hydroxy-4H-thieno[2,3-b]thiopyran-2-sulfonamide-7,7-dioxide (0.90 g, 0.0031 m), concentrated sulfuric acid (3 ml), and trifluoroacetic acid (20 ml) was stirred and heated at 50° C. for 20.5 hours. After removal of trifluoroacetic acid under reduced pressure, the residue was dissolved in ethyl acetate (25 ml) and the solution was washed with water, twice with saturated sodium bicarbonate solution, twice more with water and dried over sodium sulfate. The solvent was concentrated in vacuo to yield 0.74 g (90%) of crude product. The product was purified by recrystallization from nitromethane after treatment with decolorizing carbon. An analytical sample melted at 214.5°-216° C. (See Example 26).

Provenance & Evidence