Sodium borohydride → 5,6-Dihydro-4,5-dihydroxy-4H-thieno[2,3-b]thiopyran-2-sulfonamide-7,7-dioxide

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Reaction Conditions

Reaction Steps

A solution of 6H-thieno[2,3-b]thiopyran-2-sulfonamide-7,7-dioxide (1.15 g, 0.0043 m) in tetrahydrofuran (20 ml) was added to a stirred solution of barium chlorate monohydrate (2.23 g, 0.0069 m) in water (20 ml) under a nitrogen atmosphere. Osmium tetroxide (0.66 g, 0.0026 m) was added and the mixture was stirred at 45° C. for 22 hours. Sodium borohydride (0.16 g, 0.0043 m) was added portionwise and the mixture was stirred at ambient temperature for one hour. After filtering through "Super-Cel", the filtrate was concentrated under reduced pressure at 30° C. to remove tetrahydrofuran, the aqueous suspension was acidified with 6N hydrochloric acid (1.0 ml) and extracted with ethyl acetate (3×75 ml). The combined extracts were washed twice with water, dried over sodium sulfate and concentrated in vacuo to yield 0.81 g (63% yield) of crude product which was purified by chromatography on silica gel, eluting with 15% methanol-chloroform. Recrystallization from nitromethane afforded an analytical sample melting at 182.5°-185° C.

Provenance & Evidence