Hydrochloric Acid → HCID 20375541, compound

Participants

Reaction Steps

1.8 g (8.3 mmol) of 3,4-dihydro-2-methyl-3-oxo-2H-thieno[3,2-e]-1,2-thiazine 1,1-dioxide are stirred for 24 hours at room temperature under nitrogen with 1.6 g (8.3 mmol) of p-bromophenylisocyanate and 0.84 g (8.3 mmol) of triethylamine in 20 ml of absolute dimethyl sulfoxide. Thereafter, the mixture is poured into 50 ml of 2-N hydrochloric acid and 20 g of ice. The separated precipitate is filtered off under suction and washed neutral with water. The filter residue is taken up in 200 ml of methylene chloride, dried over sodium sulfate, stirred with 1 g of active carbon and filtered. The filtrate is extracted with four 100 ml portions of semi-saturated sodium carbonate solution, each of the organic phases being re-extracted with a small amount of methylene chloride. The combined aqueous phases are acidified to pH 1 with concentrated hydrochloric acid. The separated product is extracted with three 100 ml portions of methylene chloride. The combined organic phases are dried over sodium sulfate and evaporated, whereby the product crystallizes out. For purification, the product is recrystallized from ca 30 ml of methanol to give 3-hydroxy-2-methyl-4-(4-bromophenylcarbamoyl)-2H-thieno[3,2-e]-1,2-thiazine 1,1-dioxide of melting point 197°-199° C.

Provenance & Evidence