Sulfur Dioxide → 3,4-Dihydro-2-(3-methoxypropyl)-3-methyl-2H-thieno[3,2-e]-1,2-thiazine-6-sulfonamide 1,1-dioxide

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Reaction Conditions

Reaction Steps

To a solution of the product from Step C (890 mg, 3.23 mmol) in THF (8 mL) at -78° C. was added n-butyllithium (2.0 mL of a 2.5M solution, 4.85 mmol). This mixture was stirred at -78° C. for 40 min and sulfur dioxide was added until the solution maintained a pH of 3. The reaction mixture was warmed to room temperature, stirred for 30 min, and evaporated to a residue which was dissolved in water (20 mL). Sodium acetate (795 mg, 9.69 mmol) and hydroxylamine-O-sulfonic acid (1.0 g, 9.69 mmol) were added, the mixture stirred at room temperature for 18 hr, and the pH was adjusted to 8 with sodium bicarbonate. This solution was extracted with ethyl acetate (2×100 mL), the extracts were dried (MgSO4) and evaporated to a residue which was purified by column chromatography (silica, 5:1 methanol/methylene chloride) to give the desired product. Recrystallization from methylene chloride gave a white solid (320 mg, 29%): mp 140° C. Analysis: Calculated for C11H18N2O5S3 : C, 37.27; H, 5.12; N,7.90. Found: C, 37.38; H, 5.18; N, 7.86.

Provenance & Evidence