Chlorine → HCID 19003523, compound

Participants

Reaction Steps

The process comprises displacing the C(2)-chloro of 3-acetyl-2,5-dichlorothiophene (1) with benzyl mercaptide to form the thioether of structure (2), which is then converted to 3-acetyl-5-chloro-2-thiophenesulfonamide (3) by reaction with chlorine to form 3-acetyl-5-chloro-2-thiophenesulfenyl chloride, followed by reaction with ammonia to form 3-acetyl-5-chloro-2-thiophenesulfenamide, and finally oxidation. Bromination provides 3-bromoacetyl-5-chloro-2-thiophenesulfonamide (4), which is converted to (S)-3,4-dihydro-6-chloro-4-hydroxy-2H-thieno[3,2-e]-1,2-thiazine-1,1-dioxide (5) by reduction with (+)-β-chlorodiisopinocampheylborane followed by treatment with aqueous base. Alkylation at N(2) provides the (S)-3,4-dihydro-6-chloro-4-hydroxy-2-substituted-2H-thieno[3,2-e]-1,2-thiazine-1,1-dioxide of structure (6). Formation of the C(6) anion is accomplished by halogen-metal exchange, and the anion is reacted with sulfur dioxide to form a lithium sulfinate, which upon reaction with hydroxylamine-O-sulfonic acid provides the (S)-3,4-dihydro-4-hydroxy-2-substituted-2H-thieno[3,2-e] -1,2-thiazine-6-sulfonamide-1,1-dioxide of structure (7). Protection of the C(6)-sulfonamide functionality, followed by activation of the C(4)-hydroxyl and displacement with an appropriate amine provides the (R)-3,4-dihydro-4-alkylamino-2-substituted-2H-thieno[3,2-e]-1,2-thiazine-6-sulfonamide-1,1-dioxide of structure I.

Provenance & Evidence